ACCUMULATION OF HEAT-STABLE PROTEINS IN WINTER-WHEAT SEEDLINGS DURINGHYPOTHERMIA

The synthesis and accumulation of stress-induced heat-stable proteins were studied in etiolated shoots of winter wheat (Triticum aestivum L. ) seedlings during their cold acclimation at 4 degrees C for nine days . To this end, we used the methods of radioactive amino acid incorpora tion into protein, one-dimensional electrophoresis in PAAG, and fluoro graphy. Cold acclimation induced the synthesis of a number of polypept ides with mol wts of 209, 196, 169, 66, 50, and 41 kD. Accumulation of these proteins was correlated with increased freezing tolerance of th e seedlings. These proteins are assumed to be dehydrins. Heat-stable p roteins of hardened wheat seedlings were compared with those of other hardened cereals (Secale cereale L., Avena sativa L., and Zea mays L.) . Winter rye and wheat synthesized several common heat-stable polypept ides (209, 50, and 41 kD). Unlike rye and wheat, hardened oat and maiz e seedlings synthesized heat-stable proteins with low and medium mol w ts, apparently because of the poor freezing resistance of these specie s.