植物促生菌调控干旱胁迫下大蒜细胞膜结构与性能的作用机理研究

Garlic (Allium sativum L.), a shallow-rooted vegetable, may suffer serious drought stress during the cultivation in the dry-climate Qinghai region. In this study, special local garlic variety would be used for substrate cultivation. Garlic seedlings would be grown under drought and plant growth promoting bacteria (PGPB) treatments. To analyze changes in structure and composition of cell membrane under drought stress, integrity of cell membrane observing with a transmission electron microscope and its component content would be assayed through the isolated plasma membranes of garlic seedlings. To study the correlation between functional assessment index of cell membrane and resistance of garlic seedlings, the oxidative damage features, functional protease activities and osmotic substance content would be measured. To investigate the effect of PGPB on differentially expressed proteins under drought stress, the key protein responding to drought would be selected by iTRAQ. The mechanism of structural and functional change by PGPB would be clarified by tissue observation, physiological determination and Proteomics analysis. The research will provide theoretical basis for improving resistance and lay a foundation on high-quality and efficient production in garlic seedlings.

大蒜作为浅根蔬菜作物，在气候干燥的青海地区栽培过程中，受干旱胁迫的影响严重。本项目以青海特色大蒜品种为试材，采用基质培养，通过停止浇水进行干旱胁迫，同时施加根系促生菌悬浮液处理大蒜幼苗。分离纯化大蒜幼苗细胞膜，测定其物质组分含量，利用显微观察判断细胞膜结构完整性，分析干旱胁迫下大蒜幼苗细胞膜物质组分与结构的变化；通过分析细胞膜氧化伤害特性、特殊功能蛋白酶及渗透调节物质变化，探讨细胞膜功能评价指标与大蒜幼苗干旱胁迫抗性的相关性；利用iTRAQ蛋白组学分析技术，筛选响应干旱胁迫关键蛋白，研究干旱胁迫下根系促生菌对细胞膜差异蛋白表达及其基因功能的影响。通过结构观察、生理测定和蛋白组学分析等不同层次，阐明根系促生菌调控细胞膜结构与性能的适应性变化机制。本研究可为根系促生菌提高干旱胁迫下大蒜植株的抗性提供理论依据，对科学使用促生菌进行大蒜抗旱优质高效生产具有重要理论价值和生产实践意义。

大蒜作为浅根蔬菜作物，在气候干燥的青海地区栽培过程中，受干旱胁迫的影响严重。本项目以青海特色大蒜品种为试材，通过干旱胁迫及施加植物促生菌（PGPR）悬浮液处理大蒜幼苗。研究以细胞膜为切入点，从结构观察、生理测定和蛋白组学分析等不同层次，探究了促生菌调控干旱胁迫下细胞膜结构与性能的适应性变化机制。研究结果如下：（1）植物促生菌使干旱胁迫下大蒜的根表面积、叶片总叶绿素含量和抗氧化酶CAT、GR酶活性显著提高，根系MDA显著降低，这减少了胁迫对细胞膜的氧化伤害；（2）促生菌能够增加干旱处理下叶片组织的紧密度，减缓胁迫下细胞膜的结构损伤，降低膜组分溶血磷脂(LPC、LPE、LPG）和甘油酯（DAG）含量；（3）基于TMT蛋白组学技术共鉴定出25个细胞膜差异蛋白，促生菌主要通过上调干旱胁迫下HXK2和ADH蛋白的表达，下调ALDH7B4蛋白的表达，应答了细胞膜对干旱胁迫的响应。（4）采用TA克隆方法克隆得到细胞膜关键蛋白基因AsHXK2序列，其开放阅读框全长1500bp；通过qRT-PCR发现，不同组织中AsHXK2对根际促生菌作用下的干旱胁迫表现出不同的响应模式。干旱胁迫能够显著上调大蒜根、叶和鳞芽的AsHXK2表达水平；而在干旱胁迫施加根际促生菌的处理下，仅在叶中AsHXK2表达量显著高于干旱胁迫，表明叶片中AsHXK2对根际促生菌缓解干旱胁迫的响应较为明显。本研究初步阐明了植物促生菌缓解大蒜干旱胁迫的作用机制，为有益菌肥在大蒜抗逆高效生产的应用奠定了基础。