HvEXPB7介导的西藏野生大麦耐旱机理研究

Drought is a major limiting factor for crop production, root hair is an important organ in uptake water and nutrients, and plays an important role in drought tolerance. In our previous study, the drought tolerance-related root hair development-regulated gene, HvEXPB7, was isolated from Tibetan wild barley XZ5, and it was cloned and preliminarily validated. On this basis, the following work will be carried out: (1) study of gene tissue localization using HvEXPB7 promoter-GUS/GFP fusion method; (2) analyze of plant root hair growth dynamic, ion fluxes, ionome, photosynthetic parameters and growth performance impact by HvEXPB7 using transgenic over-expression, RNAi and BSMV-VIGS technologies; (3) study of expression relationship between HvEXPB7 and the reported root hair growth-related genes, screen for interacting genes of HvEXPB7, and validate by yeast two hybrid and bimolecular fluorescence complementation; (4) define the expression relationship of different hormone signaling and HvEXPB7 as well as its interacting genes. The research aims to illuminate the molecular mechanism of root hair growth regulated by HvEXPB7, uncover the drought tolerance mechanism of XZ5 mediated by HvEXPB7, offering novel candidate genes and theoretical basis for breeding drought-tolerant barley varieties.

干旱是限制作物产量的一个重要因素，根毛是吸收养分和水分的重要器官，对植物耐旱性起着重要作用。本项目前期鉴定到西藏野生大麦XZ5耐旱相关根毛生长基因HvEXPB7，并对其进行了克隆及功能初步验证。在此基础上，拟开展以下研究：（1）利用HvEXPB7启动子融合GUS/GFP报告基因，研究该基因的组织定位；（2）采用转基因超表达、RNAi和BSMV-VIGS技术，分析HvEXPB7对植株根毛生长动态、离子流、离子组、光合参数及生长情况的影响；（3）研究已报道根毛生长相关基因与HvEXPB7的表达关系，筛选HvEXPB7互作基因，结合酵母双杂交和双分子荧光互补进行验证；（4）明确不同激素信号分子与HvEXPB7及其互作基因的表达关系。研究结果旨在阐明HvEXPB7调控根毛生长分子机制，揭示HvEXPB7介导的XZ5耐旱分子机理，为培育耐旱大麦品种提供新的候选基因和理论依据。

干旱是全球范围内影响植株生长、限制作物产量的最重要的非生物胁迫之一。 大麦（Hordeum vulgare L.）是世界第四大禾谷类作物，干旱胁迫正严重影响我国大麦的产量和品质。根毛是吸收养分和水分的重要器官，对植物抗旱性起着重要作用，但由于抗旱和根毛性状的复杂性，迄今在大麦上对调控这两个性状基因的研究仍比较少。本项目鉴定到西藏野生大麦抗旱相关根毛生长基因HvEXPB7，组织特异性表达和原位PCR（In situ PCR）分析发现，该基因主要在植株根部的表皮细胞中表达；生物信息学分析发现，该基因启动子区含有较多的根毛响应元件；病毒诱导基因沉默（BSMV-VIGS）研究发现，该基因沉默后的植株，根毛长度和数量显著降低，根系干物质重和根系K+浓度也显著降低；激素处理发现，乙烯能显著缓解该基因的沉默表型；大麦转基因结果显示，超表达该基因的植株，根系的生长受到了显著抑制，但根毛的生长受到了明显的促进；对野生型和超表达植株进行了转录组测序和靶向代谢组测定，用来研究该基因的调控途径。该项目研究结果不仅为大麦抗旱遗传改良提供了新的重要基因资源，而且为作物抗旱分子机理解析提供了参考。