Hormonal Control of Strawberry Axillary Bud Development in Vitro1

Abstract In vitro cultures were used to study the development of axillary bud and stolon tip explants of cultivated strawberry ( Fragaria × ananassa Duch.). Explants cultured on Murashige-Skoog basal media containing kinetin at 1, 5, or 10 mg/liter developed into leafy shoots. Low concentration of kinetin (1 mg/liter) promoted the development of both types of explants into single shoots while higher concentration (10 mg/liter) promoted production of multiple leafy shoots developing from axillary buds of the earlier formed leafy shoots. NAA at 1 mg/liter promoted callus growth from both types of explants. Axillary bud explants developed into stolons when cultured on media containing gibberellic acid (GA 3 ) at 5, 10 or 20 mg/liter. Stolon apices developed into leafy shoots while the second axillary stolon buds of the tips were inhibited when the explants were cultured on GA 3 -containing media. Combinations of GA 3 and kinetin induced the development of axillary bud explants into structures intermediate in form between those of stolons and leafy shoots. Stolon apices and stolon axillary buds at the stolon tips developed into leafy shoots and continuing stolons, respectively, when the explants were cultured on a kinetin-containing medium for one week, and then transferred onto a GA 3 -containing medium. Thus, the developmental pathway of axillary strawberry buds was shown to be responsive to a balance between GA and cytokinins following removal from apical dominance.