OFP is a class of plant-specific transcription factors that play important roles in the regulation of plant organ morphogenesis and response to abiotic stresses.In order to study the characterization of soybean OFP transcription factor family members and their roles in drought stress and salt stress,bioinformatics methods were applied to identify and analyze soybean OFP family members.The results showed that:a total of 41 GmOFPs,named GmOFP-1—GmOFP-41,were identified in soybean;these genes were unevenly distributed on 19 chromosomes of soybean,encoding 152—414 amino acids;subcellular localization predicted that soybean OFP proteins were mainly localized in nucleus,chloroplasts,and mitochondria;a total of 10 conserved motifs were identified in soybean OFP proteins,conservative Motifs 1 and 2 were present in all OFP members.Phylogenetic analysis classified soybean and Arabidopsis OFP proteins into five subfamilies ClassⅠ—Class V,of which soybean OFP family genes were mainly distributed in ClassⅠ and Class Ⅲ.The collinearity analysis revealed that 75 pairs of genes in the soybean genome had collinearity,four pairs of genes had tandem duplications,and only two genes,GmOFP-2 and GmOFP-39,did not have collinearity,which indicated that gene fragment duplication was the main reason for the increase in the number of soybean OFP family members.The expression patterns of GmOFP gene family members under drought stress and salt stress treatments were analyzed by qRT-PCR,and the results showed that,compared with the control,16 members out of 41 GmOFP genes exhibited significant differences in gene expression levels after drought treatments,with significant up-regulation of the expression of GmOFP-15,GmOFP-17,and GmOFP-32,while the GmOFP-4,GmOFP-5,GmOFP-6,GmOFP-9,GmOFP-12,GmOFP-21,GmOFP-23,GmOFP-25,GmOFP-26,GmOFP-27,GmOFP-38,GmOFP-39,and GmOFP-40 were significantly down-regulated after drought treatment.Eight members of GmOFPs showed significant differences in gene expression levels after salt treatment,among which GmOFP-7,GmOFP-14,GmOFP-31,GmOFP-32,GmOFP-36,and GmOFP-40 were significantly up-regulated,and GmOFP-1 and GmOFP-15 were significantly down-regulated.The above results suggest that the soybean OFP gene family may have important functions in response to drought stress and salt stress.

This study aimed to clarify the regulatory mechanism of exogenous glycine betaine(GB)on the antioxidant and photosynthetic systems of maize seedling leaves under combined heat and drought stress(TD),providing a theoretical basis for alleviating crop stress under extreme environments.Using the maize variety Xianyu 335 as experimental material,different concentrations of GB(0,50,100,200,and 400 mmol/L)were applied to the leaves at the three-leaf-one-heart stage.After 24 hours,combined stress was simulated in a climate chamber with high temperature(day/night temperature of 40 ℃/28 ℃)and 20% PEG-6000 to induce moderate drought,exploring the regulatory effects of GB on the antioxidant system and photosynthesis of maize seedlings.The results showed that 100 mmol/L GB significantly promoted plant growth.Compared with the TD treatment,plant height,leaf area,shoot dry weight,and root dry weight increased by 27.48%,27.45%,28.33%,and 78.26%,respectively,while the root-to-shoot ratio increased by 14.91 percentage points.On the 5th day after stress,100 mmol/L GB significantly enhanced antioxidant enzyme activities,with superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities increasing by 69.09%,69.02%,and 41.81%,respectively.Simultaneously,the contents of malondialdehyde(MDA),superoxide anion($\mathrm{O}^{\bar{.}}_{2}$),and hydrogen peroxide(H₂O₂)decreased by 21.92%,6.50%,and 25.33%,respectively.Furthermore,soluble sugar(SS)and soluble protein(SP)contents increased by 31.69% and 18.98%.Photosynthetic characterization analysis indicated that GB effectively improved the lamellar system structure of chloroplast grana and stroma thylakoids,thereby significantly increasing the SPAD value under combined stress and alleviating damage to the photosystem Ⅱ(PSⅡ)reaction center.This was manifested by a decrease in minimal fluorescence(F0)and increases in variable fluorescence(Fv)and maximum fluorescence(Fm).Additionally,by mitigating the stomatal and non-stomatal limitations caused by combined stress,GB treatment significantly enhanced photosynthetic performance,increasing the net photosynthetic rate(Pn)by 24.14% on the 5th day after stress.In conclusion,under combined heat and drought stress,exogenous GB can protect the photosynthetic system by enhancing antioxidant enzyme activities and osmotic adjustment capacity,thereby alleviating stress damage and promoting the growth of maize seedlings.

This study investigated the impacts of drought on the agronomic,physiological,and biochemical characteristics of peanuts developed a classification methodology for drought resistance,screened the varieties of peanut with drought resistant.Agronomic traits of 27 peanut germplasms under drought stress were measured 30 days after sowing,and drought resistance was graded by correlation analysis,principal component analysis,cluster analysis,and membership function method.Drought-resistant peanut JNH3,intermediate L231,and drought-sensitive L236 were selected for determination of physiological and biochemical indexes and microstructure observation,and different drought-resistant peanut germplasms were identified.The results showed that after drought treatment,the decrease in main stem height ranged from 2.26% to 34.06%,the length of first branches decreased from 1.11% to 57.20%,the main stem base coarse decreased from 1.54% to 38.36%,and the root-shoot ratio decreased from 65.01% to 92.83% under different environments.According to the comprehensive weighted membership function,peanut materials were grouped into three types:drought-resistant,intermediate,and drought-sensitive.Among them, the above-mentioned traits of the intermediate type and the drought-sensitive type peanuts reached a significant level compared with the control. Under drought stress,ROS in functional leaves of peanut increased,and different expressions of ROS were found by NBT and DAB staining,among which NBT and DAB staining were JNH3,L231,and L236 from light to deep,conforming to the classification of drought resistance type.Compared with the control,the POD activity of JNH3,L231,and L236 increased by 42.71%,26.04% and 20.59% respectively,among different varieties,and CAT activity trend was consistent with the above.The SOD activity of JNH3,L231,and L236 increased by 48.01%,63.49% and 73.15% respectively,among different varieties,and the MDA activity trend was consistent with the above.The proline content of JNH3,L231,and L236 was increased by 1.1,1.07 and 1.03 times,and the soluble sugar content of JNH3,L231,and L236 was increased by 44.06%,31.54%,and 38.62% respectively,among different varieties.Under drought stress,peanut root growth was limited,the total root length and total root area were significantly reduced,the root tip cells were partially necrosis,and the degrees were shallow to deep in JNH3,L231,and L236 respectively.

Drought stress has a serious effect on the growth and development of maize,which leads to a decrease of maize yield.Purple acid phosphatase is a phospholipase protein involved in many physiological and biochemical functions of plants.In order to further study the role of purple acid phosphatase family genes in the process of stress resistance of maize,this paper explored the response mode of ZmPAP26b gene under drought stress,and Real-time fluorescence Quantitavive analysis was used to analyze the relative gene expression in different maize inbreeding lines under simulated drought conditions;ZmPAP26b(GenBank:NC_050104.1)was cloned from maize,and PAP genes in Zea mays,Arabidopsis thaliana,Oryza sativa L.,Triticum aestivum L.,Sorghum bicolor and Brachypodium distachyon were identified and bioinformatic analysis was performed.Meanwhile,prokaryotic overexpression strains were constructed for functional verification.The results showed that the expression of this gene decreased in drought tolerant materials and increased in drought sensitive materials under drought stress.The CDS length of this gene was 1 431 bp,encoding 476 amino acids.A total of 228 PAP genes were found in six species,divided into 4 subfamilies by phylogenetic analysis.The 19 PAP genes in maize were distributed on 9 chromosomes and had similar conserved domains.Analysis of promoter cis-acting elements showed that they contained elements responding to drought and hormones.Prokaryotic expression experiments showed that the growth of strains containing the recombinant plasmid pET28a-ZmPAP26b was inhibited compared with non-loaded strains under 10% PEG-6000 and 15%PEG-6000 simulated drought stress.In summary,it is speculated that ZmPAP26b is negatively regulated under drought stress.

