Twelve Rhizoctonia strains were isolated from Chenopodium album, Artemisia vulgaris, Silene cucubalus, and characterised for the number of nuclei, cardinal temperatures, pathogenicity, enzymatic activities, and, preliminarily, for their anastomosis group. Seven among them were binucleate and showed reduced pathogenicity and radial growth (35% less) in comparison with the polynucleate isolates. One polynucleate isolate (R3) showed a phenotype similar to the binucleate ones. Three and 4 electrophoretic patterns relative to the mycelial hydrosoluble proteins were obtained from the binucleate and the polynucleate isolates, respectively; all of them, however, differed from that of the control R. solani strain from French bean. The mycelial hydrosoluble proteins patterns correlated well with enzymatic activities and cardinal temperatures, and only partially with pathogenicities and vegetative compatibilities. Two isolates, one binucleate (R2) and one polynucleate (R3) could be associated to a restricted host range and low virulence and were tested as biocontrol agents against R. solani on radish. In presence of a disease incidence of 89-99% on the control, R2 and R3 reduced symptoms by 12-57% and 38-76% respectively, both in heat-treated and non-treated natural soil. The best activity was observed with antagonist/pathogen inoculum ratio ranging from 40 to 50. R2 and R3 were avirulent on radish. ITS1 ribotyping of the potential biocontrol agents as compared to virulent Rhizoctonia strains is under way, to the purpose of taxonomic comparison and of diagnosis/quantification of both groups in future biocontrol assays.
Isolation, characterisation and use of bi- and polynucleate Rhizoctonia strains as biocontrol agents
FERRARIS, Lucia;VALENTINO, Danila;CARDINALE, Francesca;TAMIETTI, Giacomo
2003-01-01
Abstract
Twelve Rhizoctonia strains were isolated from Chenopodium album, Artemisia vulgaris, Silene cucubalus, and characterised for the number of nuclei, cardinal temperatures, pathogenicity, enzymatic activities, and, preliminarily, for their anastomosis group. Seven among them were binucleate and showed reduced pathogenicity and radial growth (35% less) in comparison with the polynucleate isolates. One polynucleate isolate (R3) showed a phenotype similar to the binucleate ones. Three and 4 electrophoretic patterns relative to the mycelial hydrosoluble proteins were obtained from the binucleate and the polynucleate isolates, respectively; all of them, however, differed from that of the control R. solani strain from French bean. The mycelial hydrosoluble proteins patterns correlated well with enzymatic activities and cardinal temperatures, and only partially with pathogenicities and vegetative compatibilities. Two isolates, one binucleate (R2) and one polynucleate (R3) could be associated to a restricted host range and low virulence and were tested as biocontrol agents against R. solani on radish. In presence of a disease incidence of 89-99% on the control, R2 and R3 reduced symptoms by 12-57% and 38-76% respectively, both in heat-treated and non-treated natural soil. The best activity was observed with antagonist/pathogen inoculum ratio ranging from 40 to 50. R2 and R3 were avirulent on radish. ITS1 ribotyping of the potential biocontrol agents as compared to virulent Rhizoctonia strains is under way, to the purpose of taxonomic comparison and of diagnosis/quantification of both groups in future biocontrol assays.
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