Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2006
Publication Date: 8/15/2007
Citation: Sanchez, V., Rebellodo, O., Piscaso, R.M., Cardenas, E., Cordova, J., Gonzalez, O., Samuels, G.J. 2007. In Vitro Antagonism of Tielaviopsis Paradoxa by Trichoderma Longibrachiatum. Mycopathologia. 163:49-58.
Interpretive Summary: Fungi in the genus Trichoderma are effective in the biological control of plant diseases. The mechanisms by which these biological control agents work are not known. In this research Trichoderma was shown to inhibit the growth of a common plant pathogen that causes black rot of agave. When growing with the plant pathogen, isolates of Trichoderma produced chemical substances that caused the plant pathogen to break down and die. It was determined that the Trichoderma produces chemicals that can destroy the cell walls of the plant pathogen. This research will be used by plant pathologists who are working to develop ways of controlling plant diseases without chemicals.
Technical Abstract: Seventy-nine Trichoderma strains were isolated from soil taken from 28 commercial plantations of Agave tequilana cv. azul in the State of Jalisco, México. Nine of these isolates produced nonvolatile metabolites that completely inhibited the growth of the agave parasite Thielaviopsis paradoxa on potato dextrose agar plates. These isolates were identified as Trichoderma longibrachiatum on the basis of their morphology and sequence analysis of ITS-1, 5.8S, and ITS-2 fragments from rDNA genes. Mycoparasitism of Th. paradoxa by T. longibrachiatum strains in dual cultures was examined by scanning electron microscopy. The Trichoderma hyphae grew alongside the Th. paradoxa hyphae but there was no apparent penetration of the Thielaviopsis by the Trichoderma. Aleurioconidia of Th. paradoxa were penetrated by the Trichoderma. Both hyphae and aleurioconidia of Th. paradoxa lost turgor pressure, wrinkled, collapsed and finally disintegrated. All nine Trichoderma isolates produced proteases, '-1,3-glucanases and chitinase in liquid culture, which would be responsible for degradation of hyphae of the Thielaviopsis. These results demonstrate that the mycoparasitism and nonvolatile metabolites are involved in the biological control of Th. paradoxa by T. longibrachiatum.