Control of the Formation of Amylases and Proteases in the Cotyledons of Germinating Peas

Abstract

Protease activity increased in attached cotyledons of germinated peas (Pisum sativum L. cv. Alaska) as the stored proteins declined but did not increase in excised cotyledons incubated for the same length of time. Cotyledons of seeds germinated in the presence of a casein hydrolysate solution developed less protease activity than did those germinated on water. These results suggest that accumulation of amino acids regulates the protease level in the cotyledons of germinating peas.In contrast to protease, alpha- and beta-amylase increased during incubation of excised pea cotyledons. Their increase was inhibited by abscisic acid. Abscisic acid did not inhibit (14)C-leucine incorporation into protein or reduce the respiratory rate in the cotyledons; hence, its effect on amylase formation was not the result of a general inhibition of metabolism. An ether-soluble acid fraction, which would contain any abscisic acid present in the material, inhibited amylase formation more when it was obtained from imbibed seeds than when it was obtained from cotyledons of seeds germinated for 10 days. These and other results suggest that amylase formation in germinating peas is regulated by abscisic acid.