Subfunctionalization of duplicate MYB genes in Solanum commersonii generated the cold-induced ScAN2 and the anthocyanin regulator ScAN1
Subfunctionalization of duplicate MYB genes in Solanum commersonii generated the cold-induced ScAN2 and the anthocyanin regulator ScAN1
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DOI：
10.1111/pce.12966
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发表时间：
2018-05-01
影响因子：
7.3
通讯作者：
Carputo, Domenico
中科院分区：
文献类型：
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作者：
D'Amelia, Vincenzo;Aversano, Riccardo;Carputo, Domenico
野生马铃薯是栽培马铃薯缺乏等位基因多样性和基因座的有效来源。在这些物种中，叶片中花青素的存在与更强的耐寒性有关。然而，使土豆抵御寒冷暴露的分子机制仍不清楚。在这里，我们证明了MYB转录因子AN2在野生、耐寒的商业茄子中被低温诱导表达，而在敏感的茄子品种中不被诱导。我们发现，AN2是马铃薯花青素调节因子AN1的平行对数，表现出与碱性螺旋-环-螺旋(BHLH)共伴侣相似的相互作用能力。它们的序列多样性导致了在烟草中测试时促进酚类物质积累的不同能力。事实上，功能研究表明，AN2诱导花青素的能力不如AN1，但它有很强的诱导羟基肉桂酸衍生物积累的能力。我们认为，R2R3MYB基因的重复导致了随后的亚功能化，其中AN1专用于花青素的产生，而AN2保存了对冷胁迫的反应能力，主要诱导羟基肉桂酸衍生物的合成。这些结果有助于理解基因复制在酚类化合物调控中的进化意义。本文从功能上分析了马铃薯花青素平行MYB基因scan2和scan1的差异以及前者对低温的响应。这些是它强调的主要相关方面：(1)ScAN2和SCAN1的历史演变，其中ScAN2只在耐寒的商业茄子中保持冷诱导的能力，而在敏感的茄子中不被诱导；(2)ScAN2及其伴生体SCAN1在异源系统中激活花青素的不同功能；(3)ScAN2激活羟基肉桂酸衍生物的能力，羟基肉桂酸衍生物是木质素和次生素生产的重要前体，以及已知的面临环境胁迫的化合物。
Wild potato species are useful sources of allelic diversity and loci lacking in the cultivated potato. In these species, the presence of anthocyanins in leaves has been associated with a greater tolerance to cold stress. However, the molecular mechanisms that allow potatoes to withstand cold exposure remain unclear. Here, we show that the expression of AN2, a MYB transcription factor, is induced by low temperatures in wild, cold-tolerant Solanum commersonii, and not in susceptible Solanum tuberosum varieties. We found that AN2 is a paralog of the potato anthocyanin regulator AN1, showing similar interaction ability with basic helix-loop-helix (bHLH) co-partners. Their sequence diversity resulted in a different capacity to promote accumulation of phenolics when tested in tobacco. Indeed, functional studies demonstrated that AN2 is less able to induce anthocyanins than AN1, but nevertheless it has a strong ability to induce accumulation of hydroxycinnamic acid derivatives. We propose that the duplication of R2R3 MYB genes resulted in subsequent subfunctionalization, where AN1 specialized in anthocyanin production and AN2 conserved the ability to respond to cold stress, inducing mainly the synthesis of hydroxycinnamic acid derivatives. These results contribute to understanding the evolutionary significance of gene duplication on phenolic compound regulation.This paper functionally analyses the differences of two potato anthocyanin paralog MYB genes ScAN2 and ScAN1 and the response of the former to low temperatures. These are the major relevant aspects it underlines: (1) the historical evolution of ScAN2 and ScAN1, where ScAN2 retains the ability to be cold induced only in tolerant Solanum commersonii and not in sensitive Solanum tuberosum; (2) the different functionality of ScAN2 and its paralog ScAN1 to activate anthocyanins in a heterologous system; (3) the capacity of ScAN2 to activate hydroxycinnamic acid derivatives, important precursors of lignin and suberin production, and known compounds to face environmental stresses.