Metacaspase (MC) belongs to arginine/threonine specific protease,studies have shown that it plays a role in programmed cell death.To investigate the distribution of MC family genes in the genome of Brassica napus and whether they respond to drought stress,this study systematically analyzed the physicochemical properties,phylogeny,gene structure,conserved domains,cis-acting elements,and expression patterns of MC family genes under drought(PEG6000)and abscisic acid(ABA)stress in B.napus.A total of 25 BnMC genes were identified.Chromosomal localization showed that the 25 BnMCs were distributed on 13 chromosomes.Subcellular localization prediction showed that 17 members of the BnMC family were localized in the nucleus and seven members were in the cytoplasm.The phylogenetic tree classified BnMC into two major classes (Type Ⅰ and Type Ⅱ) and four branches (Group A,Group B,Group C,and Group D).BnMCs of the same branch had similar gene structure and conserved motif distribution.The core promoter regions of BnMC contained four types of cis-acting elements:light response element,phytohormone response element,plant growth and development response element and stress response element.Among all the cis-acting elements related to abiotic stress responses,the abscisic acid response element (ABRE) was the most abundant,with a total of 79.All members contained this cis-acting element.The transcriptome sequencing revealed that the expressions of BnMC10,BnMC22,BnMC1,BnMC12 and BnMC8 were up-regulated and the expressions of BnMC4 and BnMC5 were down-regulated after drought treatment.The qRT-PCR assay showed BnMC10,BnMC8,BnMC1 and BnMC12 genes were expressed in both roots and leaves and were up-regulated by both PEG6000 and ABA,with BnMC1 showing the most significant up-regulating changes.In summary,the response of B.napus to drought stress involves the regulation of the expression level of MC family genes.

In order to uncover key genes involved in flax's response to drought stress and elucidate the underlying molecular mechanisms,thereby providing theoretical support for breeding drought-resistant varieties.Using roots of the drought-resistant flax cultivar Tianya 13 as experimental material,drought stress was simulated with different concentrations(5%,10%,20%,30%)of polyethylene glycol(PEG).Based on the analysis of physiological indicators such as root length,root thickness,and dry/fresh weight ratio,20% PEG was identified as the optimal stress concentration,under which the above indicators were significantly reduced by 31.63%,30.50%,and 13.39 percentage points,respectively,compared to the control.Subsequently,Illumina transcriptome sequencing was performed on roots subjected to drought stress at different time points(8,16,24 h),identifying 5 428,5 304,and 3 603 differentially expressed genes(DEGs)at each time point,respectively.KEGG enrichment analysis revealed that these DEGs were significantly enriched in key pathways such as carbohydrate metabolism(12 genes),betaine biosynthesis(4 genes),and the antioxidant defense system(36 genes).qRT-PCR validation of selected DEGs confirmed expression trends consistent with the RNA-seq results,verifying data reliability.This study systematically reveals,that flax enhances drought tolerance through the coordinated regulation of osmotic adjustment substance(e.g.,betaine)synthesis,energy metabolism reprogramming(carbohydrate metabolism),and reactive oxygen species scavenging mechanisms.It provides important theoretical foundations and candidate gene resources for molecular design breeding in flax.

The ubiquitination pathway is one of the key signaling pathways in response to drought stress.In order to clarify the biological function of E3 ubiquitin ligase TaSINA101 gene in response to drought stress,the TaSINA61,TaSINA101 and TaSINA105 genes were cloned from JM47,an excellent drought-resistant wheat cultivar,and their sequence characteristics were analyzed by bioinformatics methods,and the expression levels of the three genes in wheat roots and leaves were detected by qRT-PCR under PEG-6000,NaCl,low temperature and ABA treatments.The heterologous expression of TaSINA101 in transgenic rice was used to analyze the biological function of TaSINA101 in response to drought stress.The results showed that the TaSINA61,TaSINA101 and TaSINA105 genes contained one intron and two exons,and the encoded proteins were composed of 282 amino acids.The qRT-PCR expression analysis showed that the expression of these three genes was induced by various abiotic stresses such as drought stress in roots and leaves.Phenotypic analysis of TaSINA101 transgenic rice under drought stress showed that the leaf fresh weight and dry weight, maximum root length, average root diameter and leaf relative water content of transgenic rice lines OE-1, OE-2 and OE-3 were significantly lower than those of wild type,while the relative conductivity of leaves of transgenic rice lines OE-1 and OE-2 was significantly higher than that of wild type.Therefore,TaSINA101 negatively regulates drought stress tolerance in rice.This study provides a basis for in-depth analysis of the biological function of TaSINA101 gene in wheat.

Light-harvesting chlorophyll a/b binding proteins are important in plant photosynthesis and abiotic stress response.To study the characteristics of GhLhcb2A1 and its expression patterns and functions in low temperature and drought response in upland cotton,full-length CDS of GhLhcb2A1 gene was cloned from the leaf cDNA of Jimian 262 by PCR.Bioinformatic analysis was conducted to learn the basic characteristics of the gene.The expression patterns and functions in low temperature and drought response were evaluated by qRT-PCR and virus-induced gene silencing.It was shown that the length of GhLhcb2A1 CDS was 798 bp,encoding 265 amino acids.GhLhcb2A1 was highly expressed in leaves and was significantly up-regulated in leaves and roots under low temperature and drought treatment.Compared with the control,its expression maximized at 3 h under low temperature and drought in leaves with 17.42 and 30.03 folds increase respectively,whereas maximized at 6 h under low temperature and 12 h under drought in roots with 11.65 and 65.04 folds respectively.Subcellular localization assay verified that GhLhcb2A1 was expressed in the chloroplasts of cells.Compared with the control plants,GhLhcb2A1 silenced plants showed a more severe phenotype of water loss and dryness under both low temperatures and drought.The accumulated malondialdehyde content in the leaves of the silenced plants was significantly higher than that of the control,while the proline content and superoxide dismutase activity were significantly lower than those of the controls,suggesting that GhLhcb2A1 silenced plant reduced the resistance to low temperature and drought.The above results implied that this gene played a positive role in regulating low temperature and drought response.

The effects of different degrees of drought stress on antioxidant enzyme activity, malondialdehyde(MDA)content,photosynthetic characteristics,and yield composition of wheat were investigated to provide a theoretical basis and technical support for optimizing water-saving production of wheat.From 2023 to 2025,four soil water gradients of heavy drought(I-hd),moderate drought(I-md),mild drought(I-fd)and suitable water content(I-sm)were set up in the Longkou Experimental Station of Shandong Academy of Agricultural Sciences.The antioxidant enzyme activity,MDA content,photosynthetic characteristics and grain yield composition of wheat under different drought stress were systematically analyzed.The results showed that compared with moderate and heavy drought,mild drought and suitable water were beneficial to optimize spike number,grain number per spike and 1000-grain weight,thus significantly increasing grain yield,and the average grain yield in two years increased by 11.1%—51.0%.The activities of antioxidant enzymes such as superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)were significantly increased at each growth stage under mild drought and suitable water,and the MDA content in leaves was significantly decreased at each growth stage,which played an important role in reducing the degree of cell membrane lipid oxidation and delaying plant senescence.The leaf area index(LAI),chlorophyll relative value(SPAD value)and net photosynthetic rate(Pn)of leaves at booting,flowering and mid-filling stages were maintained at a high level under mild drought and suitable water conditions,which provided a physiological basis for the improvement of photosynthetic rate,while the above indices were significantly reduced during the whole growth period under moderate and severe drought conditions.The results of correlation analysis showed that the activities of antioxidant enzymes(SOD,POD,CAT)were significantly negatively correlated with MDA content,and significantly positively correlated with photosynthetic characteristics(LAI,SPAD,Pn)and yield components(spike number,grain number per spike,1000-grain weight),which provided physiological guarantee for maintaining higher photosynthetic capacity.In summary,both mild drought and suitable water significantly increase the activities of antioxidant enzymes such as SOD,POD,and CAT in leaves at each growth stage,reduce the content of harmful substances such as MDA,and optimize LAI and SPAD values to improve the photosynthetic rate of leaves.The final grain yield increased by 11.1%—51.0%.However,there was no significant difference in grain yield,antioxidant enzyme activity and photosynthetic characteristics between mild drought and suitable water.Therefore,it is concluded that under mild drought conditions,high and stable yield of wheat can be achieved by optimizing photosynthetic characteristics and leaf antioxidant capacity,which provides a reliable practical approach for water-saving crop production.

