1a.Objectives (from AD-416):
The objective of this research is to test in the laboratory and growth chambers, the efficacy of selected Trichoderma isolates in colonizing seedlings of annual plant species and evaluating the isolates’ abilities to induce plant defense responses and reduce plant disease. ARS is studying the same effects in the perennial tree species Theobroma cacao (cacao) and comparisons between the interactions observed in different plant species is of special interest. The Trichoderma isolates to be studied were collected in tropical environment where cacao is grown and little information exist concerning how the Trichoderma isolates perform in annual plant species. The data gathered will answer questions as to the uniqueness of the Trichoderma/cacao interaction and potentially broaden the number of cropping systems any Trichoderma based products developed might be applicable too. The latter aspect may be critical to successfully marketing Trichoderma based products for management of diseases in cacao in addition to other crops.
1b.Approach (from AD-416):
ARS is carrying out transcriptome analysis for Trichoderma species endophytic on cacao. The Trichoderma/cacao interaction is considered unique in that the Trichoderma colonizes the above ground plant parts and not just roots. In order to identify Trichoderma transcript expression patterns specific to the Trichoderma/cacao interaction we need to know the expression pattern of Trichoderma in other crops. The Cooperator will inoculate pepper, cotton, corn, and wheat with Trichoderma isolates endophytic on cacao. Trichoderma colonization of roots and stems will be measured. RNA will be isolated from roots and stems of annual species and Trichoderma gene expression studied in these tissues. The data gathered will be compared to data gathered by ARS on the Trichoderma/cacao interaction. Growth chamber assays will be carried out evaluating the ability of Trichoderma isolates to reduce disease in pepper (Capsicum annuum) caused by Phytophthora capsici. Depending on results from the transcript analysis, additional disease assays will be carried out on other plant/pathogen systems.
The collaborator at New Mexico State University is acquiring permits for acquiring non-native isolates of the beneficial fungus Trichoderma from the ARS laboratory. The Trichodema isolates were collected from cacao fields in South and Central America. The Trichoderma isolates will be studied for their usefulness in reducing losses due to the plant pathogen Phytophthora capsici in pepper at the New Mexico State University laboratory and are also being studied for their usefulness in managing cacao diseases at the ARS laboratory.