Submitted to: Phytopathology
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2004
Publication Date: 6/1/2004
Citation: Cohen, M.F., Yamasaki, H., Mazzola, M. 2004. Suppression of rhizoctonia root rot and increased recovery of nos+ streptomyces spp in rapeseed meal amended soils. Phytopathology. 94:S20. Interpretive Summary: Abstract only.
Technical Abstract: Rapeseed seed meal (RSM) amendment to orchard soils suppressed apple root infection by R. solani AG-5, and resulted in significantly higher populations of Streptomyces spp. in soil and recovered from apple roots. Although a preponderance of Streptomyces spp. resident to treated soils inhibited in vitro growth of R. solani, the vast majority resident to the rhizosphere were not antagonistic toward the pathogen and RSM amendment did not deter sapropphytic growth of R. solani. Preliminary results from split-root studies indicate that seedlings planted in RSM-amended soil display heightened systemic resistance against R. Solani. A large proportion of Streptomyces spp. recovered from the apple rhizosphere produced nitric oxide (NO) via NO synthase and production of nitrogen oxides by baceterial nitrification was greater than 100-fold higher in RSM-amended soils than control or glucose-amended soils. Based on colonization we have observed in the field, we hypothesize functions for NO in RSM-mediated disease suppression.