拟南芥AtLBD15 通过参与ABA信号通路调控植物干旱胁迫的分子机理研究

Drought is a central abiotic stress for agricultural crops. AtLBD15 is one member of Arabidopsis LATERAL ORGAN BOUNDARIES DOMAIN (LBD) genes family, which encode plant-specific nuclear proteins containing the conserved domain LATERAL ORGAN BOUNDARIES (LOB). Our preliminary studies showed the lbd15 display a reduced sensitivity to ABA in both seed germinatin and root growth, and decreases drought tolerance. Two putative targeted genes ( ABI3 and ABI4 ) were found via Genome-wide chromatin immunoprecipitation (ChIP–chip) assay. Thus, we speculated that AtLBD15 might be involved in ABA signaling and play a role in plant drought stress. Experiments using ChIP-on-PCR and EMSA (Gel-shift) will be performed to demonstrate AtLBD15 specific binding promoter element of targeted genes. Gain-of-function and loss-of-function mutants and double mutants as the materials, will be used to verify that AtLBD15 functions in ABA signaling and drought tolerance. Domain swap experiments of LBD15 promoter and coding domain will reveal that some regulatory regions of LBD15 promoter are response for ABA and drought stress, and which coding sequences are function in ABA signaling and drought tolerance. The results of this project will be helpful for us to further understand ABA signaling pathway and provide theoretical basis to understand molecular mechanism of pant drought resistance.

干旱胁迫是制约作物产量的最重要因素之一。AtLBD15是拟南芥LBD转录因子家族的一个成员。项目申请人前期研究中发现AtLBD15缺失突变体具有ABA不敏感表型，且对干旱胁迫的耐受性明显降低。通过染色质免疫共沉淀结合芯片技术发现其可能通过ABA通路上的ABI3和ABI4参与ABA信号通路。本研究拟通过ChIP-on-PCR和EMSA确定LBD15在ABA信号通路上的靶基因的结合位点，分析LBD15缺失和过表达植株以及与abi3、abi4双杂交植株对ABA的应答反应和抗旱反应，进一步明确该基因在植物抗旱中的作用。利用启动子调控域替换和编码区功能域替换技术，明确LBD15调控域和功能域各部分在ABA信号通路和干旱胁迫中功能。本项目的研究结果为进一步丰富ABA信号通路和增强对植物抗逆境胁迫的分子机制的了解提供理论基础。

干旱是影响植物生长和发育的主要环境因子之一，阐明植物耐旱的分子机理有利于利用生物技术改良农作物，提高作物参量。本研究在前期工作的基础上提出拟南芥LBD15通过参与ABA信号通路调控植物的干旱胁迫。为了进一步研究LBD15在ABA信号通路中的作用机制，我们将lbd15缺失突变体和LBD15过表达株系进行了ABA和干旱处理，以及失水率和气孔观察，确定了LBD15在干旱胁迫中的功能。构建了AtLBD15启动子表达载体及删除可能ABA响应元件的启动子表达载体，对它们响应ABA处理做了验证。对LBD15各功能域替换发现，LBD15的In区对LBD15的功能具有不可替代的作用。利用qRT-PCR分析了下游可能的靶基因发现ABI3和ABI4在过表达植株的表达量上调明显。通过杂交获得了lbd15分别与abi3和abi4的双突变体，分析了其在ABA处理中的表型，确立了它们之间的遗传关系。目前，我们已经发表3篇标注本项目资助的相关论文，同时正在整理相关实验数据，并撰写论文，希望很快发表。本项目的研究结果丰富了干旱胁迫下ABA信号通路，增强了对植物抗旱胁迫分子机理的了解。