Localization of Glucose-6-phosphate Dehydrogenase Activity in Seeds and its Possible Involvement in Dormancy Breakage

Abstract

A quantitative cytochemical analysis of glucose-6-phosphate dehydrogenase activity of deeply dormant seeds of Avena fatua showed that although the enzyme activity is present in most cell types of the embryo and seed, it is only in the embryo that activity is increased on treatment with GA3 to break dormancy. This would appear to happen prior to any measurable embryonic axis growth, and supports the idea that activation of the pentose phosphate pathway is an early event in dormancy break. A similar, though less marked, change occurred in less dormant seeds of A. fatua, but could not be detected in dormant seeds of Lactuca saliva. Dry seeds of L. sativa and weakly dormant A. fatua contained twice the activity seen in seeds imbibed with either water or GA3, indicating that this might be a marker of low levels of dormancy.