根际细菌增强翅碱蓬抗逆能力的分子机制研究

Protection and remediation of the heavily polluted coastal wetland is an important constituent of the blue carbon sink development in China. The pioneer plant Suaeda heteroptera functions to comprehensively restore the damaged ecosystem of salt marshes, which makes it a most promising plant in the bioremediation of polluted coastal wetland. Due to the ever-increasing salinization of wetland and disturbance of anthropogenic activities, the Suaeda communities which used to thrive in the wetland of Shuangtaizi Estuary in Liaodong Gulf have been degenerating since 2000. Increasing the capacity of stress resistance in Suaeda is an effective way to check the degeneration and restore the vegetation. Plant growth promoting rhizobacteria (PGPR) is capable of enhancing the universal stress resistance of plants through priming their immune system, which is called “Induced System Resistance” (ISR). Revealing the mechanisms underlying ISR is critical for ensuring the stable efficiency of phytoremediation. In this study, we plan to work on the “Suaeda heteroptera-rhizospheric microorganisms” system and isolate PGPR which could universally enhance the stress resistance of Suaeda heteroptera. The molecular mechanisms of PGPR-induced “systemic resistance” are investigated using comparative transcriptomics. Additionally, field experiments are performed to examine the growth and development of PGPR-inoculated Suaeda heteroptera exposed to natural stresses. Our study is of great interest to direct the designing of plausible bioremediation strategies to protect and restore polluted coastal wetland.

保护和修复受污染滨海湿地是发展我国蓝色碳汇的重要内容。“先锋植物”翅碱蓬对盐碱土壤有综合改良作用，是修复受污染滨海湿地的重要植物物种。受土壤盐渍化、过度开发等因素影响，辽东湾双台子河口的翅碱蓬滨海湿地近年来退化严重，翅碱蓬大片枯死。提高翅碱蓬自身抗逆能力是恢复翅碱蓬群落的有效办法。根际促生菌能够通过“启动”植物免疫防御机制来增强植物应对多重环境胁迫的能力，即诱导植物产生“系统抗性”。对这一“诱导型系统抗性”分子机理的解析是实施高效、稳定的植物修复的前提和保证。本研究拟以“翅碱蓬-根际细菌”为研究对象，从翅碱蓬根际分离能够提高翅碱蓬综合抗逆能力的促生菌，通过比较全转录组学方法研究翅碱蓬产生“诱导型系统抗性”的机理，并进行野外实验检验自然环境中根际促生菌作用下的翅碱蓬生长发育状况。本研究的开展对制定切实可行的受损滨海湿地生物修复策略有重要的指导意义。

本项目建立了水培翅碱蓬高盐胁迫模型，利用比较转录组学方法研究了翅碱蓬响应高盐胁迫的分子机制，共获得了144个差异表达基因，对差异表达基因进行GO富集分析和KEGG富集分析，明确了差异表达基因富集的分子功能与代谢途径，研究结果可望为更深入研究翅碱蓬耐盐分子机制提供理论基础。本项目还从翅碱蓬根际分离获得逾千株细菌的纯培养，根据16S rDNA的限制性片段长度多态性将其分为33组，对每组根际细菌的16S rDNA全长测序并对序列进行BLAST比对，鉴定出包括Bacillus、 Enterobacter、Klebsiella、Stenotrophomona、Pantoea、Pseudomonas等在内的13属不同种细菌；通过选择性平板培养法筛选出20余株至少具备固氮、溶磷、解钾性能之一的翅碱蓬根际细菌，并从中筛选出2株在实验室条件下和野外实地都能显著提高翅碱蓬发芽率的翅碱蓬根际促生菌，1株为Klebsiella aerogenes，1株为Enterobacter cloacae。分离获得的翅碱蓬根际细菌扩充了翅碱蓬促生菌的资源库，在植物促生方面有较好的应用前景。