GENETIC EXPRESSION PROFILES OF THE TALL FESCUE-ENDOPHYTE SYMBIOSIS RELATING TO DROUGHT STRESS TOLERANCE
Forage-Animal Production Research
2010 Annual Report
1a.Objectives (from AD-416)
To characterize genetic expression profiles of drought stressed tall fescue containing novel endophytes strains and verify gene expression profiles of selected genes.
1b.Approach (from AD-416)
Tall fescue, KY31, containing six novel endophyte strains, plus the endophyte-free and KY31 with wild-type endophyte will be evaluated under different drought stress regimes to characterize differences in gene expression profiles and correlate these with phenotypic response to the treatments. The KY31 lines differ in their response to drought stress and the goal is to compare gene expression levels and identify putative genes that are over- or under-expressed in response to the stress experiments that correlate with increased drought tolerance. ARS is developing an expression profiling tool for tall fescue for analysis of whole genome expression comparisons. This will be used to compare expression of the different KY31 lines containing the different endophyte strains to determine the effect of gene expression, using real time PCR techniques, in drought tolerance response. Three replications comparing non-stressed (beginning of the experiment) and three replications of stressed material for each of the lines will be evaluated. RNA will be isolated from pseudostems of each line for each treatment for analysis.
ARS and University of Arkansas have generated endophyte infected (E+) and endophyte free (E-) clone pairs. The clone pairs are being propagated to provide sufficient material for drought studies. These then will be tested under drought stress treatments for phenotypic analysis of E+/E- comparisons and Ribo Nucleic Acid (RNA) isolation for gene expression analysis. The first drought experiments will be done on individual clones of KY16 and KY19. In addition, a number of these clone pairs have been transferred to the field in a replicated trial for evaluation under field conditions. Performance of this agreement is monitored by USDA-ARS, Forage-Animal Production Research Unit scientists being intimately involved as collaborators in the agreement project, and calling, emailing, or meeting with the collaborator on an as needed basis to alter experimental design.