Induction of cold hardiness by salt stress involves synthesis of cold-and abscisic acid-responsive proteins in potato (Solanum commersonii Dun.).

Salt stress has been found to increase frost tolerance in some herbaceous species. In an attempt to understand the molecular basis of the frost tolerance induced by salt stress, the effect of salt (100 mM NaCl) on total proteins in stem-cultured potato plantlets (Solanum commersonii Dun) was analyzed on two-dimensional gels. Nine salt-induced proteins were identified after 24 h salt treatment, at which time cold hardiness increased by three degrees. Direct comparisons of the proteins with those induced by cold- and abscisic acid(ABA)-treatments revealed that five of the salt-induced proteins were also induced by cold(4 degrees/2 degrees C)-treatment and seven were also induced by ABA(40 mu M)-treatment. Three proteins (M(r)/pIs 13/7.0, 27/6.6 and 48/6.9) were inducible in both cold- and ABA-treatments in association with frost hardening. After 6 h salt treatment, endogenous ABA levels in plantlet leaves showed a transient six-fold increase before cold hardiness developed. The results suggest that salt-induction of cold hardiness involves the synthesis of cold-and ABA-responsive proteins and the alteration of protein synthesis is mediated by ABA elevated upon salt stress. This study also suggests that a subset of proteins induced by cold- and ABA-treatments are related to salt stress.