Tall fescue (Lolium arundinaceum) drought tolerance is often enhanced by endophyte infection; however, the physiological mechanisms are not clearly understood. Endophyte-infected (E+) and endophyte-free (E-) clones of two contrasting tall fescue genotypes were drought stressed to investigate differences in endophyte-mediated dehydrin expression. Both genotypes had shown enhanced drought survival due to their endophyte in previous trials. As drought stress intensified, E+ and E- plants of both

more »

... notypes produced dehydrins; however, quantitative and qualitative differences were noted. Genotype 60, a mesic type, accumulated more dehydrins in E+ than in E- plants, whereas genotype 330, a xeric type, displayed low levels of dehydrin and no differences between E+ and E- plants in accumulation patterns. Lack of dehydrin response in genotype 330 suggests that putative dehydrin involvement in endophyte-enhanced tiller survival may not be a universal mechanism in tall fescue. In the absence of endophyte, genotype 330 still expressed much less dehydrin than E- genotype 60, indicating lesser importance of dehydrin in a xeric plant for dehydration tolerance, perhaps benefiting more from constitutive adaptive traits in the host. Keywords: dehydrin, drought, tall fescue