PtrMYC2-PtrBADH分子模块调控枳（Poncirus trifoliata）甜菜碱积累应答低温胁迫的分子机制解析

甜菜碱醛脱氢酶（BADH）介导的甘氨酸甜菜碱（GB）在植物逆境应答中起重要作用。我们利用柑橘抗寒资源枳（Poncirus trifoliata）低温表达谱鉴定了PtrBADH 基因，通过酵母单杂交筛选到JA信号途径转录因子PtrMYC2，但PtrMYC2-PtrBADH模块及JA信号调控GB积累参与枳低温应答的分子机制不清楚。本项目将分析PtrMYC2启动子低温应答特征并鉴定其关键元件，阐明PtrMYC2对PtrBADH启动子的调控机制，鉴定低温和MeJA应答最显著的枳JAZ蛋白（PtrJAZx），分析低温与JA对PtrJAZx与PtrMYC2互作的影响，揭示PtrJAZx及PtrMYC2协同调控PtrBADH应答低温与JA及介导GB积累的机制及其抗寒功能。本项目既揭示枳PtrBADH响应低温与GB积累的分子调控网络，也为柑橘抗寒基因工程提供关键基因，因而具有重要科学意义和潜在应用价值。

Glycine betaine (GB) systhesized via BADH (betaine aldehyde dehydrogenase) catalysis plays a crucial role in abiotic stress response in higher plants. a BADH gene, designated as PtrBADH, that was cold-inducible has been explored using an expression profile of Poncirus trifoliata, a cold-hardy germplam related to citrus, following cold treatment. In addition, a MYC2 transcription factor (named as PtrMYC2), a critical member implicated in the JA signal pathway was fished out based on yeast one-hybrid screening. Nevertheless, the molecular mechanisms concerning regulation of GB accumulation and cold response of Poncirus trifoliata by the PtrMYC2-PtrBADH module and JA signaling remain unclear. In order to anwser these questions, in the present project expression patterns of PtrMYC2 promoter in response to cold treatmetn will be analzyed, and elements on the promoter necessary for the response will be determined. Regulatory mechanism of PtrBADH promoter by PtrMYC2 will be examined. A JAZ protein (desginated as PtrJAZx), an important component member of JA signialing pathway, that is mostly responsvie to cold and MeJA treatment will be identified in Poncirus trifoliata. Interaction between PtrJAZx and PtrMYC2 in the presence or absence of cold and MeJA will be assessed. Synergistic regulation of PtrBADH’s response to cold and MeJA treatment and GB accumulation by PtrJAZx and PtrMYC2 will be elucidated. Besides, their functions in cold tolerance will be deciphered. The current work is expected to reveal molecular regulatory network on PtrBADH and GB accumulation in response to cold stress, and to provide critical genes for cold tolerance-oriented genetic engineering, underpining the scientific significance and potential application of this project.