‘Micro-Tom’, a dwarf tomato cultivar, has been used as a convenient model system in tomato research. Previous studies have shown that several genes are involved in the phenotype, but to date no study has focused on the fruit weight. In this study, we tried to clarify genetic factors that regulate the fruit weight of ‘Micro-Tom’ using an F₂ population derived from ‘Micro-Tom’ and ‘MPK-1’, a mid-size tomato cultivar. The F₂ population showed a continuous and transgressive segregation in terms of fruit weight, suggesting that the fruit weight was regulated by multiple loci. To identify these loci, quantitative trait loci (QTL) analysis was performed. Three QTLs located on chromosomes 4, 7, and 9 were found to regulate fruit weight, and were designated as qfw4.1, qfw7.1, and qfw9.1. Of these QTLs, qfw4.1 exhibited the highest logarithm of the odds score. We confirmed the effect of qfw4.1 in the F₃ population and showed that it regulates fruit weight without affecting locule number. In addition, being homozygous for the Micro-Tom allele at the marker linked to qfw4.1 reduced vegetative size, suggesting that qfw4.1 regulates not only fruit weight, but also vegetative size in ‘Micro-Tom’.

矮番茄品种'Micro-Tom'已被用作番茄研究中的便捷模型系统。先前的研究表明，该表型涉及多个基因，但迄今为止，尚无研究集中在果实重量上。在这项研究中，我们试图通过使用来自中等大小番茄品种'Micro-Tom'和'MPK-1'的F ₂种群来阐明调节'Micro-Tom'果实重量的遗传因素。F ₂种群在果实重量方面表现出连续和侵略性的分离，表明该果实重量受多个基因座调控。为了鉴定这些基因座，进行了数量性状基因座（QTL）分析。发现位于染色体4、7和9上的三个QTL调节果实重量，并命名为qfw4.1，qfw7.1和qfw9.1。在这些QTL中，qfw4.1展示了几率最高的对数。我们证实了qfw4.1在F ₃种群中的作用，并表明它在不影响子房数的情况下调节果实重量。此外，与qfw4.1连锁的标记处的Micro-Tom等位基因是纯合的，可减少植物的营养大小，这表明qfw4.1不仅可调节'Micro-Tom'的果实重量，而且还可调节其营养大小。