塔里木盆地荒漠区驼蹄瓣属植物的耐盐特性与耐盐基因挖掘

The Tarim Basin is the most serious soil salinization region in Xinjiang area, planting salt tolerant plants is an important measure to improve the situation. Zygophyllum L. plants as typical halophyte in Tarim Basin resistant to extreme salt-stressed environment, the preliminary study found that responses to salt stress of species in the genus were obviously different. The project study with salt tolerance species Z.rosovii and salt sensitive species Z.fabago, through the microscope and scanning electron microscope observation of tissue sections and ultrathin sections of seedlings roots and blade, to elucidate the morphological strain mechanism under salt stress of two Zygophyllum L. species in cell and subcellular level; By metabolomics’ and physiological testing methods, through the analysis of difference small metabolites before and after salt stress, as well as the changes of Na+ and K+ content, and activities of the antioxidant enzyme system, to clarify the physiological mechanism of two plants adapt to the salt stress; by RNA-seq technology, acquired the genes related to salt tolerance, and clone the differently expressed genes and verify their function, which provide a theoretical basis for the mining of salt tolerance genes in plant resources in Tarim Basin. The results of this research have vast importance to the salt tolerance elucidation of Zygophyllum L. plants under extreme salt-stress, and exploitation and utilization of excellent plant resources for saline soil improvement.

塔里木盆地是新疆土壤盐渍化最严重的地区，种植耐盐植物是有效改良现状的重要措施。驼蹄瓣属植物作为塔里木盆地典型盐生植物可耐极端盐环境，前期研究发现该属内不同种间植物响应盐胁迫的方式明显不同。本项目以耐盐的石生驼蹄瓣（Z.rosovii）和对盐敏感的驼蹄瓣（Z.fabago）为研究对象，通过幼苗根、叶的组织切片及超薄切片的显微镜和扫描电镜观察，从细胞、亚细胞水平阐明两种驼蹄瓣属植物在盐胁迫下的形态、结构胁变机制；运用代谢组学及生理检测方法，通过两种驼蹄瓣属植物盐胁迫前后小分子代谢产物的差异分析，以及Na+、K+含量和抗氧化酶系统活性的变化，阐明两种植物适应盐胁迫的生理机制；通过RNA-seq技术获得耐盐相关基因，并对差异表达基因进行克隆及功能验证，为塔里木盆地植物资源耐盐基因的挖掘提供理论依据。研究结果对该属植物极端盐环境下耐盐特性的阐明以及盐碱地改良中优异植物资源的开发利用均具有重要意义。

土壤的盐渍化问题一直是一个备受关注的世界性难题，为挖掘出广泛存在于塔里木盆地的驼蹄瓣属植物的耐盐基因，本研究以三种野外采集的驼蹄瓣属植物为实验材料，通过盐胁迫处理幼苗实验，筛选出耐盐的Z.brachypterum与盐敏感的Z.fabago两个种。细胞学分析表明，耐盐的Z.brachypterum茎与叶片均比盐敏感的Z.fabago厚。盐胁迫处理后Z.brachypterum叶片中开放的气孔比率也较Z.fabago低，且随着盐处理浓度的增加，Z.brachypterum叶片中CAT、SOD、POD、脯氨酸及叶绿素积累量要高于Z.fabago。继而通过转录组与代谢组学关联分析，发现了2个支链氨基酸转移酶（branched-chain-amino-acid aminotransferase，BCAT）基因参与的泛酸盐与辅酶A（CoA）代谢途径可能影响驼蹄瓣属的耐盐性。进一步分析发现这两个BCAT基因序列高度一致，3’端仅部分序列不一致，推测可能是同一基因的不同剪接所致。我们构建了ZfBCAT1基因的超表达载体，分别转化拟南芥与水稻，获得了该基因过表达的纯合株系，初步结果发现在水稻中异源表达ZfBCAT1基因显著降低了水稻的盐抗性。这些结果将为解析植物的耐盐性调控网络提供一个新思路，也将为塔里木盆地植物耐盐相关基因的挖掘提供理论依据和基因资源。