Axial control om amylase synthesis and secretion in cotyledons of Agrostemma githago

In Agrostemma githago (Caryophyllaceae) starch reserves are located outside the embryo in the perisperm. One of the main degradative enzymes, a-amylase, is synthesized in and secreted by the cotyledons. The synthesis and secretion of amylase were shown to be under axial control. Benzylaminopurine (BAP)1 or gibberellic acid (GAj) replaced axis requirement. BAP probably acted by a general enhancement of metabolism, whereas GA3 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 of reserve breakdown in dicots are 1) 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.