细胞水平多组学解析根瘤调节苜蓿抗旱性的分子机制

Alfalfa (Medicago sativa L.) is a major forage crop in arid and semi-arid areas, and is of great economic and ecological significance. Drought is one of the abiotic stresses that significantly limits alfalfa production and causes a huge loss to the growers. In our previous studies, we found that root nodules can improve alfalfa performance under drought. Further analysis revealed that alfalfa plants with root nodules reduce transpirational water loss under drought by enhancing the stomatal sensitivity to ABA when compared to alfalfa plants without nodules. To understand the mechanisms how root nodules can impact stomatal behavior in alfalfa, we propose to examine molecular changes in alfalfa plants with active nodules, inactive nodules, or without nodules using an integrated multi-omics approach. We will achieve three objectives: 1) to identify genes and pathways in guard cells that are affected by nodules. This objective can be achieved by using high-throughput RNAseq to quantify transcript change in guard cells. 2) to reveal the difference in ionic responses in ABA-treated guard cells in alfalfa plants with or without nodules. This objective will be achieved by quantifying different ions using a non-invasive micro-test technology. 3) to analyze signaling molecules, including ABA, from the roots with or without nodules that may affect stomatal behavior. The objective can be achieved by examining the metabolome difference in xylem sap using LC-ESI-MS/MS and analyzing the effect of individual metabolites on stomatal closure or opening. . Through this integrated approach, we expect to have a good understanding of the molecular basis of enhanced stomatal sensitivity to ABA due to root nodule. This study will also allow us to identify novel signal molecules and mechanisms in regulating guard cell behaviors. The knowledge developed in this study will not only improve our understanding of a fundamental process in plant biology but also guide us developing novel approaches to improve alfalfa production under drought stress.

紫花苜蓿主要在干旱半干旱地区栽培，在我国草业发展中具有极重要的地位。干旱是造成苜蓿减产、经济损失的主要因素之一，调控气孔开闭、减少水分散失是植物应答干旱的重要途径。本项目主要以紫花苜蓿保卫细胞为研究对象，拟开展多组学解析根瘤提高苜蓿抗旱性的分子机制研究。在前期发现根瘤提高苜蓿抗旱性是由于增强了保卫细胞对ABA敏感性的基础上，（1）采用单细胞高通量测序技术，测定根瘤促进抗旱、保卫细胞对ABA响应的转录组差异，分析其差异基因和代谢通路。（2）以苜蓿叶片为材料，通过非损伤微测技术分析其对ABA响应差异的离子组变化。（3）通过LC-ESI-MS/MS检测叶片和伤流液的代谢物质变化，分析其代谢组变化规律。. 综合离子组、代谢组和单细胞转录组的数据，在细胞水平上阐明根瘤提高苜蓿抗旱性的代谢机制及分子调控机理，为苜蓿抗旱栽培和育种提供科学依据。

本项目开展了多组学解析根瘤提高苜蓿抗旱性的分子机制研究。在前期发现根瘤提高苜蓿抗旱性是由于增强了保卫细胞对ABA敏感性的基础上，（1）采用单细胞高通量测序技术，测定了根瘤促进抗旱、保卫细胞对ABA响应的转录组差异，分析了其差异基因和代谢通路。.（2）通过非损伤微测技术分析了相关基因的例子变化规律。.（3）通过LC-ESI-MS/MS检测叶片和伤流液的代谢物质变化，分析其代谢组变化规律，筛选了3个代谢物。. 本项目已发表论文7篇，其中SCI论文6篇。获发明专利3项。制定地方标准1个。. 项目培养博硕士研究生11人，已经培养毕业博士4人，硕士 5人，在读博士生2人。