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Nature Plants：柑橘驯化过程中花青素生物合成调控基因的演化

已有 4590 次阅读 2018-11-3 09:43 |个人分类:每日摘要|系统分类:论文交流

Subfunctionalization of the Ruby2-Ruby1 gene cluster during the domestication of citrus

First author: Ding Huang; Affiliations: Huazhong Agricultural University (华中农业大学): Wuhan, China

Corresponding author: Qiang Xu

The evolution of fruit colour in plants is intriguing. Citrus fruit has repeatedly gained or lost the ability to synthesize anthocyanins. Chinese box orange (酒饼簕), a primitive (原始的) citrus, can accumulate anthocyanins both in its fruits and its leaves. Wild citrus can accumulate anthocyanins in its leaves. In contrast, most cultivated citrus have lost the ability to accumulate anthocyanins. We characterized a novel MYB regulatory gene, Ruby2, which is adjacent to Ruby1, a known anthocyanin activator of citrus. Different Ruby2 alleles can have opposite effects on the regulation of anthocyanin biosynthesis. AbRuby2Full encodes an anthocyanin activator that mainly functions in the pigmented leaves of Chinese box orange. CgRuby2Short was identified in purple pummelo (柚子) and encodes an anthocyanin repressor. CgRuby2Short has lost the ability to activate anthocyanin biosynthesis. However, it retains the ability to interact with the same partner, CgbHLH1, as CgRuby1, thus acting as a passive (被动的) competitor in the regulatory complex. Further investigation in different citrus species indicated that the Ruby2-Ruby1 cluster exhibits subfunctionalization among primitive, wild and cultivated citrus. Our study elucidates the regulatory mechanism and evolutionary history of the Ruby2-Ruby1 cluster in citrus, which are unique and different from that found in Arabidopsis, grape or petunia.

植物果实的颜色演化很不是很清楚。柑橘的果实在演化过程中重复地获得、丢失合成花青素的能力。酒饼簕是柑橘属比较原始的种，能够在叶子和果实中积累花青素。柑橘野生种能够在叶片中积累花青素。相反，大多数的栽培种柑橘丢失了积累花青素的能力。本文作者鉴定了一个新的MYB调控基因Ruby2，与另一个已知的花青素激活子Ruby1基因毗邻。不同的Ruby2基因对于花青素的生物合成具有完全相反的调控作用。AbRuby2Full基因编码一个花青素激活子，作用于酒饼簕叶片中的色素积累。紫柚中的CgRuby2Short基因编码一个花青素抑制子。CgRuby2Short蛋白丢失了激活花青素生物合成的能力，但其仍然保留着与CgRuby1互作蛋白CgbHLH1结合的能力，因此是被动的竞争者。进一步的研究显示Ruby2-Ruby1基因簇在原始种、野生种和栽培种柑橘中存在亚功能化。本文的研究揭示了Ruby2-Ruby1基因簇在柑橘中的演化历史和调控机制，这是不同于拟南芥、葡萄及矮牵牛中的特有机制。