REGULATION OF PROVITAMIN A CAROTENOID BIOSYNTHESIS IN MAIZE

玉米中维生素原 A 类胡萝卜素生物合成的调控

• 批准号: 7899407
• 负责人: ELEANORE T WURTZEL
• 金额: $ 32.87万
• 依托单位: HERBERT H. LEHMAN COLLEGE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-08 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7899407
• 关键词: Accounting; Affect; Anabolism; Applications Grants; Area; Basic Science; Blindness; Breeding; Carotene; Carotenoids; Child; Data; Development; Educational workshop; Engineering; Enzymes; Family; Family member; Food; Funding; Gene Expression; Gene Family; Genes; Goals; Grant; Growth and Development function; Health; Human; Investigation; Lead; Maize; Mediating; Membrane; Metabolic; Mixed Function Oxygenases; Modeling; Modification; Nonprovitamin A Carotenoid; Pathway interactions; Plants; Plastids; Poaceae; Provitamin A Carotenoid; Publications; Published Comment; Regulation; Relative (related person); Repression; Research; Rice; Solutions; Staging; Technology; Tissues; Transcript; Transgenic Plants; United States National Institutes of Health; Vitamin A; Vitamin A Deficiency; Wheat; Work; Writing; Xanthophylls; Xerophthalmia; base; enzyme pathway; improved; isoprenoid; mortality; success; tool

DESCRIPTION (provided by applicant): Vitamin A deficiency is a global health problem affecting close to 200 million children. Vitamin A can not be synthesized de novo and it is essential for growth and development; deficiencies manifest as xerophthalmia, blindness, and increased mortality. Plant-derived carotenoids are converted in humans to vitamin A. An approach to alleviating worldwide deficiency is to improve provitamin A carotenoid levels in food staples such as corn, wheat, and rice by metabolic engineering and/or in combination with marker-assisted selection. Preliminary success with metabolic engineering of the pathway in plants points to the potential of this approach. Unexpected products in such transgenic plants, however, suggest that the technology is limited by current deficiencies in understanding of endogenous gene expression. Rational metabolic engineering strategies must take into account the regulation of the endogenous pathway which is not yet completely understood. We propose that the relative accumulation of provitamin A carotenoids is mediated by control of transcript levels for the biosynthetic and degradative enzymes; and that modification (enhancement or repression) of transcript levels in corn endosperm can lead to increased levels of provitamin A carotenoids relative to other non-provitamin A carotenoids. NIH SCORE funding has allowed us to begin to develop tools and research which are most immediately applicable to two of the most important food crops worldwide--corn and rice. We discovered that several pathway enzymes are encoded by small gene families, which raises the question: what is the contribution of gene family members to carotenoid biosynthesis and accumulation in different tissues, developmental stages, and plastid membrane localization? We will continue our NIH-SCORE supported work to conduct a comprehensive investigation of expression of endogenous genes which encode enzymes of the carotenoid pathway and the related isoprenoid biosynthetic pathway which provides substrates for carotenoid biosynthesis. We will also investigate genes encoding enzymes that degrade or modify carotenoids and thus diminish provitamin A content. The proposed research will be divided into two areas: (1) transcript profiling related to carotenoid synthesis/ degradation and correlation with carotenoid content/ composition and (2) characterization of the carotene ring hydroxylases as they impact conversion of provitamin A carotenes to non-provitamin A xanthophylls. Relevance: Vitamin A deficiency is a global health problem affecting close to 200 million children. To alleviate deficiency worldwide, crop plants can be improved for provitamin A carotenoid content, the goal of which requires breeding tools and basic research on how carotenoid composition is regulated in food crops, beginning with corn (maize) and rice as models.

描述（由申请人提供）：维生素A缺乏症是影响近2亿儿童的全球健康问题。维生素A不能从头开始合成，这对于生长和发育至关重要。缺陷表现为眼科，失明和死亡率增加。植物来源的类胡萝卜素在人类中转化为维生素A。减轻全球缺乏症的一种方法是通过代谢工程和/或与标记辅助选择的选择来改善玉米，小麦和大米等食物主食中的类胡萝卜素水平。植物途径代谢工程的初步成功表明了这种方法的潜力。然而，这种转基因植物中的意外产物表明，该技术受到当前理解内源基因表达的缺陷的限制。理性的代谢工程策略必须考虑到尚未完全理解的内源性途径的调节。 我们建议，普罗他胺A类胡萝卜素的相对积累是通过对生物合成和降解酶的转录水平的控制来介导的。玉米胚乳中的转录水平的修饰（增强或抑制）可以导致类胡萝卜素相对于其他非抗毒素A类胡萝卜素的类胡萝卜素的水平升高。 NIH得分资金使我们能够开始开发工具和研究，这些工具和研究最能立即适用于全球两种最重要的食品作物 - 米饭和大米。我们发现，几种途径酶是由小基因家族编码的，这提出了一个问题：基因家族成员对类胡萝卜素生物合成和在不同组织，发育阶段和质体膜定位中积累的贡献是什么？我们将继续对NIH得分支持的工作进行全面研究内源基因的表达，该基因的表达编码类胡萝卜素途径的酶和相关的类异丙生素生物合成途径，该途径为类胡萝卜素生物合成提供了底物。我们还将研究编码降解或修饰类胡萝卜素并因此减少普罗维生胺A含量的酶的基因。拟议的研究将分为两个领域：（1）与类胡萝卜素合成/降解和与类胡萝卜素含量/组合物相关的转录物分析，以及（2）用胡萝卜素环羟化酶表征，因为它们会影响普barot素A类胡萝卜素A类胡萝卜素的转化为非促磷灰素A异植物。 相关性：维生素A缺乏症是影响近2亿儿童的全球健康问题。为了减轻全世界的不足，可以改善农作物植物的类胡萝卜素含量，其目标是需要繁殖工具和基础研究，以了解类胡萝卜素成分如何在粮食作物中调节，从玉米（玉米）和大米作为型号开始。