江西东乡野生稻渗入系耐旱新基因OsDT1的功能鉴定

Drought stress is one of the most important factors which affect and limit crop production, so identification of plant drought tolerant genes have important significance for cultivating drought tolerant varieties and revealing molecular mechanisms of drought tolerance in plants..In previous study, a drought tolerant introgression line, IL23, was identified from a set of introgression lines, derived from a cross between Dongxiang Common wild rice (Oryza rufipogon Griff.) and an Indica cultivar Guichao 2 (Oryza sativa L.), and the drought tolerance of IL23 was obviously superior to its recurrent parent Guichao 2. Combined with gene chip hybridization results, a new drought tolerant gene OsDT1 located in QTL region was candidate which was derived from the Dongxiang wild rice..In this project, the over-expression vector and RNAi vector of OsDT1 would be constructed for rice genetic transformation, and the drought tolerance of transgenic plants would be analyzed. The proteins interacted with OsDT1would be screened by yeast two-hybrid system, and the expression profile of the downstream genes of OsDT1 would be investigated by rice whole genome microarray, in order to identify the signaling pathways which OsDT1 may be involved in..Synthesizing the above research results, a comprehensive understanding of the new gene OsDT1 could be obtained about drought tolerance, which could be used for breeding drought tolerant rice varieties, and providing important reference to reveal the plant drought tolerant molecular mechanisms.

干旱胁迫是影响和限制农作物生产的主要逆境因素之一，鉴定植物耐旱基因的功能对培育耐旱品种、揭示植物耐旱分子机理具有重要意义。我们以桂朝2号为遗传背景的江西东乡野生稻野栽渗入系为材料，筛选出一个耐旱系IL23，其耐旱性明显优于轮回亲本桂朝2号。结合基因芯片杂交结果，从QTL定位区域筛选出1个源于东乡野生稻的耐旱新基因OsDT1。本项目将在此基础上，构建OsDT1的过表达载体和RNAi载体，进行水稻遗传转化，分析转基因植株的耐旱性；采用酵母双杂交技术分析该基因的互作蛋白；利用水稻全基因组芯片分析OsDT1下游基因的表达变化，探讨该基因可能参与的信号通路。通过以上对耐旱新基因OsDT1的研究，可以对其在提高水稻耐旱性方面的功能有一个较为全面的认识，以期为培育耐旱水稻品种提供新基因，也为揭示植物耐旱分子机制提供重要参考。

在前期工作中，我们从桂朝2号为遗传背景的江西东乡普通野生稻渗入系群体中，筛选到了一个苗期稳定的耐旱渗入系IL23，在它的耐旱QTL区域中筛选到1个与苗期耐旱性相关的新基因（OsDT1）。该基因作为表达蛋白来源于野生稻，它的渗入能使IL23的F2:3家系群体的耐旱性提高24.2%，本项目对该基因的功能开展了研究：1，采用RACE技术得到耐旱新基因OsDT1的全长序列，其编码的蛋白可能是跨膜蛋白，并存在新的结构域；2，OsDT1的表达受PEG、ABA和NaCl胁迫的诱导，而低温处理会抑制其表达，该基因存在组织特异性表达特性，在生殖组织（小穗等）表达量较高；3，OsDT1的过表达转基因植株在水培PEG胁迫处理和盆栽自然干旱条件下，与对照相比耐旱性都有所增强，失水率、渗透势和红外热图分析表明，在PEG胁迫下转基因株系能及时关闭气孔、减少蒸腾，从而减少水分丧失，更好的维持细胞膨压，维持生长；4，大田考种结果表明，过表达转基因株系S12-7等多个株系表现出增产优势。综合以上研究内容，我们认为OsDT1基因对提高水稻耐旱性有重要意义。