Plant Journal | 沈阳农大纪淑娟团队揭示CaMYB340转录因子通过抑制脂肪酸去饱和诱导采后甜椒冷害

今天介绍的是沈阳农大纪淑娟团队在Plant J发表的研究论文《The CaMYB340 transcription factor induces chilling injury in post-harvest bell pepper by inhibiting fatty acid desaturation》。

甜椒是一种重要的商业化的园艺作物；然而，其易腐烂的性质需要低温处理。 但矛盾的是，寒冷会导致冷害 (CI) 和收获后的浪费。 

目前关于辣椒中CI的知识是有限的。CI的机制是多方面的。因此，作者专注于脂肪酸（FA）去饱和开展系列研究。 

作者鉴定了上游核转录因子CaMYB340（属于R2R3 MYB亚家族），负调控 FA去饱和和CaCBF3表达，其基因和蛋白质表达受低温诱导。

具体而言，McrBC处理和亚硫酸氢盐测序PCR表明，暴露于寒冷会触发 CaMYB340启动子中CHH位点之一上的DNA甲基化。这种表观遗传事件至少部分促成了CaMYB340转录水平的上调。CaMYB340 表达增加导致与 CabHLH93和CaMYB1R1形成蛋白质复合物，进而下调下游基因的表达。 

对于低温保存的辣椒，CaMYB340 的瞬时过表达会降低不饱和FA 含量和膜流动性，导致冷诱导的果皮质地变差。瞬时CaMYB340沉默增加了FA去饱和度并降低了电解质泄漏，增强了CaMYB340敲减的辣椒的耐寒性。

总体而言，这些结果强调了植物转录网络的复杂性，并突出了CaMYB340在辣椒果实CI发生中的作用。

Bell pepper (Capsicum annuum L.) is a tradable and desirable crop; however, its perishable nature requires low-temperature handling. Paradoxically, cold causes chilling injury (CI) and post-harvest waste. Current knowledge about CI in pepper is limited. The mechanism of CI is multi-faceted; therefore, we focused on fatty acid (FA) desaturation. We identified an upstream nuclear transcription factor (TF), CaMYB340, belonging to the R2R3 MYB subfamily, that negatively regulates FA desaturation and CaCBF3 expression and whose gene and protein expression is induced by low temperature (4°C). Specifically, McrBC treatment and bisulfite sequencing PCR indicate that exposure to cold triggers DNA methylation on one of the CHH sites in the CaMYB340 promoter. This epigenetic event at least partly contributes to the upregulation of CaMYB340 transcript levels. Increased expression of CaMYB340 results in the formation of protein complexes with CabHLH93 and CaMYB1R1, which in turn downregulate the expression of downstream genes. For peppers held at low temperature, transient overexpression of CaMYB340 reduced unsaturated FA content and membrane fluidity, resulting in cold-induced poor peel texture. Transient CaMYB340 silencing increased FA desaturation and lowered electrolyte leakage, enhancing cold tolerance in CaMYB340 knockdown fruits. Overall, these results underscore the intricacy of transcriptional networks in plants and highlight the role of CaMYB340 in CI occurrence in pepper fruits.

转自：植物生物技术Pbj

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