Cultivated strawberry is one of the important commercial fruits not only in Japan, but around the world. Even so, analyzing regions responsible for fruit quality traits of cultivated strawberry has been very challenging due to the alloploidy and octoploidy of genome conformation. In order to solve this problem, we previously developed a strawberry multi-parent advanced generation inter-cross (MAGIC) population derived from crosses involving six cultivars. Here, we performed genotyping of the MAGIC population with simple sequence repeat (SSR) markers, which were generated from an expressed sequence tag site, and conducted a genome-wide association study of 13 strawberry fruit quality-related traits to reveal associated quantitative trait loci (QTLs). Correlation coefficients among fruit color-related traits, such as fruit surface color (FSC), fruit surface anthocyanin content (FSA), and fruit flesh anthocyanin content (FFA) were relatively higher, but FSC, FSA, and FFA did not show any higher correlation with other traits. Fruit weight (FW), FSC, and fruit firmness, including whole fruit firmness (WFF), fruit surface firmness (FSF), and fruit flesh firmness (FFF), indicated higher year to year correlation coefficients than other fruit quality-related traits. Among FW, FSC, and WFF, there were only two QTLs for FW, five for FSC, and 38 for WFF (the most) and they were detected on all chromosomes. QTLs for some traits shared common flanking simple sequence repeat markers, and allelic differences of one marker affected the variation of other traits. QTLs for fruit firmness were most frequently detected, followed by those for SSC and titratable acidity (TA). Allelic differences in these QTLs negatively affected FSC, the fruit surface anthocyanin content (FSA), and fruit flesh anthocyanin content (FFA), implying that alleles which increase fruit firmness, SSC, and TA lighten fruit color. Similarly, QTLs for FSC, FSA, and FFA mostly negatively affected FSF, FFF, SSC, and TA and did not affect WFF. This indicated that simultaneous improvement in fruit firmness, SSC, and TA is possible with many markers, but improving fruit firmness and deepening fruit color are highly challenging.

栽培草莓不仅在日本而且在世界范围内都是重要的商业水果之一。即便如此，由于基因组构象的异倍体和八倍体，分析负责栽培草莓果实品质性状的区域仍然非常具有挑战性。为了解决这个问题，我们先前开发了一个草莓多亲代杂交（MAGIC）种群，该种群来自涉及六个品种的杂交。在这里，我们用表达序列标签位点产生的简单序列重复（SSR）标记对MAGIC群体进行了基因分型，并对13个草莓果实品质相关性状进行了全基因组关联研究，以揭示相关的定量性状位点（QTL）。果实颜色相关性状之间的相关系数，例如果实表面颜色（FSC），水果表面花青素含量（FSA）和果肉花色苷含量（FFA）相对较高，但FSC，FSA和FFA与其他性状没有任何相关性。水果重量（FW），FSC和水果硬度，包括完整水果硬度（WFF），水果表面硬度（FSF）和果肉硬度（FFF），表明年际相关系数高于其他与水果品质相关的性状。在FW，FSC和WFF中，FW只有两个QTL，FSC有五个，WFF有38个（最多），并且在所有染色体上均被检测到。一些性状的QTL共有共同的侧翼简单序列重复标记，而一个标记的等位基因差异影响其他性状的变异。水果硬度的QTL最常见，其次是SSC和可滴定酸度（TA）。这些QTL中的等位基因差异会对FSC，果实表面花青素含量（FSA）和果肉花色苷含量（FFA）产生负面影响，这意味着增加果实硬度，SSC和TA的等位基因会减轻果实的颜色。同样，FSC，FSA和FFA的QTL对FSF，FFF，SSC和TA的影响最大，而对WFF没有影响。这表明使用许多标记可以同时提高果实硬度，SSC和TA，但提高果实硬度和加深果实色具有高度挑战性。