Activation of plant immune responses by a gain-of-function mutation in an atypical receptor-like kinase.
Arabidopsis (Arabidopsis thaliana) suppressor of npr1-1, constitutive1 (snc1) contains a gain-of-function mutation in a Toll/interleukin receptor-nucleotide binding site-leucine-rich repeat Resistance (R) protein and it has been a useful tool for dissecting R-protein-mediated immunity. Here we report the identification and characterization of snc4-1D, a semidominant mutant with snc1-like phenotypes. snc4-1D constitutively expresses defense marker genes PR1, PR2, and PDF1.2, and displays enhanced pathogen resistance. Map-based cloning of SNC4 revealed that it encodes an atypical receptor-like kinase with two predicted extracellular glycerophosphoryl diester phosphodiesterase domains. The snc4-1D mutation changes an alanine to threonine in the predicted cytoplasmic kinase domain. Wild-type plants transformed with the mutant snc4-1D gene displayed similar phenotypes as snc4-1D, suggesting that the mutation is a gain-of-function mutation. Epistasis analysis showed that NON-RACE-SPECIFIC DISEASE RESISTANCE1 is required for the snc4-1D mutant phenotypes. In addition, the snc4-1D mutant phenotypes are partially suppressed by knocking out MAP KINASE SUBSTRATE1, a positive defense regulator associated with MAP KINASE4. Furthermore, both the morphology and constitutive pathogen resistance of snc4-1D are partially suppressed by blocking jasmonic acid synthesis, suggesting that jasmonic acid plays an important role in snc4-1D-mediated resistance. Identification of snc4-1D provides us a unique genetic system for analyzing the signal transduction pathways downstream of receptor-like kinases.
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, China Agricultural University, Beijing 100094, People's Republic of China.
Dongling
D
Bi
Yu Ti
YT
Cheng
Xin
X
Li
Yuelin
Y
Zhang
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000378:metabolism; D004843:Epistasis, Genetic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; D011494:Protein Kinases