To investigate the expression characteristics of OsASL1.1 and its role in the drought stress response,the subcellular localization of OsASL1.1 protein and cis-acting elements in the promoter region of OsASL1.1 gene were analyzed.Additionally,Real-time Quantitative PCR(qRT-PCR)was used to examine the expression patterns of OsASL1.1 in response to abscisic acid(ABA),mannitol,and polyethylene glycol 6000(PEG6000).CRISPR/Cas9 gene editing technology was employed to generate Cas9-OsASL1.1 mutants with Kitaake as background,and the mutation types were characterized.The abscisic acid(ABA)sensitivity and drought tolerance of mutants were analyzed.The results indicated that OsASL1.1 protein was primarily localized in plastids.The promoter region of OsASL1.1 contained cis-acting elements responsive to low temperatures and plant hormones(ABA and auxin),including five ABA responsive cis-acting elements(ABREs).OsASL1.1 expression was induced by ABA,mannitol and PEG6000.Two homozygous mutant types,Cas9-6 and Cas9-12,were generated.Cas9-6 harbored a 17 bp insertion that caused premature translation termination,whereas Cas9-12 had a 12 bp deletion that resulted in the loss of four amino acids.Under ABA treatment,root elongation of Cas9-OsASL1.1 mutants and wild type were inhibited;however,the inhibition was less severe in the mutants than that in the wild type.Under 150 mmol/L mannitol treatment,the survival rates of both Cas9-6 and Cas9-12 mutants were significantly lower than that of wild type,with Cas9-6 showing the lowest survival rate.In summary,the Cas9-OsASL1.1 mutants show reduced sensitivity to ABA and decreased drought tolerance,indicating that the loss of OsASL1.1 function diminishes rice sensitivity to ABA and drought tolerance.

To clarify the effects of drought stress and cultivars on the net photosynthetic rate(Pn),the activities of photosynthetic enzymes in flag leaf in the afternoon(FLA)during grain filling stage and grain yield of winter wheat,a pond culture experiment with four water levels and two winter wheat cultivars was conducted under the condition of rainproof pond cultivation in 2019—2021.The four water treatments included severe drought(W1),moderate drought(W2),mild drought(W3),and suitable water supply(W4).The Pn,and the activities of Rubisco,RCA,PEPC,ATPase and PPDK in flag leaf from 14:00 to 16:00 during the early(EGFS)and medium(MGFS)grain filling stage,and the grain yield at maturity of strong drought resistance cultivar Jinmai 47(JM47)and weak drought resistance cultivar Yanzhan 4110(YZ4110)were investigated.Drought stress decreased the FLA Pn and activities of most photosynthetic enzymes,and the grain yield of wheat.The decrease of these indexes increased with drought stress degree,but the effects were different among varieties and years.Compared with W4,the FLA Pn of JM47 under W1,W2 and W3 decreased by 33.6%—40.6%,12.0%—30.5% and 5.0%—13.5%,as well as YZ4110 decreased by 44.0%—52.0%,22.5%—38.1% and 11.5%—20.5%,respectively.Compared with W4,the FLA Rubisco activity decreased during EGFS but increased during MGFS for JM47,while it decreased by 13.3%—25.6%,7.1%—14.0% and 11.2%—11.6% for YZ4110,respectively,under W1,W2 and W3.Compared with W4,the FLA RCA activity significantly decreased under most drought treatments during EGFS,while increased under W2 and W3 for JM47 and decreased under W1 and W2 for YZ4110 during MGFS.Compared with W4,the FLA ATPase activity of JM47decreased under W1 but increased under W3,while that of YZ4110 decreased under W1,W2 and W3 by 19.3%—48.7%,7.2%—24.2% and 0.1%—8.9%,respectively.The FLA PEPC activity under different treatments varied with growing seasons and varieties.Compared with W4,the FLA PPDK activities of JM47 and YZ4110 under W1 were decreased by 12.4%—18.8% and 16.7%—18.2%.Compared with YZ4110,in most conditions,the FLA Pn and photosynthetic enzyme activities of JM47 had no significant difference under suitable water supply(W4),but increased under drought treatments(W1,W2 and W3).The results of correlation analysis showed that yield,FLA Pn were significantly positively correlated to FLA ATPase activity during EGFS and MGFS,as well as FLA PEPC activity during EGFS.Thus,increasing the FLA ATPase and PEPC activities during the grain filling period is conducive to the increase of FLA Pn and grain yield of wheat.

In order to reveal the response characteristics of potato growth,development,and photosynthetic traits to different water gradients during the critical growth period in semi-arid regions,this study conducted simulated experiments involving waterlogging (soil moisture maintained at 85% field capacity)and drought stress (drought initiated when soil moisture reached 65% field capacity)to investigate various growth traits and photosynthetic parameters of potatoes.The results showed that the plant height and biomass accumulation of potatoes under waterlogging were not different from those under normal irrigation.The plant height growth and biomass accumulation of potato under drought stress were significantly decreased.Meanwhile,the photosynthetic characteristics of potato leaves were significantly decreased under drought stress,including a 43% reduction in net photosynthetic rate and a 55% reduction in stomatal conductance.There was no significant difference in photosynthetic characteristics(except for stomatal conductance)between waterlogging treatment and normal irrigation treatment.Drought stress and waterlogging treatment decreased the photosynthetic capacity and light energy utilization of potato leaves to different degrees.Among them,under waterlogging conditions,the growth and development of potato leaves were more easily inhibited when exposed to strong light,and the activity of potato leaves was reduced.The growth and development of potato leaves were more easily inhibited when exposed to weak light under drought conditions,but the activity of potato leaves was not reduced.Comprehensive analysis showed that potato was more susceptible to drought stress in tuber expansion stage in semi-arid region,followed by longer waterlogging duration affecting potato growth and development.

Auxin response factor(ARF)is a class of transcription factors with B3 domain,which is a direct molecule regulating auxin response and controlling gene expression.A gene,ZmARF10,which encoded ARF protein and actively participated in drought-rehydration stress response,was previously screened in maize by analyzed transcriptome data.To further research the molecular mechanism of ZmARF10 regulating drought resistance of maize,and also provide a new idea for molecular breeding of drought resistance,the gene was firstly analyzed by bioinformatics software.Secondly,Quantitative Real-time polymerase chain reaction(qRT-PCR)was used to detect the expression pattern of ZmARF10 in different tissues,under high temperature,drought,high salt,ABA and restoring treatments,and in different inbred lines.Finally,the function of ZmARF10 was analyzed using CRISPR/Cas9 technology.The results showed that ZmARF10 was located on chromosome 3 of maize,with a total length of 2 127 bp,and encoded 708 amino acids with a typical B3 domain.The upstream 2 kb region of ATG of this gene contained response elements related to methyl jasmonate,auxin,abscisic acid and low temperature.The phylogenetic tree showed that the protein encoded by the ZmARF10 gene was closely related to sorghum.qRT-PCR results showed that ZmARF10 was a constitutive expression gene,and the expression level of ZmARF10 was the highest in mature corn roots of maize.Under high temperature,drought,high salt and ABA treatments,the expression of this gene was significantly up-regulated,and the up-regulation ratio was up to 8.2 times after drought stress.After drought stress,the expression level of ZmARF10 gene was significantly higher in the drought-resistant inbred line Zheng 36 than that in the drought-sensitive inbred line B73.Investigation of Arabidopsis wild type and ARF10-deficient mutants showed that,compared with wild type,the mutant plants showed leaf wilting and even dry death,roots curled,root branch number decreased,and lateral root growth and development were hindered under drought conditions.Determination of physiological and biochemical indexes showed that the relative water content,chlorophyll content and net photosynthetic rate of the deficient mutants were significantly lower than those of the wild-type plants after drought stress,indicating that the drought resistance of Arabidopsis decreased after ARF10 gene was knocked out.

