Two isolates of Rhizoctonia, R2 binucleate and R3 polynucleate, effective against R. solani on radish were investigated for their mode of action. Tomato seedlings were grown in soil colonised with R2, R3, a non-pathogenic suppressive Fusarium oxysporum strain, as standard, or in steamed soil. Plant leaves were challenge inoculated with Botrytis cinerea. Laminarinase and chitinase activity was determined in leaves before and after inoculation with B. cinerea. Microscopic observations of root/fungus interaction were also made. Root colonisation by the antagonists caused a significant increase of the tested enzymes in the leaves, which was higher in those inoculated with B. cinerea, showing induced systemic resistance. A reduction of B. cinerea lesions was sometime observed. R3 promoted tomato growth. For molecular classification, a taxonomically relevant ITS trait was amplified from R2 and R3. Amplicons were subjected to RFLP analysis in parallel with the pathogenic R. solani FAG and a whole collection of tester strains covering all known R. solani anastomosis groups. ITS from R2, R3 and FAG were entirely sequenced. BLAST analysis revealed 100% identity of R3 with R. solani AG4; FAG also showed the highest similarity, although less than R3, to AG4 isolates worldwide. R2 confirmed to be most similar to other binucleate Rhizoctonia spp.. Diagnostic primers were designed based on ITS sequence alignment between R2, R3 and FAG. They are being tested for their efficiency and specificity as a tool for further analyses on R2 and R3 antagonistic mechanism on plant roots challenged by FAG.
Characterisation of bi- and polynucleate antagonistic Rhizoctonia strains
FERRARIS, Lucia;VALENTINO, Danila;CARDINALE, Francesca;TAMIETTI, Giacomo
2004-01-01
Abstract
Two isolates of Rhizoctonia, R2 binucleate and R3 polynucleate, effective against R. solani on radish were investigated for their mode of action. Tomato seedlings were grown in soil colonised with R2, R3, a non-pathogenic suppressive Fusarium oxysporum strain, as standard, or in steamed soil. Plant leaves were challenge inoculated with Botrytis cinerea. Laminarinase and chitinase activity was determined in leaves before and after inoculation with B. cinerea. Microscopic observations of root/fungus interaction were also made. Root colonisation by the antagonists caused a significant increase of the tested enzymes in the leaves, which was higher in those inoculated with B. cinerea, showing induced systemic resistance. A reduction of B. cinerea lesions was sometime observed. R3 promoted tomato growth. For molecular classification, a taxonomically relevant ITS trait was amplified from R2 and R3. Amplicons were subjected to RFLP analysis in parallel with the pathogenic R. solani FAG and a whole collection of tester strains covering all known R. solani anastomosis groups. ITS from R2, R3 and FAG were entirely sequenced. BLAST analysis revealed 100% identity of R3 with R. solani AG4; FAG also showed the highest similarity, although less than R3, to AG4 isolates worldwide. R2 confirmed to be most similar to other binucleate Rhizoctonia spp.. Diagnostic primers were designed based on ITS sequence alignment between R2, R3 and FAG. They are being tested for their efficiency and specificity as a tool for further analyses on R2 and R3 antagonistic mechanism on plant roots challenged by FAG.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
