Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2000
Publication Date: N/A
Interpretive Summary: The purpose of this research was to determine whether seed treatment with the fungus Trichoderma virens would induce resistance to the fungal wilt pathogen, Verticillium dahliae, when injected into the stem of cotton plants. Trichoderma virens has been shown to protect cotton plants from attack by pathogens that cause soil-borne seedling diseases. However, its ability to protect cotton against other diseases is unknown. Cotton plants grown from seed treated with two different strains of T. virens had less severe symptoms after stem inoculation with V. dahliae than did untreated controls. The disease reduction occurred in both a susceptible and a moderately resistant cotton cultivar. This suggests that T. virens does induce resistance in parts of the host at a distance from where the fungus is established. These results suggest that seed treatment with T. virens can provide some long-term protection of cotton plants from disease.
Technical Abstract: Trichoderma virens strains that control damping-off of cotton seedlings caused by either Pythium ultimum or Rhizoctonia solani were tested for their ability to induce resistance to Verticillium wilt. Cotton seeds were treated with dried preparations of T. virens and planted in field soil. Plants with six true leaves were inoculated with Verticillium dahliae by stem puncture. After 10 days, plants were rated for Verticillium wilt symptoms and their heights were measured. Two strains of T. virens significantly reduced the diseases severity ratings in V. dahliae-inoculated plants of two cotton cultivars (alpha=0.05). This suggested that T. virens may induce a systemic resistance response in cotton. However, concentrations of terpenoid phytoalexins in stele extracts were not significantly different in plants inoculated with V. dahliae that had been treated with the T. virens than in plants treated with carrier alone. Plants treated with the G4 isolate of T. virens were significantly taller than untreated control plants in the absence of Verticillium. This suggests that some strains of T. virens may have growth promoting activity.