Role of Abscisic Acid in the Regulation of Root Growth at Low Water Potentials

脱落酸在低水势根系生长调节中的作用

• 批准号: 9306935
• 负责人: Robert Sharp
• 金额: $ 22.25万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9306935&HistoricalAwards=false
• 关键词: Role; Abscisic; Acid; Regulation; Root

9306935 Sharp Studies in the Principal Investigator's laboratory have shown that accumulation of the hormone abscisic acid (ABA) is required for the maintenance of primary root elongation in maize under water-limited conditions. Recent evidence indicates that one role of ABA in this regard is the regulation of proline accumulation for osmotic adjustment. The proposed research aims to determine the cellular mechanisms underlying this relationship. Building upon recent data and a review of the published work in plant as well as animal and bacterial systems, a hypothesis is developed that ABA accumulation in the root growth zone at low water potentials regulates membrane ion transport and intracellular ion levels, which in turn induces mechanisms for growth maintenance including the accumulation of proline. While the role of ABA in regulating ion transport in stomatal guard cells is well-established, such information is scant with regard to the action of ABA in growth regulation. The primary objective is to test this hypothesis using electrophysiological approaches, emphasizing changes in membrane potential and ion concentrations and fluxes in the root growth zone caused by low water potentials and manipulation of endogenous ABA levels. Emphasis will be placed on measurements of K+ and H+. As in previous work, endogenous ABA will be manipulated within physiologically meaningful levels in roots growing at low water potentials using both the inhibitor fluridone and the vp5 mutant of maize to inhibit carotenoid (and ABA) biosynthesis. In all experiments a high degree of spatial resolution will be emphasized to address differential responsiveness to ABA within the root growth zone. Conventional and ion- selective microelectrodes will be used to measure changes in membrane potential, cytoplasmic ion levels and ion transport between roots grown at high and low water potential, and in roots at low water potentials in which endogenous ABA levels are altered. A sol ution culture system has been developed for this work, and preliminary experiments have shown changes in membrane potentials in the root growth zone in response to altered water potentials and to exogenous ABA. The electrophysiological measurements of ion levels will be compared with values obtained by x-ray microanalysis (EDX). Appropriate collaborations have been established to facilitate the electrophysiological and EDX measurements. Parallel to the studies of ionic regulation, the biochemistry of proline accumulation in the root growth zone at low water potentials and as affected by ABA will be examined. The contributions of increased synthesis, decreased catabolism, increased uptake, and decreased incorporation into protein will be assessed. The proposed research is a step toward the long-range goal of identifying specific plant processes or traits which could be used in crop germplasm improvement programs. The studies should provide much needed information in the fields of ABA physiology and root growth regulation under water- limited conditions, which have been characterized by slow progress. ***

9306935 Sharp 首席研究员实验室的研究表明，在水分有限的条件下，需要积累脱落酸（ABA）激素来维持玉米初生根的伸长。 最近的证据表明，ABA 在这方面的作用之一是调节脯氨酸积累以调节渗透压。 拟议的研究旨在确定这种关系背后的细胞机制。 根据最近的数据以及对植物、动物和细菌系统已发表工作的回顾，提出了一种假设，即低水势根部生长区的 ABA 积累调节膜离子转运和细胞内离子水平，进而诱导生长维持机制，包括脯氨酸的积累。 虽然 ABA 在调节气孔保卫细胞离子运输中的作用已得到充分证实，但有关 ABA 在生长调节中的作用的信息却很少。 主要目标是使用电生理学方法检验这一假设，强调低水势和内源 ABA 水平操纵引起的根生长区膜电位、离子浓度和通量的变化。 重点将放在 K+ 和 H+ 的测量上。 与之前的工作一样，使用抑制剂氟啶酮和玉米的 vp5 突变体，在低水势下生长的根部中，将内源 ABA 控制在生理有意义的水平内，以抑制类胡萝卜素（和 ABA）生物合成。 在所有实验中，将强调高度的空间分辨率，以解决根生长区内对 ABA 的差异反应。 传统的离子选择性微电极将用于测量高水势和低水势生长的根之间的膜电位、细胞质离子水平和离子传输的变化，以及内源ABA水平发生改变的低水势根中的离子传输。 这项工作已经开发了溶液培养系统，初步实验表明根生长区膜电位随水势变化和外源 ABA 的变化而变化。 离子水平的电生理测量结果将与 X 射线微量分析 (EDX) 获得的值进行比较。 已建立适当的合作以促进电生理学和 EDX 测量。 与离子调节研究并行，将检查低水势和受 ABA 影响的根生长区脯氨酸积累的生物化学。 将评估合成增加、分解代谢减少、摄取增加和蛋白质掺入减少的贡献。 拟议的研究是朝着确定可用于作物种质改良计划的特定植物过程或性状的长期目标迈出的一步。 这些研究应该为ABA生理学和限水条件下的根系生长调节领域提供急需的信息，但这些领域的进展缓慢。 ***