title: Isolation and characterization of endophytic actinomycetes from Chinese cabbage roots as antagonists to Plasmodiophora brassicae.
abstract: This study was conducted to select endophytic actinomycetes as biocontrol agents against Chinese cabbage clubroot caused by Plasmodiophora brassicae. A total of 81 endophytic actinomycetes were isolated from surface-sterilized roots of Chinese cabbage that was grown on paddy field and upland soils collected from various locations in Korea. By using 16S ribosomal DNA (rDNA) gene sequencing, they were classified to 8 actinobacterial genera. The genus Microbispora (67%) was most frequently isolated, followed by Streptomyces (12%) and Micromonospora (11%). Three of the 81 isolates, when inoculated in germinated Chinese cabbage seeds and then transplanted to pots, effectively suppressed the occurrence of a post-inoculated strain of P. brassicae in the pots. They showed control values of 58% for strain A004, 33% for strain A004, and 42% for strain A018. Based on cell wall components, morphological characteristics, and phylogenetic analyses, the three antagonistic isolates were identified as Microbispora rosea subsp. rosea (A004 and A011) and Streptomyces olivochromogenes (A018). Further researches on the field efficacy and action modes of the three actinomycetes are in progress.
authors.affiliation: Bio-Control Research Team, Chemical Biotechnology Research Center, Korea Research Institute of Chemical Technology, Daejeon 305-600, Korea.
authors.forename: Sun Og
authors.initials: SO
authors.lastname: Lee
authors.forename: Gyung Ja
authors.initials: GJ
authors.lastname: Choi
authors.forename: Yong Ho
authors.initials: YH
authors.lastname: Choi
authors.forename: Kyoung Soo
authors.initials: KS
authors.lastname: Jang
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Park
authors.forename: Chang Jin
authors.initials: CJ
authors.lastname: Kim
authors.forename: Jin-Cheol
authors.initials: JC
authors.lastname: Kim
mesh_terms: D000192:Actinomycetales / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D000898:Antibiosis; D001937:Brassica / Q000382:microbiology*; D005658:Fungi / Q000254:growth & development*; D008969:Molecular Sequence Data; D010572:Pest Control, Biological; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D012336:RNA, Ribosomal, 16S