Axial Control of Amylase Synthesis and Secretion in Cotyledons of Agrostemma Githago

Abstract

In Agrostemma githago (Caryophyllaceae) starch reserves are located outside the embryo in the perisperm. One of the main degradative enzymes, ce-amylase, is synthesized in and secreted by the cotyledons.The synthesis and secretion of amylase were shown to be under axial control. Benzylaminopurine (BAP)I or gibberellic acid (GA 3 ) replaced axis requirement. BAP probably acted by a general enhancement of metabolism, whereas GA 3 had, like the axis, a specific effect on the cotyledons. The degradation of storage proteins in the cotyledonary tissue was controlled in a similar way.Two arguments raised in the literature against hormonal regulation ofreserve breakdown in dicots are I) that the axis withdraws otherwise inhibitory hydrolysis products from the cotyledons and 2) that reduced activity of hydrolytic enzymes in detached cotyledons is an artefact due to lack of oxygen.These arguments were shown to be most likely invalid.

Cytokinin profile during early phase of germination of gram seeds after application of benzylaminopurine

“…in dicot seeds (De Klerk 1986) and its replacement by applied cytokinins also suggest that germinating seeds synthesize cytokinins. The importance of endogenous cytokinins on reserve mobilization on germinating chick-pea seeds were studied by Munos et al 1990. This study reports comparison of changes in the levels of cytokinins in control and BAP-treated gram seeds during first three days of germination (24, 48 and 72 h after imbibitions).…”