组蛋白去乙酰化酶参与番茄抗青枯病的分子机制

Tomato (Solanum lycopersicum L.), the second most consumed vegetable has been adopted as an important model plant. The productivity and quality of tomato fruits are often threatened by a broad range of plant diseases caused by fungi, bacteria, nematodes and arthropods. Ralstonia solanacearum is one of the most common soil borne vascular diseases of the tomato crop. Previously, fifteen HDACs were identified in tomato genome, most HDACs genes were up-regulated in response to R. solanacearum, and the histone H3 and H4 acetylation levels of defense related genes were also increased after treatment with R. solanacearum, over-expression lines of SlHDT3 improved defense of bacterial wilt and interact with SlWRKY80. In addition, TSA treatment enhanced resistance to bacterial wilt. However, up till now there is little knowledge about the involvement of histone modifications in resistance to bacterial wilt. In this study, we will focus on the functions of HDAC in bacterial wilt resistance. To further investigate the function of tomato HDAC in defense response, we will carry out experiments to analyze the defense mechanisms of histone acetylation with VIGS, Western-blot, ChIP and Q-PCR. Meanwhile, we will analyze the mechanisms of HDAC interacting proteins (such as transcription factor) in the process of bacterial wilt through Y2H, pull-down, BiFC and CoIP. Studies on how histone acetylation regulates defense response to bacterial wilt will contribute to our understanding of molecular mechanisms underlying the roles played by HDAC in tomato. This study will provide insights into epigenetic regulation in plant defense of bacterial wilt.

番茄是世界重要的经济作物和公认的模式植物之一，由茄科雷尔氏菌侵染番茄引起的青枯病是严重影响华南地区番茄生产的重要细菌性病害。前期研究发现青枯菌增加了番茄抗病基因的组蛋白H3和H4的乙酰化水平，TSA处理增强了番茄的抗青枯病能力，且发现SlHDT3转基因植株抗病性增强且与抗病基因SlWRKY80相互作用。然而植物体内组蛋白乙酰化水平的提高是通过何种途径提高番茄青枯病抗性，及组蛋白去乙酰化酶通过何种机制参与番茄抗青枯病还不清楚。本项目以番茄组蛋白去乙酰化酶为切入点，利用VIGS、Western-blot、ChIP、Q-PCR等技术研究番茄体内组蛋白乙酰化修饰与抗青枯病的关系；利用酵母双杂交、亲和层析纯化与质谱分析、BiFC、ChIP-target等方法筛选和鉴定组蛋白去乙酰化酶相互作用蛋白，以期阐明组蛋白乙酰化在番茄抗青枯病的分子调控途径，为利用基因工程手段改良番茄青枯病抗性奠定坚实的基础。

番茄是世界上重要的经济作物和模式植物之一，由茄科雷尔氏菌侵染番茄引起的青枯病是制约我国华南地区番茄生产的重要细菌性病害。本项目建立了番茄基因编辑和病毒诱导的基因沉默体系；通过载体构建和农杆菌介导的遗传转化，获得了番茄SlHDACs基因的过量表达和基因编辑株系；通过病毒诱导的基因沉默体系开展了番茄组蛋白去乙酰化酶参与番茄抗病机制研究，结果表明感病品种中与对照（100%）相比SlSRT2（54.17%）、SlHDA6（50.00%）基因沉默后降低了感病品种的发病率，利用QPCR和ChIP-QPCR分析了抗病通路基因的表达和乙酰化修饰，沉默SlHDACs主要通过提高了病基因的转录和乙酰化活性参与番茄抗青枯病；利用诱饵蛋白筛库，获得了96个WRKY转录因子、ERF转录因子、丝氨酸整合因子（SERINC）、以及纤维素合成酶等多个种类蛋白；并利用酵母双杂交和双分子荧光互补技术，首次揭示了具有乙酰化活性的青枯菌效应子蛋白PopP2通过与JA合成通路蛋白互作发挥抗病作用；同时利用苗期接种鉴定，系统分析了番茄抗青枯病资源，并将其按发病率分为5个类群；利用GWAS和Super-BSA技术获得了6号染色体的抗青枯病13个SNP位点。本项目的研究工作虽然进一步揭示了番茄组蛋白去乙酰化酶活性降低后提升了植株的抗病能力，然植物组蛋白乙酰化与具有乙酰化活性的青枯菌效应子蛋白PopP2的联系，以及通过何种机制调控抗病的机制还不清楚，但该研究结果为进一步揭示植物和青枯菌之间的互作机制提供了有益的线索。