N-乙酰基高丝氨酸内酯对植物耐盐性的影响及机制分析

Improving salinity tolerance of crop plants has been an important aim of modern agricultural development. With the development of biological control, people pay more and more attention to Gram-negative bacteria Serratia plymuthica, which can be used as biocontrol agent against most of fungi pathogens. An endophytic strain G3 of Serratia plymuthica used in this study was isolated from the stems of wheat. Our previous studies demonstrated that N-acylhomoserine lactones (AHLs)-mediated quorum-sensing (QS) systems in G3 positively regulated proteolytic and chitinolytic activities, antibiotic pyrrolnitrin production and biofilm formation. It was also found that lower concentration of AHL has relieving effect on Arabidopsis or rice seedlings under NaCl stress. To better elaborate the molecular mechanism of promoting plant growth and anti-adversity by AHL, we employed proteomic approach to investigate the influence and mechanism of AHL quenching on salt tolerance and growth of Arabidopsis thaliana under salt stress. Proteome of Arabidopsis thaliana seedlings with AHL standard sample treatment was used as a positive control. Differentially expressed proteins and their corresponding signal/metabolic pathways were identified. Moreover, the physiological and biochemical functions of marker genes for key pathways as well as their regulators were further characterized. Based on these studies, we try to provide some theory basis for improving plant growth and salt tolerance through AHL manipulation.

提高作物的耐盐性是现代农业发展的重要目标之一。Serratia plymuthica菌株G3是分离自小麦内茎的内生细菌，具有抗病和促生潜能。前期研究结果表明G3利用N-乙酰基高丝氨酸内酯(AHLs)介导的群体感应(QS)系统正调控蛋白酶和几丁质酶活性，抗生素硝吡咯菌素的产生和生物膜形成等，并且低浓度的AHL可以缓解 NaCl对拟南芥及水稻幼苗生长的胁迫作用。为了更好地理解AHL参与调控植物促生及抗逆的机制，我们侧重应用蛋白质组学技术解析盐胁迫下AHL信号淬灭对拟南芥耐盐性和生长发育的影响及作用机理，并以化学合成的AHL标准样品处理为阳性对照检测拟南芥对AHL的响应。鉴定与耐盐性相关的差异蛋白及其参与的信号通路；并对关键信号途径中的标志基因及其调控因子进行生理生化功能鉴定。旨在为通过操纵AHL信号改善植物生长和抗逆性提供理论依据。

提高作物的耐盐性是现代农业发展的重要目标之一。Serratia plymuthica菌株G3是分离自小麦内茎的内生细菌，具有抗病和促生潜能。表型分析结果表明盐胁迫抑制了植物的生长参数，提高了抗氧化系统酶如超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性。低浓度的N-乙酰基高丝氨酸内酯（AHL）可以缓解 NaCl对拟南芥及水稻幼苗生长的胁迫作用，显著提高生长参数及SOD和POD的活性。G3及其AHL突变体均可以提高水稻及拟南芥幼苗对盐胁迫的耐受性。为了更好地理解AHL参与调控植物促生及抗逆的机制，我们侧重应用蛋白质组学技术分析了拟南芥幼苗经NaCl, AHL, NaCl+AHL，NaCl+G3/6000，及NaCl+G3/6863处理后蛋白表达谱的变化，共鉴定到97个至少在一种处理中表达发生1.5倍变化的蛋白质。质谱分析和功能注释表明这些蛋白参与多种代谢和调控途径，包括防卫胁迫反应/脱毒，光合作用，蛋白质代谢，碳水化合物代谢，氨基酸代谢及能量等。这些结果表明防卫反应的增强，光合效率的提高，细胞壁的修饰及各种代谢物的平衡可能对于AHL调控的改善植物生长及提高抗逆性有重要作用。本研究在为通过操纵AHL信号改善植物生长和抗逆性提供了一些理论依据。