Morphogenesis of isolated floral buds of Ranunculus sceleratus L. in vitro

Morphogenesis of floral buds excised at various stages of development was followed in vitro. The buds comprising the primordia of sepals and stamens (Stage I) failed to complete normal development on any of the nutrient media tried. However, the initiation and further development of carpels occurred even on a medium containing mineral elements, glycine, vitamins and sucrose. On the other hand, the buds having the anthers at the pollen mother cell stage (Stage II) completed microsporogeriesis and 2-ceIled pollen grains were formed in the anthers. The torus i.e. the central dome bearing the carpels, of Stage II, and III (buds having anthers at pollen grain stage) elongated enormously and emerged through the folded sepals. Regeneration of roots and shoot buds (especially in Stage II & III buds) was common. In addition, the floral buds of all stages formed callus which subsequently differentiated roots, shoot buds and embryoids leading to the formation of plantlets. The latter, in turn, developed embryoids from the epidermal and pith cells of the stem. On subculturing, the hypocotyl portion of the in vitro plantlet was capable of developing embryoids directly from the epidermal cells, whereas the radicular and plumular portions of the same plantlet first formed callus and subsequently embryoids. The growth of callus and the differentiation of embryoids could be maintained through repeated subculturing. Embryoids could be induced even on a simple medium having only mineral elements and sucrose. Among the several growth adjuvants used, a combination of coconut milk and IAA supported best callus growth and normal embryoid differentiation.