We performed genomic analyses on species and varieties of the genus Citrus to identify several determinants of domestication, based on the pattern of pummelo [Citrus maxima (Burr. f) Merr] and mandarin (Citrus reticulata Blanco) admixture into the ancestral genome, as well as population genetic tests at smaller scales. Domestication impacted gene families regulating pivotal components of citrus flavor (such as acidity) because in edible mandarin varieties, chromosome areas with negative Tajimas values were enriched with genes associated with the regulation of citric acid. Detection of sweeps in edible mandarins that diverged from wild relatives indicated that domestication reduced chemical defenses involving cyanogenesis and alkaloid synthesis, thus increasing palatability. Also, a cluster of SAUR genes in domesticated mandarins derived from the pummelo genome appears to contain candidate genes controlling fruit size. Similarly, conserved stretches of pure mandarin areas were likely important as well for domestication, as, for example, a fragment in chromosome 1 that is involved in the apomictic reproduction of most edible mandarins. Interestingly, our results also support the hypothesis that various genes subject to selective pressure during evolution or derived from whole genome duplication events later became potential targets of domestication.

中文翻译：

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塑造柑橘的生物学：II。驯化的基因组决定因素

我们基于柚子 [ Citrus maxima (Burr. f) Merr] 和普通话 ( Citrus reticulataBlanco) 混合到祖先基因组中，以及小规模的群体基因测试。驯化影响了调节柑橘风味关键成分（如酸度）的基因家族，因为在食用柑橘品种中，具有负 Tajimas 值的染色体区域富含与调节柠檬酸相关的基因。检测到与野生近缘种不同的可食用柑桔表明，驯化减少了涉及生氰和生物碱合成的化学防御，从而增加了适口性。还有一个SAUR集群来自柚基因组的驯化柑橘中的基因似乎包含控制果实大小的候选基因。同样，保守的纯橘子区域可能对驯化也很重要，例如，1 号染色体上的一个片段参与了大多数可食用橘子的无性生殖。有趣的是，我们的结果也支持这样的假设，即在进化过程中受到选择压力或源自全基因组复制事件的各种基因后来成为驯化的潜在目标。