Instituto Valenciano de Investigaciones Agrarias (IVIA), Carretera Moncada CV-315, Km 10, Valencia, 46113, Spain.
Plant Genome. 2021 Nov;14(3):e20133. doi: 10.1002/tpg2.20133. Epub 2021 Aug 31.
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.
我们对柑橘属的物种和品种进行了基因组分析，根据柚子（Citrus maxima (Burr. f) Merr）和宽皮橘（Citrus reticulata Blanco）杂种进入祖先基因组的模式，以及在较小规模上的群体遗传测试，确定了几个驯化的决定因素。驯化影响了调节柑橘风味（如酸度）关键成分的基因家族，因为在可食用的橘类品种中，Tajimas 值为负的染色体区域富含与柠檬酸调节相关的基因。从野生亲缘种分化出来的可食用橘类中的扫荡检测表明，驯化减少了涉及氰化和生物碱合成的化学防御，从而提高了适口性。此外，源自柚子基因组的驯化橘类中的一组 SAUR 基因似乎包含控制果实大小的候选基因。同样，纯宽皮橘区域的保守片段也可能对驯化很重要，例如，在第 1 号染色体上的一个片段涉及大多数可食用宽皮橘的无融合生殖。有趣的是，我们的结果还支持了这样一种假设，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了驯化的潜在目标。
