title: The pepper phosphoenolpyruvate carboxykinase CaPEPCK1 is involved in plant immunity against bacterial and oomycete pathogens.
abstract: Phosphoenolpyruvate carboxykinase, a member of the lyase family, is involved in the metabolic pathway of gluconeogenesis in organisms. Although the major function of PEPCK in gluconeogenesis is well established, it is unclear whether this enzyme is involved in plant immunity. Here, we isolated and identified the pepper (Capsicum annuum) PEPCK (CaPEPCK1) gene from pepper leaves infected with Xanthomonas campestris pv. vesicatoria (Xcv). CaPEPCK1 was strongly expressed in pepper leaves during the incompatible interaction with avirulent Xcv and in response to environmental stresses, especially salicylic acid (SA) treatment. PEPCK activity was low in healthy leaves but dramatically increased in avirulent Xcv-infected leaves. Knock-down expression of CaPEPCK1 by virus-induced gene silencing resulted in high levels of susceptibility to both virulent and avirulent Xcv infection. CaPEPCK1 silencing in pepper compromised induction of the basal defense-marker genes CaPR1 (pathogenesis-related 1 protein), CaPR10 (pathogenesis-related 10 protein) and CaDEF1 (defensin) during Xcv infection. SA accumulation was also significantly suppressed in the CaPEPCK1-silenced pepper leaves infected with Xcv. CaPEPCK1 in an Arabidopsis overexpression (OX) line inhibited the proliferation of Pseudomonas syringae pv. tomato (Pst) and Hyaloperonospora arabidopsidis (Hpa). CaPEPCK1-OX plants developed more rapidly, with enlarged leaves, compared to wild-type plants. The T-DNA insertion Arabidopsis orthologous mutants pck1-3 and pck1-4 were more susceptible to the bacterial Pst and oomycete Hpa pathogens than the wild type. Taken together, these results suggest that CaPEPCK positively contributes to plant innate immunity against hemibiotrophic bacterial and obligate biotrophic oomycete pathogens.
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Korea.|Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA, 92521, USA.
authors.forename: Du Seok
authors.initials: DS
authors.lastname: Choi
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Korea.|Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Nak Hyun
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Korea. bkhwang@korea.ac.kr.
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D002212:Capsicum / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D009868:Oomycetes; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D016959:Xanthomonas campestris
chemical_list: D019764:Phosphoenolpyruvate Carboxykinase (ATP)
keywords: Capsicum annuum; Microbial pathogens; Phosphoenolpyruvate carboxykinase; Plant defense; Xanthomonas campestris pv. vesicatoria