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Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/5/2003 Publication Date: 2/2/2004 Citation: Hanson, L.E., Howell, C.R. 2004. Elicitors of plant defense responses from biological control strains of trichoderma virens. Phytopathology. Interpretive Summary: Interpretive summary Effective biocontrol strains of the fungus Trichoderma virens can cause cotton plants to produce defense-related compounds. The activity is found in culture filtrates from the fungal strains. Results from our research indicate that the material that induces production of plant defense compounds consists of proteins. When proteins in the culture filtrate were separated, four induced defense-compounds in cotton seedlings. One showed antigenic similarity to an ethylene-inducing xylanase reported from T. viride. A band of molecular mass of about 18 kDa was consistently active. The first 19 amino acids for this protein were determined. Technical Abstract: Abstract. Effective biocontrol strains of Trichoderma virens can induce the production of defense-related compounds in the roots of cotton. Ineffective strains do not induce these compounds to significant levels. This elicitation-activity is produced in culture filtrates, is heat stable, insoluble in chloroform, passes through a 5K MWCO filter, but not a 3K MWCO filter, and is sensitive to treatment by proteinase K. When the active material was subjected to SDS-PAGE, several bands were present in the material from biocontrol-active strains that were lacking in inactive strains. When eluted and tested for elicitation activity, four band stimulated cotton terpenoid production with renaturation. One band showed cross-reaction with an antibody to the ethylene-inducing xylanase from T. viride. Another band of approximately 18kDa, gave significant stimulation of cotton terpenoid production and increased peroxidase activity in cotton radicles in all tests, with or without renaturation. The 18kDa protein was subjected to amino-terminal sequence analysis, and the first 19 amino acids at the amino terminus were determined to be DTVSYDTGYDNGSRSLNDV. A database homology search using the BLASTn algorithm showed the highest similarity to a serine proteinase from Fusarium sporotrichioides. |
