Organogenesis of stem and leaf protoplasts of a haploid golden delicious apple clone (Malus Xdomestica Borkh.).

Highly viable protoplasts were isolated in large numbers from in vitro-grown leaf and stem tissues of a haploid clone of the apple scion cultivar Golden Delicious (Malus Xdomestica Borkh.). Protoplasts from both sources divided rapidly to give microcallus, when cultured in a modified Kao and Michayluk-based medium. Following two successive subcultures for callusing, shoot buds were regenerated from such calli, on half-strength Murashige and Skoog medium with an increased concentration of group B vitamins and containing 5.0 mg.l(-1) 6-benzyl-aminopurine and 0.1 mg.l(-1) l-naphthaleneacetic acid (for the leaf protoplast-derived calli) or 4-indole-3yl-butyric acid (for stem protoplast-derived calli). The mesophyll protoplast-derived shoots were enfeebled and vitrified, in time with their ultimate death. Conversely, for those shoots deriving from the stem protoplasts, in vitro propagation was successfully achieved. This is the first report on the successful isolation, culture and organogenesis from stem protoplasts of a woody plant genotype.

An extensive hairy root production precedes shoot regeneration in protoplast-derived calli of cauliflower (Brassica oleracea var. botrytis).

Protoplasts isolated from mesophyll tissues of cauliflower (Brassica oleraceavar. botrytis) were induced to divide in culture, with 2% of them producing calli. Upon transfer to a regeneration medium containing a low auxin/cytokinin balance (0.02mg/l 1-naphthaleneacetic and 2mg/l 6-benzylaminopurine), they displayed an extensive production of hairy roots before the regeneration of shoots. Negative effects of root differentiation on the subsequent caulogenesis by such calli were not observed, since 97% of the calli regenerated hairy roots and 93% gave shoots.

A protoplast-to-plant system in chrysanthemum: differential responses among several commercial clones.

Plant regeneration has been obtained from Chrysanthemum mesophyll protoplasts. Of the twenty-nine clones studied, division was observed for eighteen clones, and coupled with colony formation for sixteen of them. Elimination of NH4NO3 from the culture medium greatly improved colony survival in culture. Calli were obtained from colonies of five clones, and for clone n(o) 42 buds were produced. Regeneration ability, for such protoplast-derived calli of clone n(o) 42, was retained over a prolonged culture period. The regenerated plants were successfully transferred to the glasshouse (4 to 5 months from protoplast isolation).