Functional Analysis of Plant Carotenoid Dioxygenases

这一建议解决了一类酶的功能被称为类胡萝卜素切割双加氧酶（ccd）。这些酶代谢类胡萝卜素，产生大量的分子，这些分子在食品工业中作为着色剂和调味剂具有重要的经济意义。这些酶的产物，通常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。四种功能未知的CCD酶（CCD1、CCD4、CCD7和CCD8）一直是研究的重点。迄今为止的研究表明，CCD1对多种类胡萝卜素底物的9,10（9',10'）裂解是番茄和矮牵牛挥发物和风味成分的主要来源。CCD1还在调节谷物中具有重要营养价值的类胡萝卜素（如β -胡萝卜素）的积累中发挥重要作用。CCD7和CCD8的突变导致植物生长发生重大变化，特别是植物产生分支的能力。因此，CCD7和CCD8共同作用合成一种新的，尚未确定的类胡萝卜素激素。接下来的工作将有三个关键目标：1)一个综合的、多层次的策略，旨在鉴定由CCD7/CCD8合成的生物活性化合物。2) CCD7和CCD8在不同植物物种中的功能比较分析。3) CCD4的功能分析，明确其底物特异性及其在叶片发育中的作用。更广泛的影响：这项工作已经产生了对人类营养、味觉和香气至关重要的材料。一项旨在增加谷类谷物中类胡萝卜素含量的合作也已启动，这有可能对发展中国家产生影响。这项研究将被用作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 proposal addresses the functions of a class of enzymes known as carotenoid cleaving dioxygenases (CCDs). These enzymes metabolize carotenoids, creating a vast array of molecules that are economically important in the food industry as colorants and contribute to flavor. The products of these enzymes, generally known as 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 the major scent volatiles in roses. Four CCD enzymes (CCD1, CCD4, CCD7 and CCD8) of unknown function have been the focus of research. Studies to date have shown that 9,10 (9',10') cleavage of diverse carotenoid substrates by CCD1 is a major source of volatiles and flavor constituents in tomato and petunia. CCD1 also plays a major role in regulating accumulation of nutritionally important carotenoids such as beta-carotene in cereal grains. Mutations in CCD7 and CCD8 cause major alterations in plant growth, particularly in the ability of the plant to make branches. Therefore, It has been concluded that CCD7 and CCD8 act together in the synthesis of a novel, and as yet unidentified, apocarotenoid hormone. The continuing work will have three key objectives: 1) An integrated, multitiered strategy aimed at identifying the biologically active compound synthesized by the CCD7/CCD8. 2) Comparative analysis of CCD7 and CCD8 function in divergent plant species. 3) Functional analysis of CCD4 with goals of defining its substrate specificity and its role in leaf development.Broader Impacts: The work has already generated material that will be fundamentally important to human nutrition, taste and aroma. A collaboration aimed at increasing carotenoid content in cereal grains that has the potential to impact the developing world has also been initiated. This research will be used as a platform to educate undergraduate and graduate students, including minority students from Fort Valley State University, an 1890 Land-Grant University.