This study investigated the effects of arbuscular mycorrhizal fungi(AMF)inoculation on the physiological characteristics and the accumulation of active components in the medicinal tree peony Paeonia ostii Fengdan under drought stress,with the aim of providing a theoretical basis for utilizing AMF to enhance the drought resistance and medicinal quality of this species.Using P.ostii seedlings as experimental material,four treatments were established:well-watered control(CK),drought stress(DR),AMF inoculation under well-watered conditions(AMCK),and AMF inoculation under drought stress(AMDR).Indicators related to plant redox homeostasis(including superoxide dismutase(SOD)activity,proline and soluble sugar content),photosynthetic characteristics(including photosynthetic pigment content,gas exchange parameters,and chlorophyll fluorescence parameters),and the content of active components(such as total flavonoids,paeonol,and paeoniflorin)in the root bark were measured.The results showed that drought stress induced significant accumulation of malondialdehyde(MDA)and reactive oxygen species(ROS),with increases of 33.53% and 50.04%, respectively,while photosynthetic performance was markedly inhibited.This was specifically evidenced by significant decreases in net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),maximum photochemical efficiency(Fv/Fm),and photosynthetic performance index(PIabs).AMF inoculation effectively alleviated these adverse effects.It was found that inoculation not only significantly increased SOD activity by 6.36% and elevated the contents of osmoregulatory substances (soluble proteins, soluble sugars, and proline) by 23.72%, 53.31%, and 14.70%, respectively,but also reduced ROS levels,thereby enhancing cell membrane stability.A significant recovery was also observed in photosynthetic pigment content and photosynthetic and chlorophyll fluorescence parameters(Pn,Gs,Tr,Fv/Fm,and PIabs).Furthermore,under drought stress conditions,AMF inoculation further promoted the accumulation of secondary metabolites in the root bark,including total flavonoids,paeonol,and paeoniflorin,with increases of 18.67%, 11.39%, and 5.17%, respectively, compared with the DR treatment.In conclusion,it is demonstrated that AMF can effectively mitigate the physiological damage caused by drought stress in P.ostii by enhancing its antioxidant capacity,promoting the accumulation of osmoregulatory substances,and improving photosynthetic performance.Simultaneously,AMF boosts the content of secondary metabolites in the root bark.

To investigate the role of the BnMLP2 gene in drought tolerance in ramie,the BnMLP2 gene encoding a metallothionein-like protein in ramie was obtained by analyzing ramie transcriptome data using Zhongzhu-1 as the material.The BnMLP2 gene was screened and cloned from the ramie transcriptome data,and bioinformatics analyses were conducted,including sequence alignment,domain prediction,and subcellular localization prediction.Fluorescent Quantitative PCR was used to determine the expression profile of the BnMLP2 gene in different tissues of ramie and to explore its expression changes under drought stress.The BnMLP2 gene was introduced into Arabidopsis thaliana to construct transgenic plants.Under drought stress conditions,phenotypic,physiological,and biochemical differences between transgenic and wild-type Arabidopsis were compared,along with the expression of stress-related genes.The results showed that the open reading frame of the BnMLP2 gene in ramie was 243 bp in length,encoding 80 amino acids.BnMLP2 had the closest amino acid sequence homology to metallothionein(MT)or metallothionein-like protein (MLP) from Malus domestica,both belonging to the metallothionein family; it contained the PFAM01439 domain and belonged to class Ⅱ metallothionein,with a predicted subcellular localization in the cytoplasm.The BnMLP2 gene was expressed in all tissues of ramie,and its expression was significantly induced by drought,especially in stems.Under drought stress,transgenic Arabidopsis overexpressing BnMLP2 exhibited stronger drought tolerance compared to wild-type plants,as evidenced by significantly increased root length and fresh weight,enhanced antioxidant enzyme and γ-glutamylcysteine ligase (γ-GCL) activities,and accumulation of more proline (Pro),glutathione(GSH),glutathione disulfide (GSSG),and phytochelatins (PCs) to regulate intracellular ion homeostasis.The contents of malondialdehyde (MDA)and hydrogen peroxide (H₂O₂)in transgenic lines were significantly lower than in wild-type plants,at 55% and 80% of wild-type levels,respectively.In addition, the content of sodium and potassium ions in transgenic Arabidopsis under drought conditions was 4.4 times and 1.4 times higher than that of the wild type, respectively. Overexpression of BnMLP2 induced increased expression of three stress-related genes,AtMT1a,AtNCED3,and AtWRKY40,with maximum expression levels of 1.5,1.9,and 2.8 times those in wild-type plants,respectively.These results suggest that the BnMLP2 gene enhances the tolerance of Arabidopsis to drought stress.

Tiller-related traits are important characteristics of wheat plant type,which determine plant structure and affect grain yield.In order to understand the inheritance and drought resistance of tiller-related traits in wheat under different water conditions,and to excavate the loci related to tiller-related traits,240 wheat varieties (lines) were selected as the subjects of this study,based on the phenotypic identification of tiller angle,effective tiller number and yield per unit area under normal irrigation (NI) and drought stress (DS) conditions,and the comprehensive evaluation of drought resistance,combined with 90K gene chip,genome-wide association study (GWAS) was to identify genetic loci for tiller-related traits and to screen for superior germplasm.The tiller angle,effective tiller number and yield per unit area showed significant difference,and the coefficient of variation ranged from 0.07 to 0.33.According to D-value,the drought resistance of Zhongyou 206 was the best.A total of 54 stable genetic loci significantly associated with tiller angle and other traits were detected, distributed on all chromosomes except 3D, 4D and 5D. Three identical stable loci were commonly detected under both treatments, located on chromosomes 2B, 4B, and 6B. Additionally, four pleiotropic loci were commonly detected in different traits, located on chromosomes 2B, 2D, and 5B.At the same time,the haplotype analysis of Ra_c491_902 (R²=5.45%—17.91%),which was significantly correlated with tiller angle on chromosome 2B,showed that there were three haplotypes:TA-Hap1,TA-Hap2 and TA-Hap3,the haplotypes (lines) containing TA-Hap1 were mainly derived from Huanghuai winter wheat regain.Five candidate genes related to tiller angle were screened by screening the stable genetic loci detected under different treatments.Gene annotation of the genes selected on Ra_c491_902 showed that the genes encoding cytochrome P450 family protein can be used as important genes such as regulating tillering angle,plant drought resistance and defense,to explore the association between genes and phenotype,and lay the foundation for the genetic improvement of tiller-related traits in wheat.

To reveal the mechanism of drought resistance of different resistant rice during germination period,Rice drought-sensitive materials(Calrose,Jingning 10,Shanxing 86)and drought resistance materials(Farry,Songjing 3,Ningjing 36)were studied on the effects of simulated drought stress(15% PEG-6000)on the growth index,physiological indexes and corresponding gene expression of different rice seeds.The results showed that under normal conditions,there were no significant differences in the expression levels of growth indicators and stress-related genes between drought-sensitive and drought-resistant cultivars.However,changes in physiological indicators were shown that there were no significant differences in the activities of superoxide dismutase(SOD) and peroxidase(POD),the contents of soluble sugar(SS) and hydrogen peroxide(H₂O₂) among different genotypes.The contents of malondialdehyde(MDA) and superoxide anion($\mathrm{O}_{2}^{\bar{.}}$) in the drought-sensitive cultivar Shanxing 86 were significantly higher than those in other materials,and the contents of catalase(CAT),proline(Pro) and soluble protein(SP) of drought resistant Ningjing 36 were significantly higher than those of other materials as well.Under drought stress,the relative germination potential(RGP),relative bud length(RSL),germination drought resistance index(GDRI)and vitality index(VI)of germinating seeds increased by 0.03—0.07 percentage,0.32—0.39 percentage,0.12—0.18 percentage and 92.41%—108.39%,respectively;MDA and reactive oxygen species($\mathrm{O}_{2}^{\bar{.}}$,H₂O₂) contents in germinating seeds of drought-resistant cultivars decreased by 2.54%—61.64%,19.60%—46.30% and 35.61%—62.02% respectively compared with drought-sensitive cultivars.The contents of osmotic regulating substances(Pro,SS,SP) increased by 5.93%—18.29%,1.08%—7.97% and 3.47%—6.03% respectively.The activities of antioxidant enzymes(SOD,POD, CAT) were increased by 17.29%—33.12%,15.24%—76.06% and 14.68%—18.61% respectively.The relative expression levels of OsP5CS,antioxidant enzyme synthesis genes (OsALM1, OsPOX1, OsCATC) were up-regulated by 2.66%—182.31% and 57.14%—513.27%,0.38%—109.06% and 63.39%—184.25% respectively.Comprehensive analysis showed that drought stress inhibited the germination of rice seeds and affected the physiological characteristics of seeds and the expression of corresponding genes during germination.Under drought stress,vigor index(VI),peroxidase(POD)and peroxidase synthesis gene(OsPOX1)are the key indicators affecting rice seed germination,whether it is drought-resistant or drought-sensitive materials.In addition to the above indicators,soluble protein(SP),proline synthesis gene(OsP5CS)and catalase gene(OsCATC)are other key indicators affecting drought-resistant materials.Relative shoot length(RSL),hydrogen peroxide(H₂O₂)and superoxide dismutase gene(OsALM1)are other key indicators affecting drought-sensitive materials.

