背景+问题：Although taste is an important aspect of fruit quality, our understanding of its genetic control remains elusive in apple and other fruit crops. 

主要研究：Genomic sequence analysis of 497 Malus accessions revealed an erosion of genetic diversity caused by apple breeding and possible independent domestication events of dessert and cider apples. 

结果1-选择信号：Signatures of selection for fruit acidity and size were detected during the process of both domestication and improvement, but not for fruit sugar content. 

结果2-关键基因：Single mutations in major genes affecting fruit taste, including Ma1, MdTDT, and MdSOT2, dramatically decrease malate, citrate and sorbitol accumulation, respectively, and correspond to important domestication events. 

结果3-Ma1基因功能多效性：The pleiotropic effects of Ma1 on organic acid content and sugar:acid ratio suggest its vital role in determining fruit taste. 

结果4-果实口味与果实大小：Fruit taste is unlikely to have been negatively affected by linkage drag associated with selection for larger fruit that resulted from the pyramiding of multiple genes with minor effects on fruit size. 

结论：Our study provides insights into genetic basis of fruit quality and its evolutionary roadmap during apple domestication, and also points out target genes for fruit taste genetic manipulation.

 摘 要 

尽管口味是果实品质的一个重要指标，但我们对于其在苹果和其它果实作物中潜在的遗传调控机制并不清楚。通过对497份苹果种质材料的全基因组重测序，作者发现苹果育种导致了群体遗传多态性水平的降低，以及甜苹果与酿酒苹果之间发生了独立的驯化事件。在苹果的驯化和改良过程中，作者均能检测到与果实酸度和大小相关的基因受到了选择，但是果实的糖分含量却未受到选择。影响果实口味的主要基因Ma1、MdTDT和MdSOT2的单一突变，会分别显著减少苹果酸、柠檬酸和山梨醇的积累，这三个基因的单基因突变分别对应着重要的驯化事件。Ma1在有机酸含量和糖/酸比率方面具有功能多效性，表明其在决定果实口味中的重要作用。果实口味不太可能受到与选择较大果实的遗传连锁所带来的负面影响，大果实的遗传控制由多个基因聚合而成，每个基因对果实尺寸的影响均较小。本研究揭示了苹果品质的遗传基础及其在驯化过程中的演化路线，并鉴定了果实口味遗传操纵的靶基因。