The unconventional resistance protein PTR recognizes the Magnaporthe oryzae effector AVR-Pita in an allele-specific manner
作者单位：State Key Laboratory of Hybrid RiceHunan Hybrid Rice Research Center International Rice Research Institute PHIM Plant Health Institute Univ.Montpellier INRAE CIRADInstitut Agro IRD College of Agronomy Hunan Agricultural University
会议名称：《第二十届中国作物学会学术年会》
会议日期：2023年
学科分类：09[农学] 0904[农学-植物保护] 090401[农学-植物病理学] 090402[农学-农业昆虫与害虫防治]
摘 要：Blast disease caused by the fungus Magnaporthe oryzae is one of the most devastating rice diseases. Disease resistance genes such as Pi-ta or Pi-ta2 are critical to protect rice production from blast. Published work reports that Pi-ta codes for a nucleotide-binding and leucine-rich repeat protein(NLR) that recognizes the fungal protease-like effector AVR-Pita by direct binding. However, this model was challenged by the recent discovery that Pi-ta2 resistance, which also relies on AVR-Pita detection, is conferred by the unconventional resistance gene Ptr, which codes for a membrane protein with a cytoplasmic armadillo repeat domain. Using NLR Pi-ta and Ptr RNAi knock-down and CRISPR/Cas9 knock-out mutant rice lines, we found that AVR-Pita recognition relies solely on Ptr and that the NLR Pi-ta has no role in it, indicating that it is not the Pi-ta resistance gene. Different alleles of Ptr confer different recognition specificities. The A allele of Ptr(PtrA) detects all natural sequence variants of the effector and confers Pi-ta2 resistance, while the B allele of Ptr(PtrB) recognizes a restricted set of AVR-Pita alleles and, thereby, confers Pi-ta resistance. Analysis of natural diversity in AVR-Pita and of mutant and transgenic strains identified one specific polymorphism in the effector sequence that controls escape from PtrB-mediated resistance. Taken together, our work establishes that the M. oryzae effector AVR-Pita is detected in an allele-specific manner by the unconventional rice resistance protein Ptr and that the NLR Pi-ta has no function in Pi-ta resistance and the recognition of AVR-Pita.