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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709900
• 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 -helix to -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紫花苜蓿(Medicago sativa L.)耐非生物和生物胁迫的品种。我这项提议的短期(5年)目标是调查紫花苜蓿在整个植物水平上如何耐受土壤盐分。我认为在盐胁迫下，耐盐和敏感品种紫花苜蓿叶、茎和根中元素离子和有机溶质的时空分布会有所不同。耐盐性紫花苜蓿必须通过有机分子或K+、Ca~(2+)离子进行独特的渗透调节，以减少叶片中的离子毒害。我还研究了叶片中的基因表达和生化变化与胁迫激素浓度之间是否存在联系。 为了验证我的假设，两个对盐分耐受性不同的紫花苜蓿品种将被暴露在不同的盐溶液中，并在盐处理后定期对植物进行采样。基于同步辐射(SR)的相位对比X射线成像、中红外、软X射线和加拿大光源(加拿大萨斯卡通)的X射线荧光成像将被用于量化和定位元素离子、有机溶质，并检测它们在紫花苜蓿组织中的时空分布。同步辐射傅里叶变换红外光谱(SR-FTIR)将被用来绘制碳水化合物和螺旋与片状蛋白质二级结构比率的变化图。本研究将对紫花苜蓿叶片对盐胁迫响应的基因表达进行转录转录分析，并基于RNA-seq分析和模式豆科牧草紫花苜蓿的基因组信息，筛选出紫花苜蓿耐盐的候选基因，并验证所选基因的表达。 紫花苜蓿是世界上种植最广泛的豆科牧草。土壤盐分是限制世界许多地区紫花苜蓿产量的主要非生物因素。了解盐胁迫下紫花苜蓿组织的生化组成对于研究耐盐生理是至关重要的，但关于这些化合物在整个植物水平上的量化以及这些化合物在组织、细胞和亚细胞水平上的空间定位方面的信息有限。培育新品种需要对紫花苜蓿耐盐性的全面了解。 拟议项目的目标是培养高素质人才(HQP)，包括一名理科硕士。一名学生攻读饲料胁迫生理学和同步加速器应用，一名博士生攻读紫花苜蓿基因组学，两名本科生攻读实验设计、统计学、植物生理学和基本生物技术技能。这些发现将促进我们对紫花苜蓿耐盐性的生理和遗传学的理解。这些基因的鉴定将有助于培育高耐盐性的紫花苜蓿新品种。