AtMYB2在拟南芥与丁香假单胞菌互作中的作用及其与CBP60g的关系

Previous studies have shown that the Arabidopsis calmodulin-binding protein, CBP60g, was induced by the microbes associated molecular patterns and regulated salicylic acid accumulation. We found that CBP60g was ubiquitously expressed and localized to nuclei. Overexpression of CBP60g enhanced resistance of transgenic Arabidopsis to pathogen, while the cbp60g-1 mutant showed the contrary phenotype. In addition, the CBP60g overexpression lines exhibited hypersensitivity to abscisic acid treatment and increased tolerance to drought stress. By screening the expression profiles of the stress-related genes, we found that the mRNA level of one gene that encoding the transcription factor AtMYB2, has been changed obviously in both the CBP60g overexpression lines and the mutant cbp60g-1. It has been proved that AtMYB2 was involved in abiotic stress signaling before, and our evidence indicated that it might also contribute to disease resistance, and its role in disease resistance is linked with CBP60g. In this study, we try to reveal the function of AtMYB2 in disease resistance and its relationship with CBP60g in the cross-talk between disease and abiotic stess signaling pathways, and provide the theoretical supports for improving stress resistance ability of economic crops.

已有的研究表明，拟南芥钙调素结合蛋白CBP60g参与了对病原菌伴随分子模式的响应并调控水杨酸的积累。我们发现：CBP60g在拟南芥各组织中广泛表达，定位在细胞核中；CBP60g过表达植物对病原菌抗性增强，而突变体的表型与过表达相反；并且，CBP60g过表达植物对外源脱落酸处理更加敏感、对干旱的耐受能力增强。筛查胁迫条件下拟南芥基因表达谱发现，编码转录因子AtMYB2基因的mRNA水平在CBP60g过表达转基因植物和突变体中变化明显。前人的研究证实AtMYB2参与了植物对非生物胁迫的响应，我们的证据显示它可能也参与了植物抗病防卫反应，且与CBP60g有关。本研究旨在揭示拟南芥响应病原菌过程中AtMYB2的功能以及生物胁迫和非生物胁迫信号途径交叉中CBP60g与AtMYB2上、下游关系，为促进农作物抗逆能力的提高提供理论依据。

以拟南芥野生型、cbp60g-1突变体、CBP60g过表达株系、突变体和AtMYB2过表达株系为材料，研究了CBP60g在介导SA和ABA信号途径“对话 (cross-talk)”过程中与转录因子AtMYB2之间的相互关系，前期的研究表明，cbp60g-1突变体中AtMYB2表达有所降低，但是进一步的检测发现，Atmyb2突变体和AtMYB2过表达株系的抗病性与野生型相比并没有明显的变化（数据未发表）。在研究中，发现CBP60g过表达株系明显积累花青素，而cbp60g-1突变体则很少积，后续试验证明CBP60g作为花青素合成的负调控因子之一。同时，过表达CBP60g植株矮化、茎分支增多、主根生长缓慢且侧根增多，细胞内钙离子含量降低，对高浓度钙离子处理更加敏感， CAX1和CAX3的表达下调，Ca2+和IAA的运输受到影响。.本研究发表SCI收录论文2篇、出版专著1部、编写国际著作1章，发表中文核心期刊论文3篇，授权国家发明专利1项。培养博士研究生2名、硕士研究生4名，培训研究生13人次。项目负责人赴美国合作研究1人次3个月，赴英国约克大学高访研究1人次6个月。邀请国际本领域专家11人次来华交流合作。课题组成员参加国际学术会议6人次、国内学术会议16人次，举办国际学术论坛主会场1次、分会场4次。项目负责人入选省级人才工程一层次，获得国家级荣誉1次、省级荣誉称号2次，获得省级自然科学一等奖1项。团队入选3项省级科技创新团队，建设省级重点实验室1个。