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Mycoparasitism of Pythium ultimum by Antagonistic Binucleate Rhizoctonia Isolates in Agar Media and on Capsicum Seeds
Author(s) -
Siwek K.,
Harris A. R.,
Scott E. S.
Publication year - 1997
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1997.tb00343.x
Subject(s) - hypha , biology , pythium ultimum , rhizoctonia , pathogen , botany , microbiology and biotechnology , pythium , rhizoctonia solani , agar , agar plate , damping off , phycomycetes , seedling , horticulture , bacteria , inoculation , genetics
Hyphal interactions between two antagonistic binucleate Rhizoctonia isolates (BNR) and the seedling dampingoff pathogen, Pythium ultimum var. sporangiiferum, were observed by both light‐and scanning electron microscopy (SEM), on agar media and on capsicum seeds in sterilized potting mix. Both BNR isolates displayed similar mycoparasitic behaviour towards P. u. sporangiiferum on agar media. This included parallel growth along the pathogen hyphae, formation of hook‐shaped hyphal tips and coils on the surface of P. u. sporangiiferum hyphae and penetration and growth within pathogen structures. Disruption of cytoplasmic streaming and disorganisation of pathogen cytoplasm were also observed. SEM observations revealed alterations in P. u. sporangiiferum cell wall structure and the presence of penetration holes apparently due to digestion by the BNR. P. u. sporangiiferum was also parasitised by both BNR isolates on capsicum seed coats, with parallel growth, hook formation and coils commonly observed. The above observations indicated that mycoparasitism is a possible mode of action of BNR against P. u. sporangiiferum.