The JA-responsive MYC2-BADH-like transcriptional regulatory module in Poncirus trifoliata contributes to cold tolerance by modulation of glycine betaine biosynthesis
The JA-responsive MYC2-BADH-like transcriptional regulatory module in Poncirus trifoliata contributes to cold tolerance by modulation of glycine betaine biosynthesis
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DOI：
10.1111/nph.17063
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发表时间：
2020-12-19
期刊：
影响因子：
9.4
通讯作者：
Liu, Ji-Hong
中科院分区：
文献类型：
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作者：
Ming, Ruhong;Zhang, Yang;Liu, Ji-Hong
甜菜碱（Glycine betaine，GB）在低温胁迫下会大量积累，但其分子机制和调控网络尚不清楚，我们证明了枳壳PtrMYC 2通过直接调控PtrBADH-1，PtrBADH-1是一个类似甜菜碱醛脱氢酶（BADH）的基因，通过转录组和表达分析，在三叶草中鉴定出PtrBADH-1。过表达和VIGS（virus-induced gene silencing）介导的敲低表明PtrBADH-1在抗寒性和GB合成中起积极作用。使用PtrBADH-1启动子作为诱饵的酵母单杂交文库筛选揭示了PtrMYC 2作为相互作用候选物。PtrMYC 2被证实直接结合到PtrBADH-1启动子内的两个G-box顺式作用元件，并作为转录激活因子。此外，PtrMYC 2通过调节PtrBADH-1的表达来调节GB合成，从而在耐冷性中发挥积极作用。有趣的是，我们发现冷胁迫下GB的积累是JA依赖的，并且PtrMYC 2协调JA介导的PtrBADH-1上调和GB积累。特别是，我们提出了一个转录调控模块PtrMYC 2-PtrBADH-1，以促进了解低温胁迫下GB积累的分子机制。
Glycine betaine (GB) is known to accumulate in plants exposed to cold, but the underlying molecular mechanisms and associated regulatory network remain unclear.Here, we demonstrated that PtrMYC2 of Poncirus trifoliata integrates the jasmonic acid (JA) signal to modulate cold-induced GB accumulation by directly regulating PtrBADH-l, a betaine aldehyde dehydrogenase (BADH)-like gene.PtrBADH-l was identified based on transcriptome and expression analysis in P. trifoliata. Overexpression and VIGS (virus-induced gene silencing)-mediated knockdown showed that PtrBADH-l plays a positive role in cold tolerance and GB synthesis. Yeast one-hybrid library screening using PtrBADH-l promoter as baits unraveled PtrMYC2 as an interacting candidate. PtrMYC2 was confirmed to directly bind to two G-box cis-acting elements within PtrBADH-l promoter and acts as a transcriptional activator. In addition, PtrMYC2 functions positively in cold tolerance through modulation of GB synthesis by regulating PtrBADH-l expression. Interestingly, we found that GB accumulation under cold stress was JA-dependent and that PtrMYC2 orchestrates JA-mediated PtrBADH-l upregulation and GB accumulation.This study sheds new light on the roles of MYC2 homolog in modulating GB synthesis. In particular, we propose a transcriptional regulatory module PtrMYC2-PtrBADH-l to advance the understanding of molecular mechanisms underlying the GB accumulation under cold stress.