To elucidate the molecular mechanisms underlying peanut pod responses to water stress,this study employed pot experiments combined with transcriptomic analysis.Using well-watered conditions as the control, we systematically investigated the effects of periodic drought and waterlogging stress during the flowering-pegging stage on yield,quality,and gene expression in peanut pods. Results demonstrated that both drought and waterlogging stresses significantly reduced peanut pod yield(by 26.43% and 77.69%,respectively)and crude fat content in kernels (by 9.46, 6.71 percentage points,respectively).Transcriptomic analysis further revealed 1 525 and 1 382 differentially expressed genes(DEGs)in the drought-stress and waterlogging-stress groups compared to the control, respectively, with down-regulated expression being predominant in both sets of DEGs. Specifically, drought stress suppressed six key metabolic processes related to lipid and fatty acid metabolism in peanut pods,with 88.38% of associated genes showing downregulated expression,indicating that lipid metabolic disruption may be the primary cause of yield and quality reduction under drought. Waterlogging stress predominantly interfered with pod metabolism and defense functions by downregulating genes associated with catalytic activity,transmembrane transport,redox reactions,and biosynthesis of secondary metabolites.Moreover, KEGG enrichment analysis indicated that metabolic pathways and biosynthesis of secondary metabolites were significantly affected under both water stress conditions. Key gene validation via qRT-PCR corroborated the RNA-seq data, confirming the reliability of the transcriptomic findings. In summary, this research elucidates the molecular basis of peanut pod response to water stress at the transcriptome level, demonstrating that lipid metabolic disruption is the primary factor underlying yield reduction and quality deterioration under drought stress, whereas peanut pods mitigate the adverse effects of waterlogging mainly by modulating the expression of genes associated with redox homeostasis and metabolic pathways.

In order to explore the photosynthetic physiological response mechanisms of three summer maize varieties (Xundan 20, Jinbei 288 and Dika 667) which were commonly cultivated in arid and semi-arid areas to drought stress, these three varieties were treated under different drought stresses (including non-drought treatment (CK), light drought (LD) and heavy drought (HD)). Responses of net photosynthetic rate to light intensity (Pn-PAR) and net photosynthetic rate to intercellular CO₂ concentration (A-Ci) were estimated by the portable photosynthesis system Li-6400, and responses of chlorophyll fluorescence parameters to light intensity were measured by portable modulation chlorophyll fluorescence meter MINI-PAM, respectively. The results were as follows. As for all these three varieties, the response modes of Pn and stomatal conductance (Gs) to PAR were similar among these three maize varieties, and the responses of Pn to Gs shifted to left along the drought stress gradient. The initial chemical efficiency (CE) and photosynthetic capacity (Amax) were significantly lower under heavy drought treatment than under the other two treatments for each of the three varieties. Compared with the results under CK treatment, the non-photochemical quenching coefficient (qN) and the quantum yield of the regulatory energy dissipation (Y (NPQ)) were lower and the quantum yield of non-regulated energy dissipation (Y(NO)) was higher under LD or HD treatment for the two varieties of Jundan 20 and Dika 667; and the photochemical quenching coefficient (qP) was lower under HD treatment for the variety of Jinbei 288. Compared with the results under CK treatment, the maximum net photosynthetic rate (Pmax) and initial quantum efficiency (AQY) were a little higher under LD treatment for the variety of Jinbei 288. Compared with the other two varieties, the Pmax and AQY showed higher tolerance to drought stress by keeping relatively lower qQ and lower Y(NO) for the variety of Jinbei 288, and these results not only showed the greater tolerance of Jinbei288 to drought stress, but also provided reference for the screening of crop varieties for drought tolerance.

In order to study the effects of continuous drought treatment in whole growth period on cotton growing development and final yield,in this experiment,pot-culture method was taken and Xinluzao 19hao,Xinluzao 27hao and Xinluzao 54hao as materials,the treatments were light and moderate drought stress,then measured morphological indexes,physiological indexes and photosynthetic parameters at seedling stage,bud stage,blooming stage and boll opening stage,and investigated yield components at harvest time.Results showed:cotton height and stem diameter decreased with the strengthen of drought stress; The content of reactive oxygen species and antioxidant enzyme activities were great difference at different growth stage,correlation analysis showed that there were significant or extremely significant correlation between active oxygen content and antioxidant enzyme activity,indicted that antioxidant enzymes activity changed regularly with the content of reactive oxygen species,so as to eliminate the excessive oxygen species in vivo and prevent the damage of reactive oxygen species; The photosynthesis of cotton at bud stage decreased with the strengthen of drought stress,but increased at boll opening stage,except Xinluzao 27hao which possibly due to persistent drought treatment caused the different developmental stage of cotton at later growth stage; Drought stress reduced the yield per plant and fiber length of Xinluzao 27hao and Xinluzao 54hao,light drought stress had little effect on single boll weight,even played a role in promoting; There were four indexes of cotton at blooming stage had significant correlation with yield per plant,indicted that cotton blooming stage might be the key period which easy to be affected by environment and determined the final yield.

In order to clarify the effects of drought stress on the photosynthetic characteristics in flag leaf in the afternoon during grain filling stage and grain yield of winter wheat with different drought resistance,an experiment with two winter wheat cultivars and four water levels was conducted under the condition of rainproof pond cultivation in 2018—2019 and 2019—2020.The two winter wheat cultivars were Jinmai 47(JM47,strong drought resistance)and Yanzhan 4110(YZ4110,weak drought resistance).The four water treatments included severe drought(W1:65% MFC(maximum field water capacity)before sowing + 45%—55% MFC after jointing),moderate drought(W2:75% MFC before sowing + 55%—65% MFC after jointing),mild drought(W3:75% MFC before sowing+65%—75% MFC after jointing),suitable water supply(W4:75%MFC before sowing+75%—85% MFC after jointing).The net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO₂ concentration(Ci),transpiration rate(Tr),instantaneous water use efficiency(IWUE),maximum photochemical efficiency of PS Ⅱ (Fv/Fm)and actual photochemical efficiency of PS Ⅱ(ΦPS Ⅱ)in flag leaf from 14:00 to 16:00 during the early,medium and medium-late grain filling stage and the grain yield and its components at maturity were investigated.The results showed that both water and cultivars had significant effects on the photosynthetic and fluorescence characteristics in flag leaf in the afternoon during the grain filling stage and the grain yield at maturity of winter wheat.From the two-year average,compared with W4,the Pn,Gs and ΦPSⅡ in flag leaf in the afternoon during the grain filling stage under drought stress(W1,W2 and W3)respectively decreased by 2.07%—68.92%,-3.23%—50.00% and -1.89%—30.19% in JM47,and decreased by 7.71%—80.19%,11.11%—59.26% and 0—73.47% in YZ4110;the flag leaf Tr values in the afternoon during the medium grain filling stage in JM47 and YZ4110 respectively decreased by 6.30%—32.87% and 6.49%—41.74%,and the flag leaf Fv/Fm values in the afternoon during the medium-late grain filling stage decreased by 1.20%—18.52% and 2.50%—30.00%.In general,for all the above indexes,the decreasing amplitude for the same index was JM47<YZ4110.Compared with YZ4110,the Pn,Gs,ΦPSⅡ and Fv/Fm in flag leaf in the afternoon during the grain filling stage under drought stress(W1,W2 and W3)of JM47 respectively increased by 0.86%—64.89%,8.33%—36.36%,1.96%—184.62% and 1.25%—17.86%,and the grain yields of JM47 were respectively increased by 28.91%,8.06% and 5.40%.Except for IWUE,the flag leaf photosynthetic parameters in the afternoon during the grain filling stage were significantly and extremely significant correlated with grain yield,but the correlation indexes varied with variety and grain filling stage.For JM47,the correlation indexes between the grain yield and flag leaf photosynthetic parameters were highest for Pn,Gs and Fv/Fm during the medium-late grain filling stage,for ΦPSⅡ during the medium grain filling stage,and for Tr during the early grain filling stage.For YZ4110,the correlation indexes were highest for Pn,Gs and Tr during the early grain filling stage,for ΦPSⅡ during the medium grain filling stage and for Fv/Fm during the medium-late grain filling stage.In summary,drought stress decreased the photosynthetic function of flag leaf in the afternoon during grain filling stage and thus decreased the grain yield of winter wheat,the strong drought resistance variety could maintain better flag leaf photosynthetic characteristics in the afternoon during the grain the filling stage under drought stress condition,and significantly improved the ΦPSⅡ of flag leaf in the afternoon during the medium grain filling stage and the Pn,Gs and Fv/Fm of flag leaf in the afternoon during the medium-late grain filling stage,thereby increasing the grain yield.

