阿拉善荒漠区特有植物长叶红砂盐腺泌盐特性及相关分子机理研究

Soil salinity is the major environmental factor limiting plant growth and productivity. Plant genetic engineering is recognized as an important way in improving the capacity of plant salt tolerance, developing and utilizing salinization land. Studying the salt-resistant mechanism and screening related genes of halophytes is the premise to do such jobs. Reaumuria trigyna is an endangerd small shrub native to the Eastern Alxa-Western Ordos area. This dicotyledonous recretohalophyte has superior ability to tolerate the stress imposed by saline soil environment. Since the transcriptome sequencing of R. trigyna was done, it could be considered as a reference species of recrehalophytes with detailed genomic information. According to our previous studies, ion excretion of R. trigyna via the multicellular salt glands plays vital role in its response to salinity, but little is known about the mechanisms underlying the unique adaption strategy. Based on the tanscriptome sequencing data, this project will 1) precisely separate and collect the salt glands of R. trigyna by using laser capture microdissection technology; 2) identify the unigenes associated with ion transport and vesicular transport in salt glands through hybridization with the small-scale microarray; 3) select 2-3 genes closely related to salt secretion, and transform them into Arabidopsis genome to analyze their functions; 4)investigate the net ion fluxes of individual salt gland in the leaves of R. trigyna under different treatments, such as plant hormone and stress signal molecule. The research conducted above will laid a foundation for further improvement and clarification of the salt-secreted mechanisms in this species and other recretohalophytes and will provide theoretical and practical proof for exploration of the excellent stress-resistant genes of R. trigyna.

土地盐渍化是限制植物生长的主要环境因子，研究盐生植物耐盐机理、筛选高效耐盐基因应用于甜土植物改良，是治理和利用盐渍化土地的重要途径。长叶红砂为阿拉善荒漠区特有的珍稀泌盐植物，对盐渍环境具有极强的适应性，目前已完成耐盐转录组深度测序，可作为盐生植物研究的代表物种。前期研究表明，盐腺泌盐在该植物适应高盐生境中发挥着至关重要的作用，但对其如何参与耐盐响应的内在机制尚不清楚。本项目通过激光捕获显微切割法富集长叶红砂的盐腺细胞，基于长叶红砂耐盐转录组数据，定制小规模基因芯片，确定在参与盐腺泌盐的离子转运和膜泡运输相关基因，从中挑选表达量差异显著的2-3个基因，在拟南芥中进行过量表达和功能鉴定；同时，通过非损伤微测技术对盐腺细胞泌盐的离子选择性及影响因素进行系统研究。实验结果将为完善并阐明长叶红砂盐腺的泌盐特征和调控机理，了解泌盐盐生植物的耐盐机制，开发利用该植物优异抗逆基因资源提供理论和实践依据。

土地盐渍化是限制植物生长的主要环境因子，研究盐生植物耐盐机理、筛选高效耐盐基因应用于甜土植物改良，是治理和利用盐渍化土地的重要途径。本项目以阿拉善荒漠区特有泌盐植物长叶红砂为研究对象，基于耐盐转录组数据，定制小规模基因芯片，确定了多个参与盐腺分泌的离子转运、膜泡运输及转录调控相关基因，并从中筛选2条优质基因，通过转化拟南芥验证其功能；同时，系统探讨在盐胁迫条件下，离子转运或膜泡运输抑制剂、胁迫信使、盐浓度等对长叶红砂盐腺细胞泌盐及耐盐性的影响，为完善并阐明长叶红砂盐腺的泌盐特征和调控机理，应用其进行植物耐盐性遗传改良奠定基础。结果显示：1. 在芯片检测的2776条基因中，131条基因差异表达，其中51条基因上调表达，80条基因下调表达。在这些差异表达基因中，发现13条膜泡运输相关基因、18条离子转运相关基因、23条物质代谢相关基因及77条转录因子和激酶。2. 膜泡运输抑制剂BFA、H+-ATPase专一抑制剂钒酸钠、Na+/H+逆向转运蛋白抑制剂阿米洛利和Na+：K+：Cl-共转运体抑制剂布美他尼均可以显著降低长叶红砂单个盐腺分泌Na+、K+的能力，提示膜泡运输和离子转运基因可能参与长叶红砂的泌盐过程。3. NO和Ca2+可以通过提升长叶红砂单个盐腺的泌盐能力，增强抗氧化系统活性，减少有害物质的积累，降低细胞质膜损伤程度，最终提高植株在盐渍环境中的生存能力。4. RtMYB1和RtVAMP基因在盐及其他胁迫条件下均上调表达，可能在长叶红砂适应严酷生境方面发挥重要作用。目前，已成功转化拟南芥，抗逆功能分析工作正在进行中。