色泽新颖、鲜艳和独特能够增强果实的视觉吸引力及市场竞争力。琯溪蜜柚果皮橙色 （orange-peel）和果肉橙色（orange-flesh）突变体是田间自然发生的极具特色的色泽突变材料。两者系来源于同一野生型的体细胞突变体，均大量积累β-胡萝卜素，但一种突变体是果皮突变，而另一种突变体则仅仅是果肉突变。目前对这种自发性的组织特异突变机制还知之甚少。本项目拟利用基因组导向的体细胞突变位点检测工具挖掘突变区域；通过全基因组关联分析和遗传定位剖析控制果皮和果肉橙色性状的遗传位点；筛选控制橙色性状的关键基因并进行功能分析；对获得表型的基因进一步利用蛋白质-蛋白质和蛋白质-DNA互作技术解析其调控机理，阐明柑橘果实不同组织层发生橙色突变的机理。本研究将进一步深化对柑果类果实色泽变异的认识，在理论上具有创新性；另一方面获得的色泽调控基因和途径将为柑橘果实色泽改良提供依据。

Fruit color novelty, brightness and uniqueness can improve visual attractiveness and market competitivity. Orange-peel and orange-flesh mutants of citrus grandis 'Guanxi' are typically featured citrus varieties which are originated from spontaneous mutations. Both of them are somatic mutants derived from the same wild type, but accumulate massive β-carotene in different tissues. One shows peel-specific mutational pattern, while the other mutant is flesh-specific. Little is known about this kind of tissue-specific pattern of spontaneous mutation. This study will employ genome-guided somatic mutation detection tools to pinpoint the mutational region(s); utilize genome wide association analysis and genetic mapping strategy to narrow down the genetic loci controlling orange color trait in peel and flesh; perform functional characterization of the candidate genes and investigate the regulatory mechanism of key gene by protein-protein and protein-DNA experiments. This study will elucidate the mechanisms behind the tissue-specific mutations. The outcome will deepen the understanding of color mutations in different tissue layers in citrus fruits; meanwhile provide the characterized key genes or pathways for genetic improvement of citrus fruit color.