Journal of General Plant Pathology

, Volume 75, Issue 1, pp 27–36

A promising strain of endophytic Streptomyces sp. for biological control of cucumber anthracnose

  • Masafumi Shimizu
  • Sachiko Yazawa
  • Yusuke Ushijima
Fungal Diseases

DOI: 10.1007/s10327-008-0138-9

Cite this article as:
Shimizu, M., Yazawa, S. & Ushijima, Y. J Gen Plant Pathol (2009) 75: 27. doi:10.1007/s10327-008-0138-9

Abstract

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.

Keywords

Colletotrichum orbiculareEndophytic StreptomycesCucumis sativus L.Biocontrol

Copyright information

© The Phytopathological Society of Japan and Springer 2008

Authors and Affiliations

  • Masafumi Shimizu
    • 1
  • Sachiko Yazawa
    • 1
  • Yusuke Ushijima
    • 1
  1. 1.Laboratory of Crop Production and Ecology, Graduate School of BioresourcesMie UniversityTsuJapan