控制柑橘果实红色性状的关键基因及其调控机制

色泽是园艺产品重要的外观和品质性状。本研究以我国南方第一大果树柑橘为研究对象，以课题组搜集的色泽自然突变体和构建的色泽分离群体为试材，采用遗传学和功能基因组学等手段，从果皮和果肉两个角度研究柑橘类胡萝卜素代谢影响果实红色性状形成的机制。研究内容包括三个方面：柚红色果肉性状形成的关键位点发掘与调控机制；LCYB2（番茄红素β-环化酶）的两个等位基因差异表达导致果肉番茄红素积累呈现红色的调控机制；以及乙烯和低温如何调控CCD4b（类胡萝卜素裂解双氧合酶）基因，使C40类胡萝卜素降解为C30脱辅基类胡萝卜素形成红色果皮的机制。项目旨在弄清楚柑橘果实红色性状形成基础和调控机理，为丰富人们对类胡萝卜素代谢调控的认识、改良果实色泽提供理论支撑，同时项目的实施对于提升柑橘乃至其它园艺产品的品质和育种效率均具有重要意义。

Color is an important trait of both out-appearance and internal-quality for horticultural crops. This research will focus on the fruit color of citrus, the number one fruit crop in south China. By using the previously exploited spontaneous color mutants as well as the color segregating populations of citrus as the materials, the research will dissect the mechanism conferring the carotenoid biogenesis related to the formation of pink-flesh and red peel of fruit by utilizing classic genetic and functional genomics approaches. The research contents will include three sub-topics: Excavating the key loci (genes) conferring the pink-flesh of pummelo, and identifying its working mechanism; Understanding the mechanism underlying the differential expression of two alleles of gene CsLCYB2 on the lycopene accumulation in fruit flesh; And dissecting how the ethylene and low temperature affect the CCD4b expression, as will cleavage the C40 carotenoid to citraurin, a C30 apo-carotenoid showing deep red color on the peel. This research aims at understanding the mechanism for red color of citrus fruit; as will benefit the genetic improvement of color trait, and provide support for enhancing the fruit quality via culture practice. This research will have great significance in fruit quality both for citrus and for other horticultural crops.