One Piece at a Time: Flavonol Deglycosylation and Peroxidation in Abiotic Stressed Plants

一次一件：非生物胁迫植物中的黄酮醇去糖基化和过氧化作用

• 批准号: RGPIN-2020-04031
• 负责人: Bozzo, Gale
• 金额: $ 2.4万
• 依托单位: University of Guelph
• 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=716620
• 关键词: Piece; Time; Flavonol; Deglycosylation; Peroxidation

Heat and drought stresses in agricultural fields culminate in damaged crops and billions of dollars in economic losses across North America. These stresses and the deleterious effects they elicit in plants are expected to intensify with global climate change. This will have negative consequences for global food security in the absence of improved environmental stress tolerance mechanisms. Typically, plants accumulate reactive oxygen species (ROS) under environmental stress, which results in cellular and tissue damage that limit growth and development. An increase in ascorbate levels is a hallmark response to oxidative stress, although this metabolic adjustment is not sustained. Thus many agricultural systems lack the metabolic flexibility to offset ROS damage. In order to improve tolerance to combined drought and heat stress, it is imperative to identify the biochemical and molecular properties of alternative ROS detoxification mechanisms. Our research program is focused on endogenous oxidative stress mechanisms that occur in plants subjected to environmental perturbations; a central theme is the study of metabolic processes that affect the distribution of flavonol glycosides in plants. Flavonol glycosides are specialized metabolites that amass in plants affected by oxidative stress, including during heat and drought exposure. Flavonol glycosides have little antioxidant potential, and thus it is postulated that degradation of these compounds is required to produce the flavonol aglycone moiety that would participate in anti-oxidation. We have previously identified a -glucosidase (BGLU) activity that initiates the hydrolysis of glucosylated flavonols (e.g., kaempferol 3-O--glucoside-7-O--rhamnoside) in plants. The transient accumulation of BGLU catabolites (e.g., kaempferol 7-O--rhamnoside) as well as in planta conversion of kaempferol to smaller molecules (i.e., 4-hydroxybenzoate) implies continual degradation of flavonols by -rhamnosidase and peroxidase activities. We propose that the concerted action of these -rhamnosidase and peroxidase activities would supply flavonol aglycones (e.g., kaempferol) for ROS detoxification during abiotic stress. Our aim is to elucidate the biochemical properties of plant flavonol 7-O--rhamnoside -rhamnosidases and flavonol peroxidases. A second aim is to define the functional importance of these degradative mechanisms for flavonol turnover and sequestration of ROS during various abiotic stresses, such as combined heat and drought. The research will provide new biochemical and molecular targets for biotechnology strategies aimed at improving environmental stress tolerance in agricultural systems. The proposed research will provide unique training opportunities for 2 PhD, 3 MSc and 3 BSc in multi-disciplinary research, including classical biochemistry, molecular biology, analytical chemistry, and genomics, technological skills that are in high demand within the scientific industry sector.

农业领域的热量和干旱压力最终导致北美损坏的农作物和数十亿美元的经济损失。这些压力及其在植物中产生的有害影响预计会随着全球气候变化而加剧。在没有改善的环境压力耐受性机制的情况下，这将对全球粮食安全产生负面影响。通常，植物在环境压力下积累活性氧（ROS），从而导致细胞和组织损伤限制生长和发育。抗坏血酸水平的提高是对氧化应激的标志反应，尽管这种代谢调整尚未持续。因此，许多农业系统缺乏抵消ROS损害的代谢灵活性。为了提高对干旱和热应激的耐受性，必须确定替代性ROS解毒机制的生化和分子特性。我们的研究计划的重点是内源性氧化应激 发生环境的植物中发生的机制 扰动；一个中心主题是研究代谢过程 影响黄酮醇在植物中的分布。黄酮醇糖苷是专门的代谢物，在受氧化应激影响（包括在热和干旱暴露期间）积聚的植物中积聚。黄酮醇糖苷几乎没有抗氧化剂的潜力，因此据推测，这些化合物的降解需要产生可以参与抗氧化的黄酮醇aglycone部分。我们先前已经鉴定出一种葡萄糖基化黄酮醇（例如Kaempferol 3-O--葡萄糖苷-7-O-Rhamnoside）在植物中启动葡萄糖基化黄酮醇的水解的 - 葡萄糖苷酶（BGLU）活性。 BGLU分解代谢物（例如Kaempferol 7-O-rhamnoside）以及Kaempferol转化为较小的分子（即4-羟基苯甲酸酯）的瞬时积累暗示了Flavonols通过-Rhamnosidase和Peroxidase Casase和Peroxidase casse and-ramnoxise and peroxidase和Peroxidase的持续去散发。我们建议这些-Rhamnosidase和过氧化物酶活性的一致作用将在非生物胁迫期间提供黄酮醇aglycones（例如Kaempferol）用于ROS排毒。我们的目的是阐明植物黄酮7-O--Rhamnoside-rhamnosidass和黄酮醇过氧化物酶的生化特性。第二个目的是定义这些降解机制在各种非生物胁迫（例如联合热量和干旱）期间的降解机制的功能重要性。这项研究将为生物技术策略提供新的生化和分子靶标，旨在提高农业系统中的环境压力耐受性。拟议的研究将为多学科研究提供独特的培训机会，其中包括经典生物化学，分子生物学，分析化学和基因组学，技术技能在科学行业中需求很高。