Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: September 16, 1999
Publication Date: N/A
Technical Abstract: Several Trichoderma virens (Gliocladium virens) strains have good biocontrol activity against Rhizoctonia damping-off of cotton. In previous studies, biocontrol activity against Rhizoctonia solani on cotton was retained in some UV mutants that were deficient for antibiotic production or mycoparasitism suggesting that some other factor is important in biocontrol strains of T. virens that have higher levels of terpenoid phytoalexins in the roots than do seedlings treated with ineffective strains. This suggests that the biocontrol strains can induce resistance responses in the host. Sterile culture filtrates from the effective biocontrol strains also can stimulate increased phytoalexin levels. The activity in the culture filtrates was present in several different media, was heat stable, was insoluble in chloroform, passed through a 5K molecular weight cut off filter, and was sensitive to treatment by proteinase K. This suggests that the elicitor activity is due to a protein or proteins. Efforts are being made to isolate the elicitor or elicitors.