Elucidating molecular mechanisms by which seeds respond to environmental factors

阐明种子响应环境因素的分子机制

• 批准号: RGPIN-2014-03621
• 负责人: Nambara, Eiji
• 金额: $ 2.48万
• 依托单位: University of Toronto
• 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=660627
• 关键词: Elucidating; molecular; mechanisms; seeds; respond

Plant hormones are low abundant signal molecules, which significantly influence a variety of processes in plant growth and development. Functional genomics research in cereals has revealed that key genetic loci for yield production and stress responses selected by the classical breeding include a series of hormone metabolism and signaling genes. The plant hormone metabolism is regulated by a number of environmental factors and plays an important role in tuning plant growth in response to changing environment. Current challenge in plant biology and biotechnology is to understand how plants sense the environmental factors and alter the plant hormone metabolism. The Nambara research group studies how plants control cellular concentrations of the plant hormone levels with a focus on abscisic acid (ABA) metabolism. We use Arabidopsis seed germination as a model system, because seeds have sophisticated mechanisms to sense environmental conditions. Mature, dry seeds contain all the components required to resume the plant's life cycle in an appropriate environment. The seeds sense water, nutrients, temperature, after-ripening, and light to determine if the appropriate germination environment exists, and a change in these external cues alters plant hormone metabolism and signaling, which determine whether seeds germinate or remain dormant. The proposed research aims to elucidate the molecular mechanisms by which seeds sense environmental signals and regulate plant hormone metabolism, with a focus on how nitrate regulates ABA catabolism and seed germination.* Nitrate is a major nitrogen source existing in soil and influences plant growth and development as a nutrient and as a signal. As a nutrient, nitrate is assimilated to ammonium and then incorporated into amino acids. As a signal, low nitrate concentration causes rapid reprogramming of genome-wide gene expression, even in mutants defective in nitrate assimilation. Nitrate promotes seed germination in many plant species. The effect of nitrate on germination can be observed in mutants defective in nitrate assimilation. This indicates that it acts as a signal to stimulate germination. My research group previously reported that nitrate activates ABA catabolism and reduces ABA, an inhibitor of germination. Despite recent identification of essential genes for nitrate sensing and signal transduction, the molecular mechanisms by which nitrate regulates ABA catabolism remain largely unknown.* The overall goal of this grant is to investigate the molecular and cellular mechanisms involved in nitrate regulation of ABA metabolism and seed germination. My research group has recently identified the novel factor regulating these processes during Arabidopsis seed germination. We will elucidate the molecular function of the regulators in nitrate signaling in seeds. Stable crop yield under nitrate limited condition is a key target for plant biotechnology, because sustainable agricultural practices must limit expensive and potentially polluting nitrate inputs. Our basic research will help to gain a novel solution to increase crop yield and decrease crop losses.

植物激素是低丰富的信号分子，这显着影响植物生长和发育中的各种过程。谷物中的功能基因组学研究表明，用于产量产生的关键遗传基因座和经典育种选择的应力反应包括一系列激素代谢和信号基因。植物激素的代谢受许多环境因素的调节，并在对环境变化的响应中调整植物生长中起着重要作用。植物生物学和生物技术的当前挑战是了解植物如何感知环境因素并改变植物激素代谢。 Nambara研究小组研究了植物如何控制植物激素水平的细胞浓度，重点是脱甲酸（ABA）代谢。我们将拟南芥种子发芽作为模型系统，因为种子具有复杂的机制来感知环境条件。成熟的干燥种子包含在适当的环境中恢复植物生命周期所需的所有组件。种子感觉水，养分，温度，成熟和光，以确定是否存在适当的发芽环境，这些外部提示的变化改变了植物激素的代谢和信号传导，这决定了种子是发芽还是保持休眠状态。拟议的研究旨在阐明种子感知环境信号并调节植物激素代谢的分子机制，重点是硝酸盐如何调节ABA分解代谢和种子发芽。作为一种营养素，将硝酸盐吸收到铵中，然后掺入氨基酸中。作为信号，低硝酸盐浓度会导致全基因组基因表达的快速重编程，即使在硝酸盐同化有缺陷的突变体中。硝酸盐促进许多植物物种中的种子发芽。硝酸盐对发芽的影响可以观察到硝酸盐同化有缺陷的突变体。这表明它是刺激发芽的信号。我的研究小组先前报道说，硝酸盐会激活ABA分解代谢，并降低了一种发芽抑制剂ABA。尽管最近鉴定出硝酸盐感应和信号转导的必需基因，但硝酸盐调节ABA分解代谢的分子机制仍然在很大程度上未知。我的研究小组最近确定了在拟南芥种子发芽期间调节这些过程的新因素。我们将阐明调节剂在种子中硝酸盐信号传导中的分子功能。硝酸盐有限条件下的稳定农作物产量是植物生物技术的关键目标，因为可持续的农业实践必须限制昂贵且可能污染硝酸盐输入。我们的基础研究将有助于获得一种新的解决方案，以增加农作物产量并减少作物损失。