果实重量是番茄产量构成的重要因素，培育大果的品种是番茄育种的重要目标之一。因此，对控制果实重量的关键基因进行克隆及功能分析，不但有助于阐明番茄果实发育的分子机制，而且对于指导番茄的丰产育种也具有重要的意义。申请人长期从事番茄果实重量驯化与分子改良研究。最近定位了一个影响果实重量的显性主效QTL fw6.3。它可使果实重量增加35.2%，其遗传贡献率（R2值）可达0.118，d/a值可达1.053。它已被定位在6号染色体248 kb的区段内。本项目拟在此基础上，对FW6.3基因进行图位克隆及转基因功能互补验证；结合360份番茄材料重测序结果，分析FW6.3基因的自然变异形式及进化模式；结合其不同等位基因对产量相关性状、果实细胞数量和大小、果实组织转录组的影响，分析FW6.3基因的功能。研究结果不仅有助于阐明番茄果实重量形成的分子机理，而且为番茄遗传改良提供了重要的基因资源。

Fruit weight is an important component of tomato yield. The development of variety with large fruit is hence one of the most important goals of tomato breeding. Therefore, map-based cloning and functional analysis of the key genes that control fruit weight will not only help to clarify the molecular mechanism of tomato fruit development, but also have important practical significance for tomato breeding. The applicant of this project has been studying the domestication and genetic improvement of tomato fruit weight for many years. Recently, the applicant identified the fruit weight 6.3 (fw6.3), a major dominant quantitative trait locus (QTL) controlling fruit weight in tomato, through QTL-seq and traditional QTL mapping. fw6.3 could increase fruit weight by up to 35.2%. fw6.3 also could account for 1.053 of d/a valule and 0.118 of R2 valule (an index represents the phenotypic variation explained by the QTL). fw6.3 has been narrowed down to a 248 kb region on chromosome 6. This project will ⑴ determine FW6.3 gene through fine-mapping and transgenic complementation test; ⑵ Examine the evolutionary history of the fw6.3 locus through the molecular diversity and phylogenetic analysis of FW6.3 gene; ⑶ Analyze the function of FW6.3 gene through comparing the yield-related traits, fruit cell number and cell size, transcriptome of the fruits of wild type, fw6.3 near isogenic line, and transgenic line. The results of this project will not only facilitate us to understand the molecular mechanisms controlling cell size in tomato fruit, but also provide an important genetic recourse for tomato genetic improvement.