Submitted to: Pacifichem Symposium
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2000
Publication Date: N/A
Technical Abstract: A study of the biocontrol of Rhizoctonia solani-incited cotton seedling disease by Trichoderma virens indicates that the primary biocontrol mechanism is induction of disease resistance in the cotton root by T. virens. Colonization and penetration of the developing root system by the biocontrol agent stimulated the synthesis of increased levels of the terpenoid pathway intermediates desoxyhemigossypol (dHG) and hemigossypol (HG), and the end product, gossypol (G). dHG and HG were strongly inhibitory to the pathogen, R. solani, while G was toxic only at much higher concentrations. Trichoderma spp. were much more resistant to terpenoids than the pathogen. A comparison of biocontrol efficacy and induction of terpenoid synthesis in cotton roots by strains of Trichoderma, indicated that there was a strong correlation (+0.89) between these two phenomena. Assay and fractionation of T. virens culture filtrate indicated that the fungus synthesizes a protein that stimulates terpenoid production in cotton roots prior to pathogen attack, and thereby induces resistance to seedling disease.