Isolation and characterization of endophytic actinomycetes from Chinese cabbage roots as antagonists to Plasmodiophora brassicae.
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.
Lee
Sun Og
SO
Bio-Control Research Team, Chemical Biotechnology Research Center, Korea Research Institute of Chemical Technology, Daejeon 305-600, Korea.
Choi
Gyung Ja
GJ
Choi
Yong Ho
YH
Jang
Kyoung Soo
KS
Park
Dong Jin
DJ
Kim
Chang Jin
CJ
Kim
Jin-Cheol
JC
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
D012336:RNA, Ribosomal, 16S