srfr1 negatively regulates plant nb-lrr resistance protein accumulation to prevent autoimmunitysrfr1消极预防自身免疫调节植物nb-lrr抵抗蛋白质积累.pdfVIP

SRFR1 Negatively Regulates Plant NB-LRR Resistance Protein Accumulation to Prevent Autoimmunity 1,2 1 1 3 3 1 Yingzhong Li , Shuxin Li , Dongling Bi , Yu Ti Cheng , Xin Li , Yuelin Zhang * 1 National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing, People’s Republic of China, 2 College of Life Sciences, Peking University, Beijing, People’s Republic of China, 3 Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada Abstract Plant defense responses need to be tightly regulated to prevent auto-immunity, which is detrimental to growth and development. To identify negative regulators of Resistance (R) protein-mediated resistance, we screened for mutants with constitutive defense responses in the npr1-1 background. Map-based cloning revealed that one of the mutant genes encodes a conserved TPR domain-containing protein previously known as SRFR1 (SUPPRESSOR OF rps4-RLD). The constitutive defense responses in the srfr1 mutants in Col-0 background are suppressed by mutations in SNC1, which encodes a TIR-NB-LRR (Toll Interleukin1 Receptor-Nucleotide Binding-Leu-Rich Repeat) R protein. Yeast two-hybrid screens identified SGT1a and SGT1b as interacting proteins of SRFR1. The interactions between SGT1 and SRFR1 were further confirmed by co-immunoprecipitation analysis. In srfr1 mutants, levels of multiple NB-LRR R proteins including SNC1, RPS2 and RPS4 are increased. Increased accumulation of SNC1 is also observed in the sgt1b mutant. Our data suggest that SRFR1 functions together with SGT1 to negatively regulate R protein accumulation, which is required for preventing auto-