Investigating salinity tolerance in alfalfa (Medicago sativa L.): modern synchrotron and molecular approaches

研究苜蓿 (Medicago sativa L.) 的耐盐性：现代同步加速器和分子方法

• 批准号: RGPIN-2016-06082
• 负责人: Biligetu, Bill
• 金额: $ 2.04万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=645473
• 关键词: Investigating; salinity; tolerance; alfalfa; Medicago

My long term research goal is to develop alfalfa (Medicago sativa L.) cultivars with tolerance to abiotic and biotic stresses. My short-term (5-year) objectives for this proposal are to investigate how alfalfa tolerates soil salinity at a whole plant level. I assume spatial and temporal distributions of elemental ions and organic solutes in the leaves, stems, and roots of alfalfa will vary between salt tolerant and susceptible cultivars under a salt stress. A salinity tolerant alfalfa must have a unique osmotic regulation through organic molecules or K+ and Ca2+ ions to reduce ion toxicity in the leaves. I also investigate if links exist among gene expression and biochemical changes and stress hormone's concentration in the leaves. *** To test my hypothesis, two alfalfa cultivars with contrasting tolerance to salinity will be exposed to different salt solutions and plants will be sampled periodically following salt treatments. Synchrotron radiation (SR) based phase contrast X-ray imaging, mid-infrared, soft X-ray, and X-ray Fluorescence mapping at the Canadian Light Source (Saskatoon, Canada) will be applied to quantify and localize elemental ions, organic solutes and detect their spatial and temporal distributions in alfalfa tissues. Synchrotron radiation-Fourier transform infrared (SR-FTIR) spectroscopy will be used to map changes in the ratios of carbohydrates, and α-helix to β-sheet protein secondary structures. A transcriptomic analysis of gene expression in alfalfa leaves in response to salt stress will be performed, and based on the RNA-seq analysis, and available genomic information of the model legume, Medicago truncatula, identify candidate genes to salinity tolerance in alfalfa and validate the expression of selected genes.**** Alfalfa is the most widely planted forage legume in the world. Soil salinity is a major abiotic factor that limits alfalfa production in many regions of the world. Knowledge of the biochemical composition of alfalfa tissues under salt stress is critical for the study of stress tolerance physiology, but there is a limited information available on quantification in whole plant level and spatial localization of those compounds at the tissue, cellular and subcellular levels. A comprehensive understanding of salinity tolerance in alfalfa is needed for development of novel cultivars.**** The proposed project has a goal to train Highly Qualified Personnel (HQP) including one M.Sc. student in forage stress physiology and synchrotron application, and one Ph.D. student in alfalfa genomics, two undergraduate thesis students in experimental design, statistics, plant physiology, and basic bio-technology skills. The findings will advance our understanding of the physiology and genetics of salt tolerance in alfalfa. The identification of genes will be useful for breeding new alfalfa varieties with high salinity tolerance.******

我的长期研究目标是开发能够耐受非生物和生物胁迫的苜蓿 (Medicago sativa L.) 品种。我对该提案的短期（5 年）目标是研究苜蓿如何在整个植物水平上耐受土壤盐分。我假设在盐胁迫下，苜蓿叶、茎和根中元素离子和有机溶质的空间和时间分布在耐盐品种和敏感品种之间会有所不同。耐盐苜蓿必须通过有机分子或 K+ 和 Ca2+ 离子具有独特的渗透调节，以减少叶子中的离子毒性。我还研究了基因表达和生化变化以及叶子中应激激素浓度之间是否存在联系。 *** 为了检验我的假设，将具有不同耐盐性的两种苜蓿品种暴露于不同的盐溶液中，并在盐处理后定期对植物进行取样。加拿大光源（加拿大萨斯卡通）基于同步辐射（SR）的相衬 X 射线成像、中红外、软 X 射线和 X 射线荧光测绘将用于量化和定位元素离子、有机溶质，并检测它们在苜蓿组织中的空间和时间分布。同步辐射-傅里叶变换红外（SR-FTIR）光谱将用于绘制碳水化合物以及α-螺旋与β-折叠蛋白质二级结构的比率变化。我们将对苜蓿叶片响应盐胁迫的基因表达进行转录组分析，并根据 RNA-seq 分析和模式豆科植物 Medicago truncatula 的可用基因组信息，鉴定苜蓿耐盐性的候选基因并验证所选基因的表达。**** 苜蓿是世界上种植最广泛的饲料豆科植物。土壤盐分是限制世界许多地区苜蓿生产的主要非生物因素。了解盐胁迫下苜蓿组织的生化成分对于研究耐逆性生理学至关重要，但有关全植物水平的定量以及这些化合物在组织、细胞和亚细胞水平的空间定位的信息有限。开发新品种需要对苜蓿的耐盐性有全面的了解。**** 拟议项目的目标是培养高素质人才 (HQP)，包括一名硕士学位。饲料应激生理学和同步加速器应用专业的学生，​​以及一名博士。苜蓿基因组学的学生，实验设计、统计学、植物生理学和基本生物技术技能的两篇本科论文学生。这些发现将增进我们对苜蓿耐盐生理学和遗传学的理解。基因的鉴定将有助于选育高耐盐苜蓿新品种。******