A novel pepper (Capsicum annuum) receptor-like kinase functions as a negative regulator of plant cell death via accumulation of superoxide anions.
Plant receptor-like kinases belong to a large gene family. The Capsicum annuum receptor-like kinase 1 (CaRLK1) gene encodes a transmembrane protein with a cytoplasmic kinase domain and an extracellular domain. The CaRLK1 extracellular domain (ECD)-green fluorescent protein (GFP) fusion protein was targeted to the plasma membrane, and the kinase domain of the CaRLK1 protein exhibited autophosphorylation activity. CaRLK1 transcripts were more strongly induced in treatment with Xag8ra than in treatment with Xag8-13. Furthermore, infection with incompatible Xanthomonas campestris pv. vesicatoria race 3 induced expression of CaRLK1 more strongly than in the compatible interaction. Cell death caused by both a disease-forming and an HR-inducing pathogen was delayed in the CaRLK1-transgenic plants. Ectopic expression of CaRLK1 also induced transcripts of the lesion stimulating disease (LSD) gene, a negative regulator of cell death. Respiratory burst oxidase homolog (RBOH) genes were up-regulated in the transgenic plants compared with the wild type, as the concentration of the superoxide anion was increased. In contrast, the concentration of H(2)O(2) did not differ between the transgenic and wild-type plants. These results support the theory that the suppression of plant cell death by CaRLK1 is associated with consistent production of the superoxide anion and induction of the RBOH genes and the LSD gene, but not with the concentration of H(2)O(2). Thus, CaRLK1 may be a receptor of an as yet unidentified pathogen molecular pattern and may function as a negative regulator of plant cell death.
Yi
So Y
SY
Plant System Engineering Research Center, KRIBB, Daejon 305-600, Korea.
Lee
Dong J
DJ
Yeom
Seon-In
SI
Yoon
Joonseon
J
Kim
Yun-Hee
YH
Kwon
Suk-Yoon
SY
Choi
Doil
D
D000595:Amino Acid Sequence; D000975:Antioxidants / Q000378:metabolism; D002212:Capsicum / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D016923:Cell Death / Q000187:drug effects; D003067:Coenzymes / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008345:Manganese / Q000378:metabolism; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D021381:Protein Transport / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D013481:Superoxides / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D016959:Xanthomonas campestris / Q000187:drug effects
D000975:Antioxidants; D003067:Coenzymes; D018076:DNA, Complementary; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D013481:Superoxides; D008345:Manganese; D006861:Hydrogen Peroxide; D010770:Phosphotransferases