CHARACTERIZATION OF CHILLING-ACCLIMATION-RELATED PROTEINS IN SOYBEAN AND IDENTIFICATION OF ONE AS A MEMBER OF THE HEAT-SHOCK PROTEIN (HSP-70) FAMILY

Through a 5-d exposure at 14-degrees-C/8-degrees-C (day/night), soybean (Glycine max [L.] Merr.) was acclimated to a lower temperature of 8-degrees-C. In order to assess changes in protein synthesis related to chilling acclimation, proteins were labeled in vivo with [S-35]methionine, separated by two-dimensional gel electrophoresis, and the derived autoradiograms were subjected to computer analysis. Two sets of chilling-acclimation-related proteins were characterized following exposure and labeling at 8-degrees-C. One set corresponded to proteins whose synthesis was stimulated in acclimated plants in comparison with non-acclimated plants after transfer to 8-degrees-C for 2 d. The other set also displayed an enhanced synthesis in the acclimated plants versus the non-acclimated plants but after 7 d of exposure at 8-degrees-C. Most of these chilling-acclimation-related proteins were not increased during the acclimation period at 14-degrees-C. Using microsequence analysis, one of these proteins was shown to have a high sequence homology with members of the heat-shock protein (HSP 70) family.