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 [35S]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 degree 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.