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

A quantitative cytochemical analysis of glucose-6-phosphatedehydrogenase activity of deeply dormant seeds of Avena fatuashowed that although the enzyme activity is present in mostcell types of the embryo and seed, it is only in the embryothat activity is increased on treatment with GA₃ to break dormancy.This would appear to happen prior to any measurable embryonicaxis growth, and supports the idea that activation of the pentosephosphate pathway is an early event in dormancy break. A similar,though less marked, change occurred in less dormant seeds ofA. fatua, but could not be detected in dormant seeds of Lactucasaliva. Dry seeds of L. sativa and weakly dormant A. fatua containedtwice the activity seen in seeds imbibed with either water orGA₃, indicating that this might be a marker of low levels ofdormancy. Avena fatua, Lactuca sativa, seeds, dormancy, pentose phosphate pathway, cytochemistry, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase