Nucleotide-binding leucine-rich repeat (NLR) immune receptors that recognize pathogen effectors and activate effector-triggered immunity (ETI) are a class of immune receptors widely present in plants. Most cloned resistance genes in plants belong to this type.
Recently, a team led by Prof. LIU Zhiyong at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, in collaboration with the team led by Prof. LI Hongjie at the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences and Dr. GU Yongqiang at the Agricultural Research Service of the U.S. Department of Agriculture (USDA-ARS) West Regional Research Center, USA, identified a rare gain of function mutation in a NLR that confers resistance to wheat powdery mildew, one of the most widely epidemic diseases in wheat.
Using the map-based cloning approach, the powdery mildew resistance gene Pm5e was characterized in Chinese wheat Fuzhuang 30. Pm5e encodes a typical NLR protein and the powdery mildew resistance function was validated by independent EMS mutants and transgenic assay.
Allelic variation and haplotype analysis of the worldwide diversified wheat germplasms revealed that the rare nonsynonymous single nucleotide variant (SNV) c.G3033A (corresponding to the amino acid p.M1011I) within the C-terminal leucine rich repeat (LRR) domain is responsible for the gain of powdery mildew resistance function of Pm5e, an allele endemic to wheat landraces of Shaanxi province of China, indicating that landraces can provide valuable genetic resources for crop genetic improvement.
Fuzhuang 30 (Pm5e) is a pure line cultivar re-selected from the wheat cultivar Jinghui 30. Jinghui 30 and Fuzhuang 30 were widely cultivated in the Guanzhong Plain, a lower valley of the Wei River in Shaanxi province, China, during the 1940s - 1970s.
At present, they still exhibit resistance to 82.2% of the Bgt isolates tested, strongly indicating that Pm5e confers durable and broad-spectrum powdery mildew resistance.
The cloning of Pm5e and the identification of the rare c.G3033A SNV provide a valuable genetic resource for molecular design and precise genome editing breeding of wheat powdery mildew resistance.
The research was supported by the State Transgenic Research Project, the National Natural Science Foundation of China, and the Science and Technology Service Network Initiative of the Chinese Academy of Sciences.
