沙生灌木白刺耐盐机理的解析及耐盐基因资源的开发

The mechanism of that saline plants adapt to salt-stress environment, involves in complex factors, such as cell structure, physiological processes and metabolism regulation. Among these complicated processes, Na+/H+ antiporters play an important role in plant salt-tolerance. Na+/H+ antiporters are integral proteins embeded in vacuolar membrane and cytomembrane. The cytomembrane Na+/H+ antiporter proteins can transport cytoplasmic Na+ to the exocellular, and the vacuolar Na+/H+ antiporter proteins can deliver Na+ into the vacuoles against the electrochemical gradient. The compartmentation of Na+ provides an effective mechanism to avert the deleterious effects of Na+ on cytosol, and maintain an osmotic potential by Na+ in vacuoles. . Nitraria L. is a genus of flowering plants in Zygophyllaceae family, which grows primarily in deserts and semideserts, and exhibits strong salt-resistance. Therefore, the research on molecular mechanism of salt-tolerance in Nitraria is very necessary. In the project, our objective is to elucidate salt-tolerance mechanism and exploit salt-tolerance related genes of Nitraria L. We plan to isolate orthologs of NHX and SOS genes that encoded vacuolar and cytomembrane Na+/H+ antiporters, respectively, from Nitraria L., and analyze their salt-tolerance mechanism by investigating expression pattern of the two genes and ion subcellular location under salt-stress conditions. On the other hand, for analyzing application of the two genes in salt-tolerance improvement of plants, we plan to transfer the two genes into Arabidoposis thaliana and Populus tomentosa, and investigate traits of the transgenic plants. The research will provide theoretical and experimental bases for improving salt tolerance of forage grass, agricultural crops and forest trees through genetic transformation with salt-tolerance related genes of the important saline plants.

盐生植物适应高盐环境涉及复杂的细胞结构、生理过程和代谢调控机制，其中Na+/H+逆向转运蛋白扮演至关重要的角色。Na+/H+逆向转运蛋白分布在细胞质膜和液泡膜上，液泡膜上的Na+/H+逆向转运蛋白（NHX）将细胞中的Na+逆着Na+浓度梯度运送到液泡中区隔化集中，质膜上的Na+/H+逆向转运蛋白（SOS）将细胞质中的Na+逆向运送到胞外高Na+环境中，以减少钠离子对细胞器的毒害并维持细胞的渗透平衡。白刺是内蒙地区的自然植物区系盐生植物，其自然抗逆性突出，是干旱盐碱地带植物群落的建群种。因此，研究白刺的耐盐分子机理、开发其耐盐基因资源具有重要意义。本申请项目拟分离白刺的NHX和SOS基因，通过对这两个基因在盐胁迫下的表达特性及离子亚细胞定位分析，探明白刺的耐盐机理，并通过转基因等方法分析这两个基因在甜土植物中的表达，为今后利用该基因进行牧草、农作物和林木的耐盐性遗传改良提供理论和实验依据。

盐生植物适应高盐环境涉及复杂的细胞结构、生理过程和代谢调控机制，其中离子转运蛋白扮演至关重要的角色。Na+/H+逆向转运蛋白分布在细胞质膜和液泡膜上，液泡膜上的Na+/H+逆向转运蛋白（NHX）将细胞中的Na+逆着Na+浓度梯度运送到液泡中区隔化集中，质膜上的Na+/H+逆向转运蛋白（SOS）将细胞质中的Na+逆向运送到胞外高Na+环境中，以减少钠离子对细胞器的毒害并维持细胞的渗透平衡。另一方面，位于质膜上的高亲和钾离子转运蛋白（HKT1）能够将茎木质部中过多的Na+经共质体途径卸载到韧皮部，再运输回根部，以防止地上部分Na+积累过多。白刺是内蒙地区的自然植物区系盐生植物，其自然抗逆性突出，是干旱盐碱地带植物群落的建群种。因此，研究白刺的耐盐分子机理、开发其耐盐基因资源具有重要意义。.本研究利用同源克隆技术分离了西伯利亚白刺的NHX、SOS和HKT1基因，并对其编码的蛋白质的分子特征、在盐胁迫下的表达特性进行了分析。结果显示，NsNHX1、NsSOS1和NsHKT1均具备离子转运蛋白的分子特征，其表达均受低温、干旱和高盐等非生物胁迫的诱导。另外，通过遗传转化拟南芥和毛白杨的方法调查了目的基因的功能及其在植物耐盐性遗传改良中的应用价值。这些结果显示，NsNHX1、NsSOS1和NsHKT1的过量表达不同程度地提高转基因植物的耐盐性，表明NsNHX1、NsSOS1和NsHKT1在西伯利亚白刺适应高盐环境中发挥重要作用，它们可作为重要的候选基因应用于牧草、农作物和林木的耐盐性遗传改良。