Functional Analysis of Plant Carotenoid Dioxygenases

该项目解决了一类被称为类胡萝卜素切割双加氧酶（ccd）的酶的功能。这些酶代谢类胡萝卜素，产生大量具有重要经济意义的分子。这些酶的一些产物，被称为类伪胡萝卜素，在植物和动物中也有生物活性。重要的类伪胡萝卜素包括动物中的类维生素a，植物中的脱落酸，藏红花中的主要着色剂和风味化合物，以及玫瑰中的主要气味挥发物。研究人员专注于四种CCD酶（CCD1, CCD4， CCD7和CCD8）。其中两种酶，CCD1和CCD4似乎在风味和气味挥发物的合成中起作用。它们在类胡萝卜素转换中也有尚未确定的作用。失去这两个基因产物中的任何一个都能显著提高种子的类胡萝卜素含量。该项目将解决这两种酶的功能，因为它与类胡萝卜素含量有关，有可能增强某些食物的营养成分。表征CCD1生化活性的技术是在之前的资助期间开发的。这些技术现在将应用于CCD4的生化表征。CCD7和CCD8协同作用，合成一种尚未确定的新型植物激素，调节植物产生分支的能力。研究人员和合作者的一个主要目标是鉴定由CCD7/CCD8合成的生物活性化合物。除了从植物组织中分离激素外，还将确定CCD7和CCD8的生化特性和底物偏好。一个相关的目标是表征CCD7和CCD8玉米群体内的自然变异。更广泛的影响：该项目有望为CCD酶的功能提供基本的见解。了解这些酶在体内的作用对改善食物的风味和营养具有很大的潜力，特别是在发展中国家。该项目也有可能鉴定出一类全新的调节植物结构的植物激素。这项研究是一个教育本科生和研究生的平台，包括来自1890年土地授予大学的福特谷州立大学的少数民族学生。

This project addresses the functions of a class of enzymes known as carotenoid cleaving dioxygenases (CCDs). These enzymes metabolize carotenoids, creating a vast array of economically important molecules. Some of the products of these enzymes, called apocarotenoids, also have biological activity in plants and animals. Important apocarotenoids include retinoids in animals, abscisic acid in plants, the major colorant and flavor compound in saffron, and major scent volatiles in roses. The investigators have focused on four CCD enzymes (CCD1, CCD4, CCD7 and CCD8). Two of the enzymes, CCD1 and CCD4 appear to function in synthesis of flavor and scent volatiles. They also have as yet undefined roles in carotenoid turnover. Loss of either of these two gene products significantly increases the carotenoid content of seeds. The project will address the functions of these two enzymes as it relates to carotenoid content with the potential to enhance the nutritional composition of some foods. Techniques for characterizing the biochemical activity of CCD1 were developed during the prior funding period. These techniques will now be applied to biochemical characterization of CCD4. CCD7 and CCD8 act coordinately to synthesize an as yet unidentified novel plant hormone that regulates the ability of the plant to make branches. A major goal of the investigators, together with collaborators, is to identify the biologically active compound synthesized by the CCD7/CCD8. In addition to isolation of the hormone from plant tissue, the biochemical properties and substrate preferences of CCD7 and CCD8 will be determined. A related goal is to characterize the natural variance within maize populations of CCD7 and CCD8. Broader Impacts: The project is expected to provide fundamental insights into the functions of the CCD enzymes. Understanding the roles of these enzymes in vivo has great potential to improve both flavor and nutrition of foods, especially in the developing world. The project also has the potential to identify an entirely new class of plant hormones that regulate plant architecture. This research is a platform to educate undergraduate and graduate students, including minority students from Fort Valley State University, an 1890 Land-Grant University.