优质龙眼新品种的缺乏严重削弱了我国龙眼产业在国内外贸易中的竞争力，如何快速培育优质新品种是当今我国龙眼育种中面临的重要问题。项目组2002年创建了‘凤梨朵’ב大乌圆’F1作图群体，对部分品质性状进行了QTL作图，但这些成果还不能直接应用于龙眼品质育种实践中。本项目拟采用连锁作图与全基因组关联分析相结合的策略，深入解析龙眼单果重与可溶性固形物含量的等位变异，项目分两部分进行：(1) 以190份F1分离群体为材料，利用SSR和SNP标记构建高密度、高精度遗传图谱，对龙眼单果重和可溶性固形物含量进行QTL分析；（2）以220份品种资源群体为材料，对单果重和可溶性固形物含量进行全基因组关联分析，确定优异的等位变异。整合连锁分析和全基因组关联分析的结果，获得准确丰富的信息，进一步揭示龙眼单果重和可溶性固形物含量的遗传基础，研究结果将为开展龙眼分子辅助选择加快优质龙眼培育提供材料基础和科学依据。

Longan (Dimocarpus longan Lour.) is an important tropical fruit in China. However, the lack of new longan varieties of high quality severely weakens Chinese trade competitiveness of the longan industry in the world. It is important to shorten longan breeding cycle when cultivating new varieties. An F1 mapping population of ‘Fengliduo’ בDawuyuan’ was created in 2002, and QTL mapping for some fruit quality traits of longan were studied, but these results cannot be applied directly in longan breeding. In this project, dissection of allelic variation of single fruit weight and soluble solids content of longan will be carried out based on linkage map and genome-wide association analysis. There are two parts in this project: (1) A high-density and high-precision genetic map will be constructed with SSR and SNP makers by using single fruit weight and soluble solids content widely separated cross population (190 sexual progenies) as the mapping population. This genetic map will be applied for QTL analysis; (2) Genome-wide association analysis will be employed to dissect single fruit weight and soluble solids content and identify the excellent allelic variation through utilizing a series of longan variety resource (220 varieties). Finally, the molecular mechanisms underlying allelic variation will be illustrated based on the QTL mapping and genome-wide association analysis results. The results will lay foundation for marker assisted selection (MAS) for longan quality improvement and provide potential breeding materials for cultivating new varieties.