Preliminary transcriptomic analysis identified ZmRAV1 as a candidate gene involved in maize's response to drought stress. To further investigate its function, this study cloned the ZmRAV1 gene, conducted bioinformatics analysis of its coding sequence, and overexpressed this gene in Arabidopsis thaliana. The function of ZmRAV1 was validated by assessing the phenotypes and physiological and biochemical indices of the transgenic Arabidopsis lines under drought conditions. The results showed that the ZmRAV1 gene had a total length of 1 176 bp and encoded 389 amino acids.It had the highest proportion of irregular coils in its secondary structure and was a hydrophilic protein that did not contain signal peptides and was non transmembrane.Subcellular localization indicated that the protein was located in the nucleus.ZmRAV1 exhibited high conservation across different species.Phylogenetic analysis indicated that ZmRAV1 shares the closest evolutionary relationship with its homolog in Miscanthus sinensis, showing a high degree of homology. After drought stress treatment,the root length of Arabidopsis thaliana lines overexpressing ZmRAV1 during germination was significantly higher than that of wild-type (WT)lines.In the seedling stage,WT showed withering or even death after drought stress,while the survival rate was lower than that of overexpressing lines.Moreover,the POD and SOD activities of ZmRAV1 overexpressing lines were higher than those of WT after drought treatment,indicating that overexpression of ZmRAV1 gene could enhance Arabidopsis thaliana's resistance to drought stress.

In order to study the effect of drought stress on physiological characteristics of grafting flue-cured tobacco,using KRK26 as scion, KRK26,K326 and Anyan 2 as rootstock,analysing and discussing root morphology, plant morphology and physiological indexes of resistance in pot culture under different treatment. The results indicated that under drought stress conditions at early period, the relative content of chlorophyll (SPAD readings) decreased, while the content of proline, superoxide dismutase (SOD) activities, catalase (CAT) activities and peroxidase (POD) activities in flue-cured tobacco demonstrated an increasing trend. The root length,surface area,plant height,stem girth, node spacing and LAI of the grafted tobacco plants showed a decreasing trend,the content of proline continued to increase in both grafted seedlings and non-grafted seedlings with the aggravation of drought stress when tobacco leaves were turning to mature, whereas, the SPAD readings, SOD activities, CAT activities and POD activities all demonstrated a decreasing trend. The speed of decreasing in different root grafted was slower than that in own root grafted. Compared with KRK26/K326 and KRK26/KRK26, KRK26/Anyan 2 had greater parameters under drought stress, but the SPAD readings did not have significant difference. All the results showed that less damage was made to KRK26/Anyan 2 than KRK26/K326 and KRK26/KRK26 under drought stress, and KRK26/KRK26 suffered the most serious damage. According to correlation analysis, there was a certain correlation between morphological indexes and resistance indexes of grafting flue-cured tobacco. In conclusion, there were obvious differences among grafted tobacco in physiological characteristics, and there response to soil drought. The order of drought resistance was KRK26/Anyan 2, KRK26/K326 and KRK26/KRK26 in turn from strong to weak, based on the main root morphology,plant morphology,physiological characteristics under drought stress.

In order to explore the effects of growth and aging characteristics of peanut under drought and salt stress,using Huayu 25 as material,potted experiment was carried out to study the change of peanut growth and aging characteristics due to the stress of drought and salt at flowering stage.The results showed that drought treatment (D),salt stress treatment (S),drought and salt stress (DS) increased the content of soluble protein,soluble sugar,free amino acid,proline,O₂^· and MDA. S treatment and DS treatment reduced the activity of SOD,POD and CAT in the leaves,which continued to decrease as time prolonged. But D treatment enhanced SOD and CAT activity in the leaves. After 10 days of rehydration,the content of soluble sugar,soluble protein,free amino acid,proline,O₂^· and MDA of D treatment reduced compared with the numerical values which detected before rehydration.D treatment had no significant difference with CK,including activity of SOD and POD and content of O₂^·,MDA,soluble sugar,free amino acid,proline. However,the difference of the activity of SOD,POD,CAT of DS treatment was significant compared with S treatment,so did the content of O₂^· and MDA.In the harvest time,single plant yield and the kernel rate of D treatment had no significant difference with CK,but DS treatment had significant difference with S treatment. Data from DAT9 showed that drought and salt stress had no significant interaction with soluble sugar,soluble protein,free amino acid and proline content in leaves. However,there was significant interaction of SOD,POD,CAT activity and O₂^·,MDA content between drought stress and salt stress. The interaction between drought stress and salt stress inhibited the activity of SOD,POD and CAT and exacerbated the peroxidation of plant cell membranes. Eventually it decreased the single plant yield and the kernel rate. Therefore,peanuts planting under salt stress should avoid the drought at flowering stage to reduce the harm of salt stress,drought stress and the interaction between salt stress and drought stress.

Tremendous impact of drought on agricultural production,research drought stress on physiological and yield,will provide the basis for soybean production in arid areas.In this paper,the use of plastic storage box drought stress test were studied photosynthetic physiology,leaf osmotic adjustment and antioxidant enzyme composition and biomass yield on the soil water into arid(45%-55% of the maximum water holding capacity of soil field) two horizontal and humid(80%-100% field soil water holding capacity,CK).The results showed that drought stress soybean net photosynthetic rate,stomatal conductance and transpiration rate decreased significantly,water use efficiency increased;drought stress on leaf peroxidase(POD) and superoxide dismutase(SOD) no significant effect on the content;malondialdehyde(MDA) content increased by 25.00% to reach a significant level;the amount of reducing sugars and total soluble sugars increased by 47.09% and 47.16%,respectively.Drought stress on soybean plant height,node number,stem diameter,aboveground biomass,yield decreased significantly.Under drought stress,soybean stomatal conductance decreased significantly,severely affected the supply of CO₂,reducing the net photosynthetic rate,so that the decline in soybean photosynthetic metabolism.Plant material can be adjusted to maintain the moisture permeation through the cell.Although soybeans can maintain cell moisture through osmotic adjustment substances,drought still inhibits normal plant growth and decreases soybean biomass and yield.

To study the physiological effects of different degrees of drought on soybean cultivars in different development periods. Two soybean cultivars with different drought resistances were taken as the experiment materials to study the effects of drought stress on the resistance index and physiological characteristics of soybean in different growth periods, and to explore the physiological mechanism of soybean response to different drought intensities at different developing stages in pot culture. Four treatments were set up:continuous mild drought stress (T1), continuous moderate drought stress(T2), drought stress in full seed stage (T3) and without drought stress(CK). The results showed that under drought stress, the chlorophyll contents of both soybean cultivars increased, and Jindazaochun 2 was more obvious at early stage, but it was less than that of Jinda 74 at grain-filling stage. Under continuous mild drought stress and continuous moderate drought stress, the MDA content of Jindazaochun 2 at different growth stages significantly increased, while the POD and MDA contents of Jinda 74 significantly increased under continuous moderate drought stress. At the branching stage, the content of reducing sugar in Jinda 74 decreased significantly during moderate drought. In the Granulation stage, the reducing sugar content of soybean leaves in Jindazaochun 2 was significantly increased, Jinda 74 was only reduced under drought treatment in the Granulation stage. At flowering stage, reducing sugar content reduced in Jindazaochun 2, but increased significantly in Jinda 74. It was found that drought had a great influence on reducing the plant height, node number, stem diameter of both cultivars. The decrease in plant height and stem diameter of Jinda 74 was more obvious. The resistance of Jinda 74 to drought was higher than that of Jindazaochun 2, which was related to the reduction of plant height and water consumption under continuous drought conditions. The results will provide a basis for comprehensive understanding of the soybean resistance to drought stress.

