西瓜果肉颜色关键基因LCYB和NCED的功能分析

类胡萝卜素物质的组成和含量直接决定西瓜果肉的颜色，具有抗氧化、抗肿瘤、保护心脑血管等功效。番茄红素和叶黄素是类胡萝卜素的主要成分，是西瓜育种重要的品质性状。本项目组已利用西瓜高代自交系“LSW-177”（红色果肉、高番茄红素）与“COS”（浅黄色果肉、低番茄红素）作为亲本材料，配制F2代群体，开展类胡萝卜素含量QTL分析，获得了决定西瓜果肉红颜色和黄颜色的ClLCYB和ClNCED基因。本项目拟分别采取启动子片段缺失、转录组测序、定点突变、RNAi干涉和过表达等技术手段，研究ClLCYB和ClNCED基因功能。在明确其生物学功能基础上，结合转录组学及代谢通路分析，阐明西瓜果肉颜色形成的分子机理，为探明西瓜果实类胡萝卜素积累和代谢途径奠定基础，进而为改善西瓜颜色等重要品质性状，选育优质西瓜新品种提供重要基因资源。

The composition and content of carotenoids are related with the different flesh colours in watermelon fruit, which have effects of antioxidant, anti-tumor, protecting the cardiovascular and cerebrovascular et al. Lycopene and xanthophylls serve as the main components of carotenoids and they are agronomically important quality characterizations in watermelon breeding. The quantitative trait loci (QTL) analysis of carotenoids content using a F2 population developed from a cross between the two lines of watermelon LSW-177 (red-flesh and high lycopene) and Cream of Saskatchewan (short for ‘COS’, pale-yellow flesh and low lycopene) was performed. Two genes, ClLCYB and ClNCED, determining the red-flesh and yellow-flesh in watermelon fruit, respectively, had been obtained. In the project, the functions of two genes ClLCYB and ClNCED will be identified by promoter analysis, RNA-seq, site-directed mutagenesis, RNAi and over-expression, respectively. Combination these results with physiological measurement and expression profiles of the genes involving in the carotenoids biosynthetic and metabolic pathways will help illuminate the mechanism for flesh colour formation in watermelon. Our research will also provide some basis research for understanding the regulatory mechanism of carotenoids accumulation and degradation in watermelon fruit. Furthermore, it will provide valuable genes resource to improve important quality traits in flesh color of watermelon and to breed new watermelon cultivars of high quality.