title: Constitutive expression of a fungus-inducible carboxylesterase improves disease resistance in transgenic pepper plants.
abstract: Resistance against anthracnose fungi was enhanced in transgenic pepper plants that accumulated high levels of a carboxylesterase, PepEST in anthracnose-susceptible fruits, with a concurrent induction of antioxidant enzymes and SA-dependent PR proteins. A pepper esterase gene (PepEST) is highly expressed during the incompatible interaction between ripe fruits of pepper (Capsicum annuum L.) and a hemibiotrophic anthracnose fungus (Colletotrichum gloeosporioides). In this study, we found that exogenous application of recombinant PepEST protein on the surface of the unripe pepper fruits led to a potentiated state for disease resistance in the fruits, including generation of hydrogen peroxide and expression of pathogenesis-related (PR) genes that encode mostly small proteins with antimicrobial activity. To elucidate the role of PepEST in plant defense, we further developed transgenic pepper plants overexpressing PepEST under the control of CaMV 35S promoter. Molecular analysis confirmed the establishment of three independent transgenic lines carrying single copy of transgenes. The level of PepEST protein was estimated to be approximately 0.002 % of total soluble protein in transgenic fruits. In response to the anthracnose fungus, the transgenic fruits displayed higher expression of PR genes, PR3, PR5, PR10, and PepThi, than non-transgenic control fruits did. Moreover, immunolocalization results showed concurrent localization of ascorbate peroxidase (APX) and PR3 proteins, along with the PepEST protein, in the infected region of transgenic fruits. Disease rate analysis revealed significantly low occurrence of anthracnose disease in the transgenic fruits, approximately 30 % of that in non-transgenic fruits. Furthermore, the transgenic plants also exhibited resistance against C. acutatum and C. coccodes. Collectively, our results suggest that overexpression of PepEST in pepper confers enhanced resistance against the anthracnose fungi by activating the defense signaling pathways.
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Moonkyung
authors.initials: M
authors.lastname: Ko
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Hyo-Hyoun
authors.initials: HH
authors.lastname: Seo
authors.affiliation: Department of Biology, Chosun University, Gwangju, 501-759, Republic of Korea.
authors.forename: Hyun-Hwa
authors.initials: HH
authors.lastname: Lee
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Ha-Young
authors.initials: HY
authors.lastname: Kang
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Thai Son
authors.initials: TS
authors.lastname: Nguyen
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Hyun Cheol
authors.initials: HC
authors.lastname: Soh
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea. youngskim@chonnam.ac.kr.
authors.forename: Young Soon
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju, 500-757, Republic of Korea. kimji@chonnam.ac.kr.
authors.forename: Jeong-Il
authors.initials: JI
authors.lastname: Kim
mesh_terms: D002212:Capsicum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D043182:Carboxylesterase / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D020231:Colletotrichum / Q000502:physiology*; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics*; D054884:Host-Pathogen Interactions / Q000235:genetics; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000382:microbiology; D014170:Transformation, Genetic
chemical_list: D043182:Carboxylesterase
keywords: Anthracnose; Colletotrichum gloeosporioides; Pathogenesis related; PepEST; Pepper esterase