小麦抗白粉病新型mlo突变体的研究及应用

Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the most destructive disease in wheat worldwide. Breeding of wheat varieties with durable and broad-spectrum powdery mildew resistance is urgently needed, but still a challenge. The negative regulatory role of MLO (mildew resistance locus o) genes in plant immunity is evolutionarily conserved in higher plant species. Loss-of-function mutant alleles of the MLO genes confer durable and broad-spectrum resistance to the powdery mildew fungal pathogens in various plant species. We have previously demonstrated that TALEN-induced mutation of all three TaMLO homoeologs in hexaploid bread wheat confers heritable broad-spectrum resistance to powdery mildew. However, adverse effects of the mlo mutation, mainly premature leaf senescence limit the use of mlo mutants in breeding programs. This work is based on a newly isolated wheat mlo mutant that demonstrates strong resistance to powdery mildew, but no premature leaf senescence. The proposed study will focus on: 1) identification of the genetic changes in the novel mlo mutant and understanding the mechanisms regulating the expression of wheat MLO genes; 2) generation of more similar mlo mutants and application of these mutants in wheat resistance breeding. The proposed research will lead to new insights into the broad-spectrum powdery-mildew resistance and new wheat varieties with durable and broad-spectrum powdery-mildew resistance, while providing new strategies and technologies for disease resistance improvement in other crops.

白粉病是小麦主要病害之一，培育具广谱、持久抗性的品种是当前小麦抗白粉病育种的重要任务和挑战。MLO基因进化上高度保守，其突变植物表现出对白粉菌广谱、持久的抗性。我们前期利用基因组编辑技术对六倍体小麦中MLO基因的三个拷贝同时进行了突变，获得了对白粉病具有广谱抗性的小麦材料。然而，mlo突变体的早衰表型限制了其在生产上的应用。本项目从最新获得的抗白粉病、但不早衰的小麦mlo新型突变体入手，研究该突变体的突变位点及MLO基因的表达调控机制，在此基础上，获得更多mlo新型突变体并进行抗病育种。本工作的开展将加深对白粉病广谱抗性分子基础的了解，创制具广谱、持久白粉病抗性的小麦新种质，同时为其它作物抗白粉病育种提供思路和借鉴。

白粉病是小麦最重要的真菌病害，病害高发时减产可达50%。培育广谱、持久抗性的品种是当前小麦抗白粉病育种的重要任务和挑战。MLO基因进化上高度保守，其突变植物表现出对相应白粉菌广谱、持久的抗性。我们前期利用基因组编辑技术对六倍体小麦中MLO基因的三个拷贝同时进行了突变，获得了对白粉病具有广谱抗性的小麦材料。然而，mlo突变体的早衰表型限制了其在生产上的应用。本研究从我们获得的既抗白粉菌又不早衰的新型mlo突变体入手，重点鉴定该突变体的突变方式，并研究了该基因与MLO基因的遗传互作，在此基础上，解析了MLO新型调控机制。我们也通过基因组编辑产生了多个类似的mlo突变体，并将它们用于小麦抗病育种。取得的主要成果如下：.1）阐明了新型突变体材料R32具有抗病增产的表型；.2）鉴定了R32突变体的突变方式并分析了其表型产生的分子机理；.3）开发了新型高效的基因组编辑工具，并应用于小麦抗病材料的创制；.4）利用突变体初步开展了广谱持久抗白粉病小麦育种工作。.已顺利完成研究内容及任务，研究结果加深了我们对白粉病广谱抗性分子基础的了解，为创制具广谱、持久白粉病抗性的小麦新种质，同时也为其它作物抗白粉病育种提供思路和借鉴。