Abstract:Changes of proteins in the rice ( Oryza sativa L. ) seedlings from different stress pretreatments were compared for exploring the mechanism of cross adaptation to different stresses. The chilling resistances of rice seedlings (under 1 ℃, 150 μmol•m-2•s-1 PFD for 2 days) were enhanced distinctly by salt, heat shock and cold pretreatments. The survial rates of the pretreated rice seedlings after being recovered from chilling injury for 2 days were greatly higher than those of nonpretreated seedlings. The contents of total soluble protein and heat-unstable protein from the different kinds of pretreated seedlings showed a similar trend of changes. In comparing with the nonpretreated seedlings, total soluble protein and heat-unstable protein were lower just after pretreatment and chilling injury but became higher after recovery for 2 days. The heat-stable protein in the seedlings pretreated by cold or heat shock was higher than those of the nonpretreated seedlings at all three sampling time ( after pretreated; after chilling injury; after recovery for 2 days). However, the change of heat-stable protein in salt pretreated seedlings was similar to the changes of the soluble and heat-unstable proteins. SDS-polyacrylamide gel electrophoresis analysis indicated that the component changes of the soluble, heat-stable and heat-unstable proteins among the three pretreated seedlings had both common newly induced polypeptides and different specific newly polypeptides by comparison with the nonpretreated seedlings. These results suggested that the cross adaptation of plants to different environmental stresses involved certain common molecular mechanism, yet the plants might not adapt the same environmental stress with the same resistance mechanism.