MiR858靶向myb基因调控孑遗植物蒙古沙冬青干旱胁迫应答的机理

Ammopiptanthus mongolicus, a relic plant and one of the only two broadleaf evergreen shrubs in desert and arid region in Northwest China, exhibits a high level tolerance to drought stresses, being regarded as an important resource plant for mining stress-tolerant genes. miRNAs play key roles in abiotic stress response in plant, thus investigating the roles of miRNAs and their targets in stress adaptation will advance our understanding on the molecular mechanism underlying the stress tolerance of A. mongolicus. The applicants systematically identified the miRNAs in A. mongolicus and determined several novel drought-responsive miRNAs including Amo-miR858. Based on these results, the applicants plan to investigate the molecular regulation network of responses to drought stress mediated by Amo-miR858-targeted myb transcription factors. First, the spatial and temporal gene expression pattern and stress and hormones induced gene expression pattern of Amo-miR858 are monitored using the stem-loop qRT-PCR technology. The target genes are systematically identified by degradome sequencing and miRNA and target gene co-transformation technology. The downstream genes of representative myb targets are determined through chromatin immunoprecipitation of transcription factors followed by sequencing. Finally, the functions of these representative myb targets in stress tolerance are revealed by analyzing the effect of their ectopic over-expression on secondary metabolite pathways and other biological processes. The study will conduct research centering around the main line “miRNA→transcription factors→secondary metabolite pathway”, and will advance our understanding on the molecular mechanism underlying the regulation of secondary metabolites under stressful conditions, and provide important data for gene resource evaluation in A. mongolicus.

孑遗植物蒙古沙冬青是我国西北荒漠地区罕见的常绿旱生灌木，对干旱环境具有较强的耐受性，是重要的抗逆基因资源植物。miRNA在植物逆境响应中发挥重要作用，研究蒙古沙冬青miRNA及其靶基因在逆境应答中的作用，有助于从分子水平上理解该植物的耐逆机理。在申请者系统鉴定蒙古沙冬青miRNA，发现Amo-miR858等新的干旱响应miRNA的基础上，本项目拟进一步研究Amo-miR858靶向myb转录因子调控蒙古沙冬青干旱胁迫应答的分子机理。首先分析Amo-miR858的时空和诱导表达特征，鉴定Amo-miR858的靶基因及其调控的下游基因，然后通过植物转基因研究myb靶基因如何通过调控黄酮类次生代谢产物途径等生物学过程，参与干旱应答。本项目以miRNA→转录因子→次生代谢产物为主线开展相关研究，有助于加深逆境对于植物次生代谢产物途径的调控机理的认识，并可为孑遗植物蒙古沙冬青的基因资源评价提供依据。

孑遗植物蒙古沙冬青是我国西北荒漠地区罕见的常绿旱生灌木，对干旱环境具有较强的耐受性，是重要的抗逆基因资源植物。miRNA在植物生长发育和逆境应答中发挥重要的调控作用，研究蒙古沙冬青miRNA及其靶基因在逆境应答中的作用，有助于从分子水平上理解沙冬青的耐逆机理。本研究主要应用生理生化、分子生物学和组学研究手段，以及植物转基因技术，分析了沙冬青miR858的时空和诱导表达特征，系统鉴定沙冬青miR858的靶基因及其调控的下游基因，然后通过植物转基因分析了几个miR858的代表性myb靶基因如何通过调控黄酮类次生代谢产物途径等生物学过程，参与干旱应答。基于研究结果，构建应答干旱逆境的(miR858) → (myb) → (myb 下游基因)的多级分子调控网络模型，揭示miR858 介导 myb 类转录因子调控蒙古沙冬青干旱应答的分子机理。本项目有助于加深对于植物逆境应答分子机制的认识，并可为孑遗植物蒙古沙冬青的基因资源评价提供依据。本研究将促进对于荒漠孑遗植物沙冬青的认识和保护，提高其社会影响，所获得的调控沙冬青耐逆性的myb转录因子基因具有一定的应用价值。