星星草-丛枝菌根共生体应答盐碱逆境的生理机制解析

Arbuscular mycorrhizal fungi can improve the salt tolerance of plants. Puccinellia tenuiflora is an excellent plant in the improvement of the salt-alkali grassland, and has extremely strong tolerance to salt-alkali stress which is closely related to the arbuscular mycorrhizal fungi, because that Puccinellia tenuiflora response to salt-alkali stress in the form of "Puccinellia tenuiflora-arbuscular mycorrhizal symbiont". while it is not clear yet on the salt-alkali tolerant physiological mechanism of this symbiont. In this project, two kinds of dominant arbuscular mycorrhizal fungi isolated from the rhizosphere of Puccinellia tenuiflora in Songnen grassland and identified in our previous study, will be inoculated with the seedlings of Puccinellia tenuiflora under the simulated salt-alkali stress conditions, and then proteomics and metabolomics which is very hot now in the systematic biological research, will be applied to investigate the physiological and metabolic characteristics in relation to the salt-alkali tolerance of Puccinellia tenuiflora-arbuscular mycorrhizal symbiont on the whole, which can be a good complementary to the deficiency of only partly focusing on few physiological indicators, in order to deeply reveal the response mechanism of Puccinellia tenuiflora-arbuscular mycorrhizal symbiont to salt-alkali stress on the physiological level.The results of this study can not only supply a scientific basis for the use of mycorrhizal technology to further enhance the salt tolerance of Puccinellia tenuiflora as well as the bioremediation and reestablishment of the degraded salt-alkali Songnen grassland, but also lay an important foundation on the screening of the saline-alkali stress related genes, and the further research on the function of these genes using genetic methods.

丛枝菌根真菌能够提高植物的耐盐能力。星星草(Puccinellia tenuiflora)是改良盐碱草地的优质牧草，具有极强的耐盐碱能力，这与丛枝菌根真菌有着密切的关系，因为星星草是以“星星草-丛枝菌根共生体”的形式协同应答盐碱逆境的，但是关于该共生体的耐盐碱生理机制还并不明确。本项目以前期研究中从松嫩盐碱草地星星草根围分离并鉴定出的两种优势丛枝菌根真菌接种星星草幼苗，人工模拟盐碱胁迫条件，应用系统生物学研究中较为热点的蛋白质组学与代谢组学技术从“整体”上分析星星草-丛枝菌根共生体的耐盐碱相关生理与代谢特征，有力地弥补了以往研究仅“局部”考察少数生理指标的不足，在生理学水平上深入揭示星星草-丛枝菌根共生体应答盐碱逆境的机制，为利用菌根技术进一步提高星星草的耐盐力，改良与恢复退化松嫩盐碱草地提供科学依据，还可为筛选盐碱胁迫相关基因，进而利用遗传手段深入研究这些基因的功能奠定重要基础。

为探究“星星草-丛枝菌根共生体”的耐盐碱生理机制，以根内根生囊霉接种星星草幼苗，人工模拟盐碱胁迫条件，在研究了星星草幼苗AM真菌侵染特性及耐盐碱生理特性的基础上，应用蛋白质组学与代谢组学技术从“整体”上分析了“星星草-丛枝菌根共生体”的耐盐碱相关生理与代谢特征。研究结果表明，盐碱胁迫下接种AM真菌的星星草根部侵染指标有所降低，但泡囊丰度却有所提升；AM真菌促进了盐碱胁迫下星星草叶绿素和可溶性糖含量的增加，提高了星星草体内抗氧化酶的活性；促进了星星草体内的K+以及Ca2+的积累而降低了Na+的积累，有效维持了星星草体内的离子平衡；200mM的NaHCO3胁迫下，在星星草体内共鉴定出598个显著差异表达蛋白，涉及活性氧代谢、苯丙烷类生物合成、碳水化合物和能量代谢、翻译、硫代谢、光合作用、氮代谢和氨基酸代谢等过程；200mM的NaHCO3胁迫下，星星草体内氢吗啡酮上调21.38倍，乙基吗啡上调20.02倍，槲皮素3'-甲基醚上调16.67倍，芹菜素7-O-新橙皮苷下调12.5倍。本研究的结果可为筛选耐盐碱胁迫相关基因，进而利用遗传手段深入研究这些基因的功能奠定重要基础。