Abstract
Exposure of young spinach seedlings (Spinacia oleracea L. cv Bloomsdale) to 5 degrees C leads to an increase in the synthesis of several 79-kilodalton proteins that are present in leaf tissue grown at 20 degrees C. Protein sequence analyses and immunological cross-reactivity indicate that this group of proteins belongs to the 70-kilodalton heat-shock family. Steady-state transcript levels and protein synthesis are increased two- to threefold within 1 day, but immunoblot analyses suggest that the steady-state concentration of this protein group in leaf tissue only gradually accumulates at low temperature. It is proposed that the increased synthesis of several members of the 70-kilodalton heat-shock family could result from an influence of low temperature on protein folding and/or assembly processes.