摘要： 为揭示小麦促分裂原活化蛋白激酶（MAPK）级联途径组分基因介导植物抵御低磷逆境的功能，以TaMAPKK3为对象，利用生物信息学技术分析其分子特征；通过设置低磷处理，检测小麦中TaMAPKK3基因的表达模式；将供试基因融合至双元表达载体pCAMBIA3301启动子下游，利用农杆菌介导法遗传转化烟草，通过qRT-PCR筛选出超表达TaMAPKK3基因的烟草植株；以转基因烟草为试验材料，通过测定低磷条件下植株的生长状态、光合参数以及含磷量等，鉴定TaMAPKK3介导植株抵御低磷逆境的功能。结果表明，TaMAPKK3编码阅读框1 572 bp，编码523个氨基酸残基，蛋白分子量58.508 ku，等电点为5.72。编码蛋白含有典型MAPKKs家族蛋白结构域，在其C端含有核转移因子结构域（NTF2），归属于MAPKKs家族中的B亚组；系统进化分析显示，TaMAPKK3与乌拉尔图小麦TuMAPKK6具有相似的进化途径；与正常供磷相比，低磷处理下，TaMAPKK3表达量随处理时间的延长呈现上调表达趋势，且在处理27 h转录丰度最高，进行复磷处理后供试基因转录本减少，在复磷处理27 h后转录丰度恢复初始状态；低磷处理下，超表达TaMAPKK3烟草株系较野生型长势增强，植株鲜质量和干物质积累量显著提高，植株根系发育较好，光合功能得到改善，磷素累积量显著增多。综上，TaMAPKK3在转录水平上对低磷逆境产生应答，过表达该基因增强植株抵御低磷胁迫的能力。

关键词: 小麦, TaMAPKK3基因, 低磷胁迫, 磷吸收, 根系建成

Abstract: In order to explore the wheat MAPK gene in improving the plant low-Pi stress tolerance,the molecular characterization of TaMAPKK3 was analyzed through bioinformatics technology. In addition,the expression pattern of TaMAPKK3 upon low-P treatment was evaluated;the target gene was integrated downstream of the promoter binary expression vector pCAMBIA3301 and subjected to tobacco transformation using Agrobacterium -mediated method. The tobacco lines overexpressing TaMAPKK3 were detected by qRT-PCR; using the transgenic tobacco as materials,based on measurements of growth traits,and physiological parameters and phosphorus content in plants,the gene function in mediating plant low-P stress capacity was identified.The results indicated that TaMAPKK3 contained an open reading frame of 1 572 bp,which encoded 523 amino acids with molecular weight 58.508 ku and isoelectric point 5.72. The encoded protein contained a typical domain shared by the MAPKKs family proteins and a nuclear transfer factor domain (NTF2) at the C-terminal position. The results suggested that it belonged to the B subgroup of the MAPKKs family. Phylogenetic analysis showed that TaMAPKK3 had a similar evolutionary pathway with TuMAPKK6 of Urartu wheat. Compared with that under normal P condition,the expression level of TaMAPKK3 was increased under low-P treatment and the transcriptional abundance was the highest at 27 h after treatment. The transcripts of the tested gene were decreased under the normal P recovery treatment and restored to its original amounts at 27 h after the recovery treatment. Compared with wild type (WT),the tobacco lines overexpressing TaMAPKK3significantly increased on the growth traits,fresh weight,dry matter accumulation and the root development,and displayed improved photosynthetic function and the phosphorus accumulation. Together,the results revealed that TaMAPKK3 responds to low-P stress at the transcription level,whose overexpression enhances the plant adaptation to P deprivation condition.

Key words: Wheat, TaMAPKK3 gene, Low-P stress, P uptake, Root system establishment

中图分类号: 

• Q78

• S512.03