The Development of Leaf Heat-Tolerance during the Local Heating of Seedling Organs

Experiments using cucumber (Cucumis sativusL.), wheat (Triticum aestivumL.), and barley (Hordeum vulgareL.) seedlings showed that actinomycin D partially inhibited an increase in the heat-tolerance of leaves heated at 38°C for 7 h but did not affect this index when the roots were heated. Exogenous ABA increased heat-tolerance in both cases. These results, with regard to the data demonstrating an important contribution of protein synthesis to the specific increase in heat-tolerance during the heat acclimation of intact plants, make it possible to conclude that the development of leaf heat-tolerance resulting from the local heating of shoots depends on the induced synthesis of mRNAs and respective proteins. At the same time, there is little or no such dependence during root heating. ABA manifested itself as a factor of a general, nonspecific increase in heat-tolerance during the local heating of both shoots and roots.