Abstract
Cotyledon explants of rape were excised from aseptically germinated seedlings and cultured during 2 weeks on M u r a s h i g e and S k o o g medium supplemented with auxins, cytokinins, auxin-cytokinin combinations and abscisic acid. Callus formation occurred on medium with 2,4-dichlorophenoxyacetic acid (2,4-D), naphthalene-l-acetic acid (NAA), indole-3-acetic acid (IAA) and on their combinations with kinetin (K) or 6-benzylaminopurine (BAP). Regeneration of roots was achieved on media with NAA, IAA and indole-3-butyric acid (IBA) and on combinations of these auxins with cytokinins. The presence of 2,4-D in the medium, though it promoted compact callus growth, had an inhibitory effect on root formation. Callus derived from the cotyledons had somewhat different requirements for growth in subculture and the root formation ability diminished in the course of the culture. Lower ABA concentrations stimulated callus growth whereas higher concentrations inhibited it similary as in the case of cotyledons. Shoot buds regenerated from the cotyledons after ca. 3 weeks on media supplemented with NAA + BAP. The 9-week-old plantlets transferred to the soil developed into complete plants. The plants which underwent vernalization formed flowers and normal seeds.
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