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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682490
• 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培育紫花苜蓿（Medicago sativa L.）对非生物和生物胁迫具有耐受性的品种。我的短期（5年）的目标，这个建议是调查如何苜蓿容忍土壤盐分在整个植物水平。我认为在盐胁迫下，苜蓿的叶、茎和根中元素离子和有机溶质的时空分布在耐盐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Ca 2+离子进行独特的渗透调节，以降低叶片中的离子毒性。同时也探讨了叶片中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，两个苜蓿品种与对比耐盐性将暴露于不同的盐溶液和植物将定期取样后盐处理。基于同步辐射（SR）的相位衬度X射线成像，中红外，软X射线，和X射线荧光映射在加拿大光源（萨斯卡通，加拿大）将被应用于量化和定位元素离子，有机溶质和检测其在苜蓿组织中的空间和时间分布。同步辐射傅立叶变换红外光谱（SR-FTIR）将被用来映射的碳水化合物的比例的变化，和-螺旋-折叠蛋白质二级结构。将进行苜蓿叶片中响应于盐胁迫的基因表达的转录组学分析，并基于RNA-seq分析和模式豆科植物蒺藜苜蓿的可用基因组信息，鉴定苜蓿中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豆科牧草。土壤盐分是限制世界上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组成对研究苜蓿的抗逆生理具有重要意义，但目前对盐胁迫下苜蓿组织中的生化组成的定量研究以及盐胁迫下苜蓿组织、细胞和亚细胞水平上的生化组成的空间定位研究还很有限。苜蓿耐盐性的全面认识是培育新品种的需要。 该项目的目标是培养高素质的人才，包括一名牧草应激生理学和同步加速器应用的硕士生和一名博士生。学生在苜蓿基因组学，两个本科毕业论文的学生在实验设计，统计学，植物生理学，和基本的生物技术技能。这一发现将进一步加深我们对紫花苜蓿耐盐生理和遗传的理解。这些基因的鉴定将有助于选育耐盐苜蓿新品种。