ABA INDUCES 4-AMINOBUTYRATE ACCUMULATION IN WHEAT SEEDLINGS

Accumulation of amino acids and 4-aminobutyrate is induced by ABA treatment in wheat roots. The accumulation of amino acids as well as a decrease in protein level occurs after two hours of hormonal incubation. 4-Aminobutyrate accumulation starts immediately after exposure of wheat roots to ABA. This process shows an optimum of hormone concentration between 50 and 100 muM. Moreover, ABA induces: (i) a transient increase in glutamate decarboxylase activity; (ii) a faster metabolism of [C-14]glutamate; and (iii) a greater synthesis of [C-14]4-aminobutyrate from label glutamate. It is suggested that the ABA-induced accumulation of 4-aminobutyrate is a mechanism involved in the tolerance of plant tissues to stress conditions.