In order to understand the dynamic rules of sugars, starch, protein and trace elements of different types of wheat during grain filling stage under drought stress, and to identify the difference of nutriment between drought and irrigation in the process of grain-filling by high-yield wheat, high-quality wheat and water-saving wheat, the wheat varieties of Jimai 325, Jimai 418 and Jimai 323 in the North of Huang-Huai Region were used as experimental materials. The plants heading and flowering on the same day were selected for marking, and the grains of each variety were taken every 6 days after 7-31 days after anthesis. The effects of drought during grain filling on the contents of total soluble sugar, sucrose, glucose, fructose, protein, Fe, Zn, Mn, Cu, amylose and amylopectin accumulation, starch accumulation rate and the activities of key enzymes in starch synthesis were studied. The results showed that the content of sucrose and glucose in wheat grains was significantly decreased under drought stress, and the effect on fructose content was relatively small, and the sucrose and fructose of high-yielding variety Jimai 325 were less affected by drought in the filling process. Drought stress decreased the content of amylopectin and total starch in wheat grains, but had relatively little effect on the content of amylose. The effect of drought stress on starch content of high-yield and high-quality varieties was significantly greater than that of drought-tolerant variety Jimai 418. The activity of starch synthase was increased in the early and middle stages of filling stage under drought stress, and decreased rapidly in the middle and late stages compared with irrigation control. The content and accumulation of four mineral elements in wheat grains were Mg>Fe>Zn>Mn. With the progress of grain filling, the content of trace elements showed a downward trend. The accumulation of Fe, Zn and Mg in grains of Jimai 325 was higher. The difference of nutrient accumulation in grain filling process of different types of wheat under drought conditions were studied to provide theoretical data and reference basis for optimizing cultivation measures and realizing high quality, high yield and water saving of special wheat.

In order to explore a fast and efficient way to screen drought-resistant varieties of winter wheat, and to select drought-resistant winter wheat varieties. Six winter wheat varieties, Yannong 999, Taimai 1918, Jimai 22, Jimai 23, Taishan 27 and Shiluan 02-1 were used in this study. Normal water treatment(75% relative soil water content), mild drought treatment(55% relative soil water content) and moderate drought treatment(40% relative soil water content) were arranged to explore the chlorophyll fluorescence parameters, biomass, root-shoot ratio, SPAD, superoxide dismutase(SOD) activity, malondialdehyde(MDA) content and their correlations. Results showed that, compared with other varieties, under drought stress, Taimai 1918 obtained the highest drought resistance coefficient(DTC). The smallest reduction of root to shoot ratio, SPAD value, photosystem Ⅱ maximum photosynthetic efficiency(Fv/Fm), photosystem Ⅱ actual photosynthesis efficiency(φPSⅡ), relative electron transfer rate(ETR), SOD, and the largest increasing in non-photochemical quenching(NPQ) and minimal increasing in MDA content were observed in Taimai 1918. The order of drought resistance of 6 winter wheat varieties was Taimai 1918 > Yannong 999 > Jimai 22 > Jimai 23 > Taishan 27 > Shiluan 02-1. The chlorophyll fluorescence parameters were significantly correlated with drought resistance coefficient, SOD activity and MDA content. Sum up, the drought resistance in Taimai 1918 was strongest, and chlorophyll fluorescence parameters can be used for screening drought-resistant winter wheat varieties at seedling stage.

In order to clarify the drought resistance and drought resistance mechanism of Allium polyrhizum in Inner Mongolia grassland,potted water control method was adopted.Two gradients were set,75% of the maximum field water capacity as the control(CK),and 25% of the soil relative water content under 30 days of drought stress.The root morphology,physiological characteristics and leaf photosynthetic characteristics of Allium polyrhizum from different sources were analyzed under drought stress. The result showed that Allium polyrhizum in Siziwang Banner compared with the Chifeng and Ordos was remaining relatively high root surface area,root volume and root length 0-0.5 mm in diameter. Allium polyrhizum root growth was relatively less affected by drought stress,chloroplasts were relatively stable and strong drought resistance in Siziwang Banner. Drought stress significantly decreased the above ground biomass,below ground biomass and total biomass of Allium polyrhizum in Chifeng and Ordos,but had no significant effects on Siziwang Banner(P>0.05). The Pn,Tr,Gs,Ci and leaves relative water content of Allium polyrhizum seedlings were significantly decreased and the relative permeability of cytoplasmic membrane was markedly increased under the whole drought stress treatment. Drought stress induced stomatal closure of Allium polyrhizum leaves and reduced transpiration to decrease water loss.The root characteristics,relative water content,chlorophyll and photosynthetic characteristics of Allium polyrhizum in different sources were certain differences under the same treatment. In general,the effect of drought stress on Allium polyrhizum in Siziwang Banner was relatively weak,it was indicating stronger drought tolerance.

In order to explore the genetic basis of drought resistance and guide drought resistance breeding, mapping of QTL associated with drought resistance at germination stage of foxtail millet was done. An F₂ segregating population was constructed using 100 individuals derived from a cross between Shanxi 2010 and K359×M4-1. A genetic linkage map was constructed based on 2b-RAD sequencing, which was then combined with the phenotypic trait of drought resistance for QTL mapping. The results showed that drought resistance at germination stage of foxtail millet was a complex quantitative trait and controlled by multiple genes. A genetic map containing 583 SNP makers was constructed by 2b-RAD of parents and F₂ population. The map covered 9 chromosomes of foxtail millet, with an average number of 64.8 and an average genetic distance of 0.97 cM between markers. A total of 3 QTLs were identified:qSIDR-5a, qSIDR-6a and qSIDR-6b, located in foxtail millet chromosome 5 and 6, respectively, which explained 12.4%-14.3% of phenotypic variation. Among them, phenotypic contribution rate of qSIDR-5a was the highest, which explained 14.3% of phenotypic variation. These QTLs were not included in the same chromosome interval as the identified drought resistance related QTLs of foxtail millet, and thus were described as new candidate gene loci associated with germination stage drought resistance.These QTLs can be used for fine mapping and gene cloning, as well as molecular regulation mechanism of drought resistance of foxtail millet.

The purpose of this study was to explore the effects of different drought stress levels on maize growth traits and yield in the semi-arid region of Northeast China, and to lay a theoretical foundation for further research on the physiological mechanism of maize drought resistance.Three kinds of maize varieties with different drought tolerance were selected and five water gradients of normal water supply(CK), light drought(LS), moderate drought(MS), severe drought(SS)and lethal(S)were set at maize jointing, tasselling and filling stages, respectively. The effects of different drought stress on the growth traits and yield related indexes of three maize varieties were comprehensively analyzed. The plant height, ear position and dry matter weight of maize decreased with the increasing of drought degree, but the stem diameter had no significant difference with the increasing of drought degree. The plant height, ear position and dry matter accumulation of maize variety Jinqing 707 was the highest, followed by Nendan 19 and Fudan 16. During tasselling stage, the spike characters of maize changed most obviously under drought stress, and the maize yield was the lowest under severe drought, and no yield under continuous drought.Under the same drought degree, the worse the drought tolerance of maize varieties, the greater the yield reduction. The specific performance of maize yield is Jinqing 707 > Nendan 19 > Fudan 16.A comprehensive analysis of multiple indicators shows that tasselling stage is the key period of water requirement of maize, which is easily affected by drought stress. At the same time, it is pointed out that drought stress or serious degree of drought stress in tasselling stage is the main factor leading to the decrease of maize yield.

Chalcone synthase(CHS)is the initial and crucial enzyme in the flavonoid biosynthesis pathway,responsible for the synthesizing of metabolites such as flavones,flavonols,isoflavones,and anthocyanins,which play a vital role in enhancing plant stress resistance.In order to explore the role of CHS genes in the drought stress response of oat seedlings,it identified a CHS gene from the full-length transcriptome data of oats,named AsCHS.Gene cloning,bioinformatics analysis,subcellular localization,and expression pattern analysis were conducted.The results showed that the AsCHS gene encoded a protein composed of 398 amino acids and had a CHS family-specific tag sequence.This protein was hydrophobic and unstable.It was a non-transmembrane protein and was located in the nucleus and cytoplasm.Secondary structure prediction showed that AsCHS was mainly composed of α-helices and random coils.The analysis of the cis-acting elements within the promoter region revealed that the gene contained cis-elements associated with drought stress response and multiple hormone signaling pathways.Phylogenetic tree analysis showed that AsCHS was closely related to its counterparts in Lolium perenne,Poa annua,and Deschampsia antarctica.Subcellular localization indicated that the AsCHS protein was localized in the nucleus and cytoplasm.Compared with the control group,the expression pattern of AsCHS in oat seedlings under drought stress changed from fluctuating expression to incremental expression with different germination time,shifting from the highest expression level in roots to the highest in leaves,with significant differences observed in leaves expression.It laid a foundation for elucidating the function of AsCHS in the drought stress response of oats.

In order to explore the effect of grain size and sowing depth on emergence and seedling growth,determining suitable grain size and sowing depth in mechanization of summer maize production of Southwest Hilly Area.In the split-plot design,using Zhenghong 505 as the test material,3 kinds of grain size was assigned to the main plot,and 3 sowing depth(2,6,10 cm) to the subplot,emergence rate of maize,seedling quality,yield and yield components have been investigated in drought condition.The results showed that compared with small grain,large grain had higher emergence rate,the seedling was more haleness and grew better in drought,and there was a certain effect of increasing yield ultimately;Shallow sowing(2 cm) was conducive to the emergence,and the growth vigor of the seedlings of 6 cm sowing depth was best just when emerging,then the 10 cm depth of the seedling grew gradually strong,and obviously better at the 5 leaf period(large and medium grain)-7 leaf period(small grain) than shallow sowing treatment,which also showed a certain increase in yield.Therefore,in the dry land or dry season,choosing large grain and suitable sowing depth in maize production can effectively better sthong seedlings,improve the resistance of drought,and achieve the purpose of producing income insurance.

A Receptor-like kinase(RLK)gene, OsSIK1,plays important roles in drought stress-tolerance in rice,through the activation of the antioxidative system.To make maize plants have much more drought resistance genes and further to obtain drought tolerance maize germplasm.In this study, OsSIK1 gene of rice was transformated into maize inbred Zheng 58 plants by pollen-mediated method.First,transgenic plants in T₁,T₂ and T₃ were detected by Kanamycin resistance screening,PCR and Southern Blotting,transgenic plants were obtained from T₁ and pure transgenic lines was obtained from T₃.Next,drought resistance analysis to transgenic maize plants and non-transformation control plants were conducted under the condition of 16.1% PEG drought stress.The results showed that compared with non-transgenic plants,the seedling leaf relative water content,chlorophyll content and SOD activity of transgenic plants were increased by 7.4%-19.8%,11.3%-106.9% and 45.8%-93.4%,respectively;furthermore,the relative conductivity and MDA content were decreased by 35.4%-58.1%,and 25.7%-50.4%,respectively.All the physiological indexes under the drought stress proved that transgenic OsSIK1 gene improved the drought resistance of transgenic maize plants,further analysis found that there were significant differences on drought tolerance between 5 transformed lines and their control groups,and their performance of field were superior to that of non-transgenic maize seedlings.At last,5 transgenic maize inbred lines were obtained,which suggested that genetically modified maize has improved the drought resistance by introducing foreign OsSIK1 gene of rice.

This study provides a good foundation for further elucidating the function and mechanism of AhPLDα1 and AhPLDα2 in responding to drought stress in peanut.The full-length CDS sequences of AhPLDα1 and AhPLDα2 were cloned from Jihua 4 peanut leaf with ABA treatment using RT-PCR.The AhPLDα1 and AhPLDα2 gene fragments were inserted into the expression vector pBar-F3 by forward ways.These constructs were transformed into Agrobacterium tumefaciens GV3101 by freeze-thawing method and then introduced into wild-type Arabidopsis thaliana using modified floral-dip method.Under the condition of drought,the authors observed phenotypic changes of wild type and transgenic plants.Colony PCR and enzyme digestion results showed that,the plant overexpressing recombinant plasmid pBar-AhPLDα driven by CaMV35S promoter was successfully constructed.Glyphosate resistance screening,PCR detection and gene expression analysis showed that the positive transgenic plants were obtained.Under water deprivation,overexpression of AhPLDα1 and AhPLDα2 in transgenic Arabidopsis plants resulted in significantly enhanced tolerance to drought stress.In conclusion, AhPLDα1 and AhPLDα2 have a certain relation with drought stress signal transduction in transgenic Arabidopsis plants,and are potential candidate genes on the way to modified crop drought resistance.

bZIP transcription factors are widely found in plants and play an important role in regulating plant growth and development and abiotic stress response.In order to explore the functional role of bZIP transcription factor in maize drought stress response,transcriptome sequencing technology was used to analyze the expression changes of transcription factors in maize seedlings treated with drought stress for 5 days and rehydration for 3 days,and a bZIP transcription factor(ZmbZIP26)was screened from transcriptome data in response to drought and rewatering treatment.Co-expression network analysis revealed that ZmbZIP26 was at the core node of network regulation.The gene contained a 558 bp open reading frame encoding 185 amino acids,which was a hydrophilic protein.Phylogenetic tree and conserved sequence analysis showed that ZmbZIP26 protein had high homology with homologous proteins of sorghum and Miscanthus,and also had the same conserved motifs at the same amino acid positions.Cis-element analysis showed that the upstream 2 000 bp region of the ATG site contained drought response elements,hormone response elements and light response elements.qRT-PCR analysis showed that ZmbZIP26 was a constitutively expressed gene,which was highly expressed in young stems,female panicles and roots.ZmbZIP26 positively responded to drought,high temperature,high salt and nitrogen stress and the process of restoring,which might play an important role in the process of plant resistance.Subcellular localization analysis revealed that ZmbZIP26 was a nuclear protein localized in the nucleus.Protein interaction prediction showed that ZmbZIP26 might interact with zinc finger protein,serine protein,Ca-dependent protein and glutathione transfer protein to construct a regulatory network,which cooperatively regulated maize growth and development and stress response process.

Foxtail mille is a C₄ gramineous crop with drought resistance, barren-tolerance, wild adaptability and high adverse resistance. To reveal the role of the genes expression characteristics under light and stress of foxtail millet, the genes related to abiotic stress were explored in this experiment. A PPDK gene, named as SiPPDK2, was identified in foxtail millet genome by bioinformatics method. SiPPDK2 was located on chromosome 3 in foxtail millet genome, which contained 18 introns. It contained 3 transcripts and primary alternative transcript encoding 945 amino acids residues. Subcellular localization predictions indicated that SiPPDK2 was mainly localized in chloroplasts. Functional domain and multiple sequence alignment analysis revealed that SiPPDK2 protein had a more closely relationship with PPDK proteins in maize, sorghum and rice. RT-PCR analysis showed that the expression of SiPPDK2 at its seedling stage was induced by PEG, ABA, salt and low temperature treatments. Further studies indicated that SiPPDK2 was involved in drought stress and different light intensity at the jointing, heading and filling stage, in which the expression was significantly increased under the drought condition at heading and filling stages and under the low light condition at jointing and filling stage. cis-elements analysis revealed that hormonal, stress, light, and other growth-related responses cis-elements were present in the promoter region of the SiPPDK2. The results speculated that SiPPDK2 is involved in the response to abiotic stress in foxtail millet.

Calcium-dependent protein kinases (CDPKs) function as Ca²⁺ sensor in various plant physiological processes.CPK10 was one member of CDPK family.In order to investigate the molecular mechanisms of CPK10 and it's high homology CPK30 in response to stress,cpk10×cpk30 double mutant was firstly constructed.The phenotypes in response to various stress were detected,and the RT-PCR method was used to analyzed the two genes expression.The results showed that there was no difference in the seed germination stage between double mutant and wild-type plants in the treatment of drought,salt and ABA.In the mature stage,double mutant exhibited no difference to drought stress compared with wild-type and single mutant.Nevertheless,the expression levels of RD29A was decreased in the double mutant and showed opposite trend in wild-type and single mutant during drought stress.The expression of ABA-responsive gene OST1 was enhanced obviously in double mutant after drought stress 0.5 h.The cpk10×cpk30 double mutant was successfully obtained.Our data indicated that CPK10 and CPK30 might be involved in ABA-dependent signal transduction pathway,and showed redundant functions.

To identify the miRNAs and their response regular patterns to salt stress and drought stress,rice seedlings at three leaves stage were used to quantify the expression of miRNAs and their targets when treated with salt and drought stresses at 0,3,6,12,24,48 h by qRT-PCR. The results demonstrated that expression patterns of miRNAs were affected by space-time and tissues under salt and drought treatments. Further analysis indicated that the expressions of miR156,miR164,miR167,miR169, and miR171 upregulated in roots with time and expressions of miR159,miR160,miR319,miR398, and miR1848 downregulated at 3 h and then upregulated when treated with salt(NaCl). And the 10 miRNAs were performed their lowest expressions in shoots at 3 or 6 h under NaCl treatment. On the other hand,the expressions of the most of the 10 miRNAs downregulated in roots generally and expressions of miR156,miR159 and miR160 downregulated in shoots and the expression patterns of miR167,miR169,miR319,miR398, and miR1848 down regulated first and then upregulated when treated with drought(PEG). Furthermore,expression patterns of targets were also affected by space-time and tissues. And only few expression patterns of the 10 miRNAs negatively correlated with its target,which implied the complexity of the regulation network of miRNA and its target in response to stresses.