Hormonale Regulation der Phosphatase-Aktivität in nachgereiften und dormanten Embryonen von Agrostemma githago L.

Abstract

Summary The activity of acid phosphatases (EC 3.1.3.2.) in cotyledon tissues of afterripened seeds of Agrostemma githago L. increases dramatically during germination. In seeds blocked by higher temperature (+ 30°C) or in dormant seeds, however, the enzyme activity remains at the initial low level even during several days of imbibition. Treatment of isolated embryos or detached cotyledons with phytohormones markedly influences the development of enzyme activity, the extent and direction of the effects depending on the kind of hormone and the physiological state of the embryo. Gibberellins enhance the development of phosphatase activity in afterripened embryos but are without effect on dormant ones. On the contrary, cytokinins induce the rise of enzyme activity in dormant embryos, but distinctly decrease the phosphatase level in the tissues of afterripened embryos. These specific effects on the activity of acid phosphatases are only partially correlated to the hormonal control of embryo growth. Phytohormones influence the activity of the enzymes in a twofold manner: firstly, by removing the general blockade of development in dormant embryos (unspecific effects of cytokinins and ethylene); secondly, by changing the expression of special genes directly (specific effects of gibberellins and cytokinins).