A promising strain of endophytic Streptomyces sp. for biological control of cucumber anthracnose
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In a survey for effective biocontrol agents of Colletotrichum orbiculare, causal agent of cucumber anthracnose, 43 (MBCu series) and 135 (MBPu series) endophytic actinomycete strains were recovered from surface-sterilized organs of cucumber (Cucumis sativus) and pumpkin (Cucurbita moschata) plants, respectively. The strains were cultured with C. orbiculare on IMA-2 agar medium to determine their in vitro antagonistic ability. Eleven strains that strongly inhibited hyphal growth of the pathogen were selected as potent antagonists. Detached cotyledons of cucumber were soaked in a spore suspension of an antagonistic strain 1 day before challenge-inoculation with the pathogen, and six of these antagonists (MBCu-32, 36, 42, 45, and 56, and MBPu-75) significantly reduced the number and size of the lesions on the cotyledons compared to the untreated control. In the same way, these six strains inhibited lesion development on attached leaves of 3-week-old cucumber seedlings. Strain MBCu-56, the most suppressive of the strains, was selected for further tests. Its suppressiveness increased as concentrations increased; pretreatment of leaves with the strain at 107, 108 and 109 cfu/ml suppressed disease by 72, 79 and 93%, respectively. These results strongly indicated that MBCu-56 has strong potential for controlling cucumber anthracnose. Based on the taxonomic characteristics and 16S rDNA sequence, MBCu-56 was identified as Streptomyces sp. With scanning electron microscopy, the substrate mycelia of the strain were seen to colonize the surface of leaves above the cuticle. Some hyphae also penetrated and grew underneath the cuticle.
KeywordsColletotrichum orbiculare Endophytic Streptomyces Cucumis sativus L. Biocontrol
We are grateful to Dr. S. Karita, Miss H. Kado and Miss M. Kasai of Mie University for technical assistance in the 16S rDNA sequencing. This study is contribution no. 40 from Laboratory of Crop Production and Ecology, Graduate School of Bioresources, Mie University. The work was partially supported by a Grant-in-Aid for Young Scientists (B) (17780034) from the Ministry of Education, Culture, Sports, Science and Technology of Japan to Masafumi Shimizu.
- Castillo U, Harper JK, Strobel GA, Sears J, Alesi K, Ford E, Lin J, Hunter M, Maranta M, Ge H, Yaver D, Jensen JB, Porter H, Robison R, Millar D, Hess WM, Condron M, Teplow D (2003) Kakadumycins, novel antibiotics from Streptomyces sp. NRRL 30566, an endophyte of Grevillea pteridifolia. FEMS Microbiol Lett 224:183–190PubMedCrossRefGoogle Scholar
- Miyadoh S, Hamada M, Hotta K, Kudo T, Seino A, Suzuki K, Yokota A (eds) (2001) Identification manual of actinomycetes. Business Center for Academic Societies Japan, Tokyo (in Japanese)Google Scholar
- Okazaki T, Takahashi K, Kizuka M, Enokita R (1995) Studies on actinomycetes isolated from plant leaves. Annu Rep Sankyo Res Lab 47:97–106Google Scholar
- Rothrock CS, Gottlieb D (1981) Importance of antibiotic production in antagonism of selected Streptomyces species to two soil-borne plant pathogens. J Antibiotics 34:830–835Google Scholar
- Rothrock CS, Gottlieb D (1984) Role of antibiosis in antagonism of Streptomyces hygroscopicus var. geldanus to Rhizoctonia solani in soil. Can J Microbiol 30:1440–1447Google Scholar
- Shimizu M, Suzuki T, Mogami O, Kunoh H (2005) Disease resistance of plants induced by endophytic actinomycetes. In: Tsuyumu S, Leach EJ, Shiraishi T, Wolpert T (eds) Genomic and genetic analysis of plant parasitism and defense. APS, St Paul, pp 292–293Google Scholar
- Shirling EB, Gottlieb D (1966) Methods for characterization of Streptomyces species. Int J Syst Bacteriol 16:313–340Google Scholar
- Tahvonen R (1982) Preliminary experiments into the use of Streptomyces spp. isolated from peat in the biological control of soil- and seed-borne diseases in peat culture. J Sci Agric Soc Finl 54:357–369Google Scholar
- Tapio E, Pohto-Lahdenperä A (1991) Scanning electron microscopy of hyphal interaction between Streptomyces griseoviridis and some plant pathogenic fungi. J Agric Sci Finl 63:435–441Google Scholar
- van Driesche RG, Bellows TS Jr (eds) (1996) Biological control. Chapman & Hall, New YorkGoogle Scholar