Studies on the Fragmented Shoot Apex of Grapevine: II. FACTORS AFFECTING GROWTH AND DIFFERENTIATION IN VITRO

The hormonal and nutritional requirements for the culture offragmented shoot apices of grapevine were examined. Benzyladenineat 10 µM added to the full strength Murashige and Skoogbasal medium was found to be optimal for both the initial growthof apical fragments to individual leaves, and the subsequentcapacity of these leaves to produce adventitious shoots. Serialsectioning of the site of shoot proliferation on the leavesrevealed meristematic areas at the surface of the basal swellingswith vascular connections to the underlying tissue. Using thesame culture conditions, adventitious shoots could be inducedfrom a range of grapevine cultivars incorporating several majorVitis species. Variations in the responses of the cultivarsCabernet Sauvignon and Sultana to the culture conditions aredescribed. The growth habits of plantlets derived from fragmentedshoot apices during culture and on subsequent transfer to theglasshouse are compared and discussed.