title: Foliar application of the leaf-colonizing yeast Pseudozyma churashimaensis elicits systemic defense of pepper against bacterial and viral pathogens.
abstract: Yeast associates with many plant parts including the phyllosphere, where it is subject to harsh environmental conditions. Few studies have reported on biological control of foliar pathogens by yeast. Here, we newly isolated leaf-colonizing yeasts from leaves of field-grown pepper plants in a major pepper production area of South Korea. The yeast was isolated using semi-selective medium supplemented with rifampicin to inhibit bacterial growth and its disease control capacity against Xanthomonas axonopodis infection of pepper plants in the greenhouse was evaluated. Of 838 isolated yeasts, foliar spray of Pseudozyma churashimaensis strain RGJ1 at 108cfu/mL conferred significant protection against X. axonopodis and unexpectedly against Cucumber mosaic virus, Pepper mottle virus, Pepper mild mottle virus, and Broad bean wilt virus under field conditions. Direct antagonism between strain RGJ1 and X. axonopodis was not detected from co-culture assays, suggesting that disease is suppressed via induced resistance. Additional molecular analysis of the induced resistance marker genes Capsicum annuum Pathogenesis-Related (CaPR) 4 and CaPR5 indicated that strain RGJ1 elicited plant defense priming. To our knowledge, this study is the first report of plant protection against bacterial and viral pathogens mediated by a leaf-colonizing yeast and has potential for effective disease management in the field.
authors.affiliation: Molecular Phytobacteriology Laboratory, Superbacteria Research Center, KRIBB, Daejeon 305-806, South Korea.
authors.forename: Gahyung
authors.initials: G
authors.lastname: Lee
authors.affiliation: Microbial Resource Center, KRIBB, Jeongeup 56212, South Korea.|Department of Bioinformatics, University of Science and Technology (UST), Daejeon 34141, South Korea.
authors.forename: Sang-Heon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Microbial Resource Center, KRIBB, Jeongeup 56212, South Korea.|Department of Bioinformatics, University of Science and Technology (UST), Daejeon 34141, South Korea.
authors.forename: Kyung Mo
authors.initials: KM
authors.lastname: Kim
authors.affiliation: Molecular Phytobacteriology Laboratory, Superbacteria Research Center, KRIBB, Daejeon 305-806, South Korea.|Biosystems and Bioengineering Program, School of Science, University of Science and Technology (UST), Daejeon 34113, South Korea.
authors.forename: Choong-Min
authors.initials: CM
authors.lastname: Ryu
mesh_terms: D000898:Antibiosis; D002212:Capsicum / Q000276:immunology* / Q000382:microbiology*; D017799:Cucumovirus / Q000254:growth & development; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases / Q000517:prevention & control*; D018515:Plant Leaves / Q000276:immunology* / Q000382:microbiology*; D017800:Potyvirus / Q000254:growth & development; D056910:Republic of Korea; D017898:Tobamovirus / Q000254:growth & development; D014587:Ustilaginales / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D053532:Xanthomonas axonopodis / Q000254:growth & development