摘要：

为揭示魔芋感染白绢病对魔芋防御酶活性及接种部位叶际微生态的影响,利用防御酶活性试剂盒(分光光度计法)和高通量测序技术分别对魔芋接种齐整小核菌(Sr)后魔芋叶柄过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)、多酚氧化酶(PPO)和几丁质酶(CHI)活性及叶际细菌和真菌群落结构及其多样性进行了研究。结果表明,魔芋接种Sr后防御酶活性均显著提高,其中CAT和PPO活性在接种Sr第3天达到峰值,分别为对照组的6.34,5.29倍,POD活性持续显著提高,至第6天时活性为对照组的36.98倍,SOD活性接种Sr后约为对照组的1.91倍,CHI活性接种Sr后约为对照组的5倍。叶际微生物组分析表明,与健康魔芋相比,魔芋接种Sr后叶柄叶际细菌群落的多样性与丰富度指数无显著差异,但丰富度指数呈持续下降的趋势;魔芋接种Sr第1天叶柄叶际真菌群落的多样性与丰富度指数无显著差异,接种Sr第3天真菌群落多样性指数无显著差异,丰富度指数显著降低,接种Sr第6天多样性指数和丰富度指数均显著降低。健康魔芋叶柄叶际细菌群落优势菌群为未分类的肠杆菌科、动性微杆菌属和假单胞菌属,真菌群落优势菌群为茎点壳孢属、小不整球壳属、枝孢霉属;接种Sr第1天魔芋叶柄叶际细菌群落优势菌群为肠杆菌科和泛菌属,至接种Sr第3天和第6天叶际细菌群落优势菌群为产碱杆菌科,而真菌群落优势菌群则变为核盘菌属。接种Sr和健康魔芋叶柄叶际细菌群落功能通路主要包括次生代谢物合成途径、多样性环境下的微生物代谢、ABC运输和双元组分系统等代谢途径。健康魔芋叶柄叶际真菌群落主要包含内生真菌-粪腐生物-地衣寄生物-凋落物腐生物-植物病原菌-土壤腐生物-木腐生菌(31.29%)、植物病原菌(27.68%)、动物病原菌-内生真菌-地衣寄生菌-植物病原菌-木腐生菌(20.27%)等10类功能类群,随着接种Sr时间的延长真菌功能类群逐渐单一,真菌-叶腐生菌-地衣寄生菌-地衣化植物病原菌-木腐生菌功能类群相对丰度持续增加。联合分析表明,POD、PPO、CAT和CHI活性与多数叶际细菌呈正相关;POD和CAT活性与部分叶际真菌呈负相关,POD和SOD活性与小核菌属呈正相关。

关键词: 珠芽魔芋, 白绢病, 叶际微生物, 防御酶活性

Abstract:

To reveal the effects of konjac infection with southern blight disease on the defense enzymes and the phyllosphere microorganism of petiole,the activities of catalase (CAT),peroxidase (POD),superoxide dismutase (SOD),polyphenol oxidase (PPO),and chitinase (CHI) in konjac petioles after inoculation with Sclerotium rolfsii (Sr) were determined using a defense enzyme activity kit (spectrophotometer method),and the structure and diversity of phyllosphere bacterial and fungal communities were investigated using Illumina high-throughput sequencing.The results indicated that the defense enzyme activities in konjac were significantly enhanced after Sr inoculation.Specifically,the activities of CAT and PPO peaked on the third day after Sr inoculation,reaching 6.34 and 5.29 times that of the control group,respectively.The activity of POD continued to increase significantly until the sixth day,reaching 36.98 times that of the control group.The activity of SOD was approximately 1.91 times that of the control group after Sr inoculation,while the activity of CHI was about 5 times that of the control group after Sr inoculation.Analysis of the phyllosphere microbiome revealed that,compared to healthy konjac,the diversity and richness indices of bacterial communities in the leaf petiole phyllosphere showed no significant differences after Sr inoculation,but the richness index exhibited a continuous downward trend.For fungal communities in the leaf petiole phyllosphere,there were no significant differences in diversity and richness indices on the 1st day after Sr inoculation.By the 3rd day,the fungal community diversity index showed no significant difference,while the richness index significantly decreased.By the 6th day,both the diversity and richness indices of the fungal communities were significantly reduced. In healthy A. konjac, the dominant bacterial genera in the petiole phyllosphere were unclassified Enterobacteriaceae, Planomicrobium, and Pseudomonas, while the dominant fungal genera were Phoma, Plectosphaerella, and Cladosporium. On day 1 after Sr inoculation, the dominant bacterial genera shifted to Enterobacteriaceae and Pantoea. By days 3 and 6, the dominant bacterial genus became Alcaligenaceae, and the dominant fungal genus shifted to Sclerotinia. The functional pathways of bacterial communities in the leaf petiole phyllosphere of both Sr-inoculated and healthy konjac primarily included secondary metabolite biosynthesis pathways,microbial metabolism in diverse environments,ABC transport,and two-component system metabolic pathways.The fungal communities in the petiole phyllosphere of healthy konjac mainly consisted of ten functional groups,including endophytes-saprotrophs-lichen parasites-litter saprotrophs-plant pathogens-soil saprotrophs-wood saprotrophs (31.29%),plant pathogens (27.68%),and animal pathogens-endophytes-lichen parasites-plant pathogens-wood saprotrophs (20.27%).As the duration of Sr inoculation increased,the functional groups of fungi gradually became more homogeneous,with the relative abundance of the functional group comprising fungi-leaf saprotrophs-lichen parasites-lichenized plant pathogens-wood saprotrophs continuously increasing.Correlation analysis revealed that the activity of POD,PPO,CAT,and CHI were positively correlated with most phyllosphere bacteria.The activity of POD and CAT activities were negatively correlated with some phyllosphere fungi,while the activity of POD and SOD were positively correlated with the Sclerotium.

Key words: Amorphophallus muelleri, Southern blight disease, Phyllosphere microorganism, Defense enzyme activity

中图分类号: 

• S436.32