title: Pepper pectin methylesterase inhibitor protein CaPMEI1 is required for antifungal activity, basal disease resistance and abiotic stress tolerance.
abstract: Pectin is one of the main components of the plant cell wall that functions as the primary barrier against pathogens. Among the extracellular pectinolytic enzymes, pectin methylesterase (PME) demethylesterifies pectin, which is secreted into the cell wall in a highly methylesterified form. Here, we isolated and functionally characterized the pepper (Capsicum annuum L.) gene CaPMEI1, which encodes a pectin methylesterase inhibitor protein (PMEI), in pepper leaves infected by Xanthomonas campestris pv. vesicatoria (Xcv). CaPMEI1 transcripts are localized in the xylem of vascular bundles in leaf tissues, and pathogens and abiotic stresses can induce differential expression of this gene. Purified recombinant CaPMEI1 protein not only inhibits PME, but also exhibits antifungal activity against some plant pathogenic fungi. Virus-induced gene silencing of CaPMEI1 in pepper confers enhanced susceptibility to Xcv, accompanied by suppressed expression of some defense-related genes. Transgenic Arabidopsis CaPMEI1-overexpression lines exhibit enhanced resistance to Pseudomonas syringae pv. tomato, mannitol and methyl viologen, but not to the biotrophic pathogen Hyaloperonospora parasitica. Together, these results suggest that CaPMEI1, an antifungal protein, may be involved in basal disease resistance, as well as in drought and oxidative stress tolerance in plants.
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-ku, Seoul, 136-713, Republic of Korea.
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: An
authors.forename: Kee Hoon
authors.initials: KH
authors.lastname: Sohn
authors.forename: Hyong Woo
authors.initials: HW
authors.lastname: Choi
authors.forename: In Sun
authors.initials: IS
authors.lastname: Hwang
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Lee
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D000595:Amino Acid Sequence; D002212:Capsicum / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors; D055864:Droughts; D004591:Electrophoresis, Polyacrylamide Gel; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020868:Gene Silencing; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D044224:Pseudomonas syringae / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D016959:Xanthomonas campestris / Q000254:growth & development
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase