果实色泽既是外观性状又是营养性状。柑橘果实富含类胡萝卜素，因含有的种类和量的不同呈现各种色泽。柑橘中的柚类，其果肉一般为乳白或淡黄色，近年生产中发现并应用的红肉、黄肉和红皮体细胞突变体是研究果实色泽性状形成与调控机制的良好材料。柚果实色泽变异丰富，但目前对变异原因即类胡萝卜素代谢的关键调控基因还不清楚。本项目拟利用我国特有的一套柚不同色泽（红肉、黄肉和红皮）突变体为材料，从控制色泽变异的遗传位点、调控类胡萝卜素合成基因的转录因子，以及控制类胡萝卜素贮存亚细胞器（有色体）发育的关键基因等三方面开展研究，旨在解析控制柑橘类胡萝卜素代谢的关键因子，发掘关键基因；通过转化播种当年能开花结果的山金柑以及模式作物番茄，评价基因对类胡萝卜素代谢的调控模式、作用及遗传改良潜力。本研究是将我国特有的果树遗传资源转换为基因资源；同时，对深入理解果实色泽变异的分子机制，以及指导色泽遗传改良均具有重要意义。

Fruit color is important for both fruit appearance and nutrition trait. Citrus fruits are rich in carotenoids, and present various colors since with different types and contents of carotenoids. The fruit color of normal pummelo is light yellow or white. The red-, yellow-fleshed and red-albedo mutants found and used in the industry were unusual fruit traits in citrus and attracted broad attentions. These mutants are of significance for their economic, nutritional and research values, particularly ideal materials for the investigation of regulatory mechanism of carotenoid metabolism and fruit color formation. The fruit color of pummelos show abundant variations, but so far the knowledge on the genes in essence regulating carotenoid metabolism is limited. This research will focus on the identification of key genes in controlling carotenoid metabolism, with a unique set of color mutants of pummelo (including yellow-, red-fleshed and red-peeled mutations) recently found in China as the materials. Research contents will include three aspects i.e. the genetic loci responsible for the carotenoid accumulation, transcriptional regulatory factors of carotenoid biosynthetic genes, and the plastid development & differentiated genes during the storage of carotenoids. The candidate genes will be confirmed by functional transformation in Kongkong kumquat (it can set fruits within one year after seed germination), and model fruit crop tomato. Their effects on the regulatory mode and potential in genetic improvement will be evaluated. This research is to transform the unique germplasms into effectual gene(s); at the same time, the results will provide new insight into the molecular mechanism of fruit color mutation, and strengthen the base for the genetic improvement of fruit color.