Microbes and Environments
Online ISSN : 1347-4405
Print ISSN : 1342-6311
ISSN-L : 1342-6311
Regular Papers
Biocontrol Potential of an Endophytic Streptomyces sp. Strain MBCN152-1 against Alternaria brassicicola on Cabbage Plug Seedlings
Naglaa HassanSatoko NakasujiMohsen Mohamed ElsharkawyHushna Ara NazninMasaharu KubotaHammad KettaMasafumi Shimizu
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2017 Volume 32 Issue 2 Pages 133-141

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Abstract

In the present study, 77 strains of endophytic actinomycetes isolated from cabbage were screened in order to assess their biocontrol potential against Alternaria brassicicola on cabbage seedlings. In the first and second screening trials, cabbage seedlings pretreated with mycelial suspensions of each isolate were spray-inoculated with A. brassicicola. Strain MBCN152-1, which exhibited the best protection in screening trials and had no adverse effects on seedling growth, was selected for the greenhouse trial. In the greenhouse trial, cabbage seedlings, which had been grown in plug trays filled with soil mix containing spores of MBCN152-1 (1×108 spores g−1 of soil mix), were spray-inoculated with A. brassicicola and grown in greenhouse conditions. MBCN152-1 reduced disease incidence and significantly increased the number of viable seedlings. The efficacy of MBCN152-1 against damping-off caused by seed-borne A. brassicicola was then evaluated. Cabbage seeds, artificially infested with A. brassicicola, were sown in soil mix containing MBCN152-1 spores. The disease was completely suppressed when infested seeds were sown in a soil mix blended with MBCN152-1 at 1.5×107 spores g−1 of soil mix. These results strongly suggest that MBCN152-1 has the potential to control A. brassicicola on cabbage plug seedlings. MBCN152-1 was identified as a Streptomyces humidus-related species based on 16S rDNA sequencing. Scanning electron microscopy showed that the hyphae of MBCN152-1 multiplied on the surface of the seedlings and penetrated their epidermal cells. In conclusion, strain MBCN152-1 is a promising biocontrol agent against A. brassicicola on cabbage plug seedlings.

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© 2017 by Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions.
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