HEAT-SHOCK RESPONSE IN HEAT-TOLERANT AND NONTOLERANT VARIANTS OF AGROSTIS-PALUSTRIS HUDS

The heat-shock response in heat-tolerant variants (SE) and nontolerant variants (NSB) of creeping bentgrass (Agrostis palustris Huds.) was i nvestigated. Both variants were derived from callus initiated from a s ingle seed of the cultivar Penncross. SE and NSB synthesized heat-shoc k proteins (HSPs) of 97, 83, 70, 40, 25, and 18 kD. There were no majo r differences between SE and NSB in the time or temperature required t o induce the heat-shock response. When the HSPs synthesized by SE and NSB were analyzed by two-dimensional gel electrophoresis, it was appar ent that SE synthesized two to three additional members of the HSP27 f amily, which were smaller (25 kD) and more basic than those synthesize d by NSB. Analysis of F-1 progeny of NSB x SB indicated that 7 of the 20 progeny-did not synthesize the additional HSP25 polypeptides. These progeny were significantly less heat tolerant than progeny that did s ynthesize the additional HSP25 polypeptides. The chi(2) test of indepe ndence (chi(2) = 22.45, P < 0.001) indicated that heat tolerance and t he presence of the additional HSP25 polypeptides are linked traits.