Hormone levels and protein patterns in dormant and non-dormant buds of strawberry, and induction of bud break by gibberellic acid

Abstract

Strawberry runners are characterized by the occurrence of a dormant bud followed by a consequent non-dormant bud. Dormant buds were found to contain relatively low levels of endogenous gibberellic acid (GA 3 ) and enhanced levels of abscisic acid (ABA), as compared with non-dormant buds. The lower contents of GA3 in the dormant buds were also accompanied by attenuated levels of auxin (IAA) and cytokinins (zeatin and benzyladenine). Exogenous application of GA 3 (50 ppm) to the latent buds could achieve 97% break of their onset of dormancy. Histological examination showed that the initial stage of bud formation was similar in the dormant and non-dormant buds. Thus, triggering the burst of a dormant bud by GA 3 treatment is assumed to occur in the second developmental stage. Comparison of the proteinbanding patterns in the dormant and non-dormant buds showed a slight difference in the number of protein bands, but a wide variation in their types. The results suggest differences in the regulation of gene expression, perhaps controlled mainly by ABA in the dormant buds and GA 3 in the active state. KEY WORDS: Abscisic acid, auxin, cytokinin, zeatin, benzyladenine, histology, PAGE-electrophoresis Egyptian Journal of Botany Vol.5 2003: 35-42