转录因子DTF1调控稻瘟病抗性的分子机制

Rice blast caused by Magnaporthe oryzae (M. oryzae), is one of the devastating diseases of rice. Developing rice with resistance genes or resistance related genes is the most effective way to protect rice from this severe disease. Up to now, many genes conferring resistance have been explored. However, most of them mediate resistance with yield penalty. Therefore, it needs to explore novel resistant genes without yield penalty. We previously identified a natural Digu-specific SNP that is in the promoter of the transcription factor gene DTF1. The SNP resulted into that the expression of DTF1 in Digu was not induced, whereas the allele of DTF1 in the susceptible rice was up-regulated by M. oryzae significantly. Transgenic plants in silence or knocking out of DTF1 showed enhanced blast resistance without yield penalty, whereas the plants overexpressing DTF1 exhibited decrease resistance against M. oryzae, confirming the role of DTF1 in regulation of disease resistance. This study aims to identify the DTF1 interacting proteins (DIPs), and to verify the molecular regulations of these DIPs on blast resistance. Through this study, we will elucidate molecular mechanism of DTF1 on regulation of blast resistance and provide basic knowledge for breeding resistant rice.

稻瘟病严重危害水稻产量和品质。挖掘抗病基因及抗病相关基因并在育种中应用是减轻稻瘟病危害的有效方法。目前鉴定的稻瘟病抗性基因在提高抗性时，常伴有其它不良的农艺性状。我们在广谱持久抗稻瘟病的水稻材料地谷中编码一个转录因子基因DTF1的启动子区域，发现一个天然变异位点。该变异位点导致DTF1在地谷接菌后的表达量无显著变化，而在感病材料中则受菌诱导显著上调表达。感病水稻材料中基因DTF1表达受抑制或被敲除后，表现出稻瘟病抗性的增强，而主要农艺性状并不受显著影响。基于此，本项目拟通过分子生物学、生物化学及植物病理学等方法筛选转录因子DTF1的关键互作蛋白，并鉴定它们对稻瘟病抗性的调控作用，以此构建DTF1调控免疫反应的信号通路，从而阐述转录因子DTF1对稻瘟病抗性的分子调控机制，丰富稻瘟病抗病理论，并指导稻瘟病抗病育种。

稻瘟病严重危害水稻产量和品质。挖掘抗病基因及抗病相关基因并在育种中应用是减轻稻瘟病危害的最有效方法。目前鉴定的稻瘟病抗性基因在提高抗性时，常伴有其它不良的农艺性状。前期，我们在广谱持久抗稻瘟病的水稻材料地谷中编码一个转录因子基因DTF1的启动子区域，发现一个天然变异位点。该变异位点使水稻对稻瘟病的抗性增强，且不影响水稻的主要农艺性状。在本项目中，通过筛选和鉴定DTF1的互作蛋白，并验证其调控稻瘟病抗性的功能，以此构建DTF1调控免疫反应的信号网络。首先，通过Pull-down试验筛选到DTF1的互作蛋白。然后，利用酵母双杂交、双分子荧光互补（BiFC）等试验验证了DIP1和DIP2能够与DTF1互作。通过遗传转化获得DIP1和DIP2过量表达和敲除的转基因株系，并对其接种稻瘟病菌。发现DIP1过量表达或敲除均不能调控水稻对的稻瘟病的抗性，而DIP2敲除后增强了水稻对稻瘟病的抗性，而过量表达DIP2后，水稻更易感稻瘟病。表明DIP2负调控水稻对稻瘟病的抗性。该研究丰富了DTF1调控稻瘟病抗性的分子机制，并为稻瘟病抗病育种工作提供了候选基因。