Wild-Type Levels of Abscisic Acid Are Not Required for Heat Shock Protein Accumulation in Tomato

Levels of endogenous abscisic acid (ABA) in wild type were not required for the synthesis of heat shock proteins in detached leaves of tomato (Lycopersicon esculentum Mill., cv Ailsa Craig). Heat-induced alterations in gene expression were the same in the ABA-deficient mutant of tomato, flacca, and the wild type. Heat tolerance of the mutant was marginally less that the wild type, and in contrast, ABA applications significantly reduced the heat tolerance of wild-type leaves. It was concluded that elevated levels of endogenous ABA are not involved in the tomato heat shock response.