Regulation of α-amylase isoenzyme expression in Araucaria araucana by gibberellic and abscisic acids

Abstract

Expression of α-amylase (EC 3.2.1.1) isoenzymes present in the embryos and mega-gametophytes of Araucaria araucana seedlings was studied under gibberellic acid (GA 3) and abscisic acid (ABA) treatments and after 90 hr of imbibition in 20 mM of β-chloroethyltrimethylammonium (CCC), a GA 3 biosynthesis inhibitor. When CCC was used, α-amylase activity in the treated embryos decreased to 28% with respect to the controls. The isoenzymes of R m 0.42 and 0.51 were greatly affected. When the embryos were imbibed simultaneously in the presence of 20 mM CCC and 10 −5 M of GA 3, α-amylase activity and the expression of isoenzymes were restored with respect to controls. ABA at 10 −4 and 10 −5 M decreased α-amylase activity of embryos to 67 and 81%, respectively. Expression of isoenzymes of R m 0.51 was greatly decreased by ABA but the effect on the others was small. Isoenzyme expression of mega-gametophytic α-amylase was not affected by CCC, GA 3 or ABA treatment.