硝酸盐转运蛋白GbNRT2.1调节棉花抗旱的分子机理研究

Drought is one of the important factors that restrict agricultural production. The excavation of plant drought resistance related gene and the analysis of molecular mechanism in plant drought resistance have become the hotspot of abiotic stress research and molecular breeding. Cotton is an important fiber crop; yield and quality of the fiber are affected by drought. Currently, the drought resistance mechanism of cotton is seldom reported. In the previous studies, a nitrate transporter called GbNRT2.1 was isolated from RNA profiling of cotton response to biotic stress. By northern blot analysis, GbNRT2.1 were induced by many abiotic stress and hormone (PEG, NaCl, Mannitol and MeJA) treatments. Overexpression of GbNRT2.1 reduces plant resistance to drought and sensitive to ABA in Arabidopsis. Meanwhile, knock down the expression of GbNRT2.1 by VIGS enhances cotton resistance to mannitol. In this study, the drought phenotype of genetically modified cotton materials was the breakthrough point. By using physiological and biochemical analysis, the difference of the transcriptome analysis, and combining the qPCR, VIGS, BIFC, the function of GbNRT2.1 in cotton response to drought and cotton drought resistance mechanism were studied. The relationship between GbNRT2.1 mediated drought resistance and ABA signal pathway in cotton will be also studied. The function research of GbNRT2.1 will help us to elucidate the cotton drought resistance mechanism, and provide theoretical basis and genetic materials for cotton drought resistance breeding.

干旱是制约农业生产的重要因素之一，对植物抗旱基因的发掘和抗旱机理的解析是目前抗逆研究、分子育种的热点。棉花是重要的纤维作物，纤维的产量及品质都受到干旱的影响。目前关于棉花抗旱机制研究还不深入，本项目在前期研究中克隆到一个受逆境诱导的硝酸盐转运蛋白GbNRT2.1，该基因受多种逆境和激素（PEG、NaCl、甘露醇、MeJA等）诱导表达。超表达该基因会降低拟南芥对干旱的抗性，并对ABA表现出敏感性。同时在棉花中VIGS瞬时沉默该基因，干涉植株表现出更抗旱。本项目以转基因棉花材料干旱表型为切入点，通过形态结构观察、生理生化指标测定和RNA-Seq分析，结合qPCR、VIGS、BiFC等分子手段对GbNRT2.1在棉花抗旱中的功能及作用机理进行研究。探讨该基因介导的干旱调节与ABA信号路径之间的关系，其在棉花干旱响应中的功能研究将有助于阐明棉花抗旱机制，并为棉花抗旱育种提供理论基础和遗传材料。

干旱是制约农业生产的重要因素之一，对植物抗旱基因的发掘和抗旱机理的解析是目前抗逆研究、分子育种的热点。棉花是重要的纤维作物，纤维的产量及品质都受到干旱的影响。目前关于棉花抗旱机制研究还不深入，本项目在前期研究中克隆到一个受逆境胁迫和激素处理诱导表达的硝酸盐转运蛋白GbNRT2.1。该基因在不同发育时期表现出不同的组织表达模式。超表达GbNRT2.1降低了拟南芥和棉花对干旱的耐受性，而沉默和突变GbNRT2.1的植株表现出更耐旱的表型。内源激素测定和转录组分析结果显示，GbNRT2.1对植物耐旱性的调控可能与衰老进程的诱导相关。干旱处理后，超表达棉花材料中植物衰老相关基因的表达丰度显著高于野生型，而沉默和突变材料低于野生型。离体叶片的暗诱导实验验证了这一结论，GbNRT2.1超表达拟南芥叶片在暗培养下衰老速度显著加快，衰老相关标志基因在超表达材料中显著上调。说明GbNRT2.1调控了植物衰老过程，GbNRT2.1增强植物对干旱胁迫敏感性可能是由于胁迫条件下更快衰老造成的。NRT2.1可能参与响应外界环境变化，调控植物对于不利环境的适应过程。本研究可以为硝酸盐转运蛋白的功能研究提供新的思路。在棉花中干涉GbNRT2.1基因增强了棉花的耐旱性，可作为棉花耐旱育种的候选基因。本研究在棉花中敲除GbNRT2.1基因获得了不含T-DNA片段的突变体材料，可作为耐旱育种的种质资源。