醛脱氢酶基因ScALDH21介导的棉花黄萎病抗性机制解析

Plant molecular breeding is the new way to resistance breeding of cotton Verticillium wilt. Cotton Verticillium wilt is the main diseases affecting cotton production in China, its pathogenic bacteria is Verticillium dahliae. However, the difficult prevention and control of cotton verticillium wilt, disease-resistant breeding lag, especially that very difficult in Gossypium hirsutum. Based on the early stage of the project team, we have breed transgenic aldehyde dehydrogenase gene (ScALDH21) Gossypium hirsutum (TC)，whose gene is from Syntrichia caninervis. The TC cotton has significant verticillium wilt resistance. Especially under the water stress condition, verticillium wilt incidence of TC was less than NT (non-transgenic cotton). This project intends to: (1) Analysis the soil microbial population dynamics around the cotton root and Verticillium dahliae pathogenicity; (2) identify plant metabolism and transcriptional regulation difference, under withholding water and water sufficient condition. The result will show lights on adjustment function of transgenic ScALDH21 cotton in soil microbial ecological, and on metabolic and transcriptional regulation pathways of transgenic ScALDH21 cotton. In addition, clarity the verticillium wilt disease-resistant mechanism of transgenic ScALDH21 cotton, and will help to provide new cotton germplasm for polymerization genetic breeding.

植物分子育种为棉花抗病育种提供新途径。棉花黄萎病是影响我国棉花生产的主要病害，其致病菌为大丽轮枝菌(Verticillium dahliae)。由于棉花黄萎病防治难度大，抗病育种滞后，尤其是在陆地棉(Gossypium hirsutum)中筛选抗病品种非常困难。课题组前期培育的转齿肋赤藓醛脱氢酶基因(ScALDH21)陆地棉具有显著的黄萎病抗性，尤其在水分匮缺条件下，与野生型棉花比较，其对黄萎病达到高抗水平。本项目拟在水分胁迫和水分充足两种条件下，通过分析棉花根周土壤微生物的种群动态，大丽轮枝菌侵染率、并从代谢水平及基因表达调控水平，阐明转ScALDH21棉花对根周土壤微生物的调节功能，抗病代谢通路以及基因转录表达抗病调控机制，从而揭示ScALDH21基因对棉花黄萎病的抗病作用机制，为我国棉花黄萎病抗病育种提供理论依据和新种质。

植物分子育种为棉花抗病育种提供新途径。棉花黄萎病是影响我国棉花生产的主要病害，其致病菌为大丽轮枝菌(Verticillium dahliae)。本项目通过连续黄萎病情调查，大田试验证明转ScALDH21基因棉花具有稳定的黄萎病抗性；从发病等级和黄萎病病情指数都优于受体对照。统计产量结果表明，转基因株系在黄萎病情况下平均增产36.6%。通过生理和代谢组分析揭示转ScALDH21棉花具有更为强大的生理代谢防线。主要增加了大环内酯类（合成抗生素的中间物）、抗生素和莽草酸途径的生物碱的生物合成，促进抗菌性。进一步从基因转录水平揭示转基因棉花黄萎病抗性提高的内在调节机理：GO富集分析显示转基因株系中ROS清除相关酶类基因、细胞壁相关基因、病原菌降解相关酶类基因和蛋白质泛素化相关基因等上调表达；KEGG分析显示植物激素信号转导、谷胱甘肽代谢、植物MAPK信号传导和植物与病原菌互作途径这四条植物抗病相关代谢途径显现出最高的显著性，最终增强对病原菌的降解、自身防御结构的加强、氧化物质的清除、抗性次生代谢产物等来抵御大丽轮枝菌的胁迫。本项目揭示ScALDH21基因对棉花黄萎病的抗病作用机制，为我国棉花黄萎病抗病育种提供理论依据和新种质。. 同时，土壤微生物分析表明：与非转基因棉花相比，经过一个生育期的种植，转基因棉花种植区土壤理化性质未发生显著改变，反映微生物群落变化的Alpha多样性指数，Beta多样性指数均未发生显著改变，环境因子关联分析表明三组样本并未表现出对环境因子的依赖性。最终解释转基因棉花并未对土壤微生物群落和土壤理化性质造成显著影响，表明转ScALDH21棉花环境安全性较高，适用于大规模种植。. 因此，极端耐旱的齿肋赤藓ScALDH21基因是潜在优异的抗逆基因资源，该转基因棉花有望育成黄萎病抗性品种。该基因为高等开花植物丢失基因，有望提高其他作物抗逆性。