Abstract
An endophytic actinomycete, isolate R-5 of Streptomyces galbus Frommer, that has promising potential as a biocontrol agent was originally isolated from field-grown rhododendron. In this study, the mode of entry of R-5 into leaves of tissue-cultured seedlings of rhododendron was investigated in connection with its production of cell wall-degrading enzymes. Light and scanning electron microscopy (SEM) revealed that R-5 grew on leaf surfaces and entered leaf tissues via stomata and that the internal mycelia grew out of stomata after colonization in host tissues. Micromanipulation at the SEM level demonstrated a prominent depression in the host surface at the interfaces with the mycelia, suggesting that such a depression could be caused by degradation of cell wall components by hydrolytic enzymes secreted from R-5 mycelia. In subsequent plate assays, R-5 produced cellulase, pectinase, xylanase, and nonspecific esterase when cultured in liquid medium. Moreover, R-5 multiplied in mineral medium containing cellulose, pectin, or xylan as a single carbon source. Thus, R-5 mycelia could degrade host cell walls at contact sites and probably utilize the degradation products as carbon sources.
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Received: May 16, 2002 / Accepted: July 9, 2002
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Minamiyama, H., Shimizu, M., Kunoh, H. et al. Multiplication of isolate R-5 of Streptomyces galbus on rhododendron leaves and its production of cell wall-degrading enzymes. J Gen Plant Pathol 69, 65–70 (2003). https://doi.org/10.1007/s10327-002-0014-y
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DOI: https://doi.org/10.1007/s10327-002-0014-y