title: A Pectate Lyase-Coding Gene Abundantly Expressed during Early Stages of Infection Is Required for Full Virulence in Alternaria brassicicola.
abstract: Alternaria brassicicola causes black spot disease of Brassica species. The functional importance of pectin digestion enzymes and unidentified phytotoxins in fungal pathogenesis has been suspected but not verified in A. brassicicola. The fungal transcription factor AbPf2 is essential for pathogenicity and induces 106 genes during early pathogenesis, including the pectate lyase-coding gene, PL1332. The aim of this study was to test the importance and roles of PL1332 in pathogenesis. We generated deletion strains of the PL1332 gene, produced heterologous PL1332 proteins, and evaluated their association with virulence. Deletion strains of the PL1332 gene were approximately 30% less virulent than wild-type A. brassicicola, without showing differences in colony expansion on solid media and mycelial growth in nutrient-rich liquid media or minimal media with pectins as a major carbon source. Heterologous PL1332 expressed as fusion proteins digested polygalacturons in vitro. When the fusion proteins were injected into the apoplast between leaf veins of host plants the tissues turned dark brown and soft, resembling necrotic leaf tissue. The PL1332 gene was the first example identified as a general toxin-coding gene and virulence factor among the 106 genes regulated by the transcription factor, AbPf2. It was also the first gene to have its functions investigated among the 19 pectate lyase genes and several hundred putative cell-wall degrading enzymes in A. brassicicola. These results further support the importance of the AbPf2 gene as a key pathogenesis regulator and possible target for agrochemical development.
authors.affiliation: Incurable Diseases Research Center (WCI), Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Yangrae
authors.initials: Y
authors.lastname: Cho
authors.affiliation: Chemical Biology Research Center, Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea; Department of Bio Health Science, Changwon National University, Uichang-gu, Changwon-si, Gyeongsangnam-do, 641-773, Republic of Korea.
authors.forename: Mina
authors.initials: M
authors.lastname: Jang
authors.affiliation: Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK, 73104, United States of America.
authors.forename: Akhil
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: Chemical Biology Research Center, Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Jae-Hyuk
authors.initials: JH
authors.lastname: Jang
authors.affiliation: Incurable Diseases Research Center (WCI), Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Nak-Kyun
authors.initials: NK
authors.lastname: Soung
authors.affiliation: Chemical Biology Research Center, Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Sung-Kyun
authors.initials: SK
authors.lastname: Ko
authors.affiliation: Department of Bio Health Science, Changwon National University, Uichang-gu, Changwon-si, Gyeongsangnam-do, 641-773, Republic of Korea.
authors.forename: Dae-Ook
authors.initials: DO
authors.lastname: Kang
authors.affiliation: Chemical Biology Research Center, Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Jong Seog
authors.initials: JS
authors.lastname: Ahn
authors.affiliation: Incurable Diseases Research Center (WCI), Bio-Therapeutics Research Institute, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk, 363-883, Republic of Korea.
authors.forename: Bo Yeon
authors.initials: BY
authors.lastname: Kim
mesh_terms: D000528:Alternaria / Q000235:genetics* / Q000472:pathogenicity*; D001937:Brassica / Q000382:microbiology; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D009336:Necrosis / Q000235:genetics; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D011133:Polysaccharide-Lyases / Q000235:genetics*; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D011133:Polysaccharide-Lyases; C023911:pectate lyase