Cytokinins and the Regeneration of Plantlets From Secondary Embryoids of Winter Oilseed Rape, Brassic a Nap Us Ssp. Oleifera

SUMMARY It was shown that only a small proportion of haploid (= amphihaploid; n= 19) secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera) grew into plants when transferred to a medium without plant growth regulators. The majority grew abnormally and formed further secondary embryoids on their surfaces. It was then found by experiment that an effective method of inducing leaf initiation and reducing secondary embryogenesis was to transfer the secondary embryoids to a basal medium supplemented with 6‐furfurylaminopurine (kinetin; 10−4 M), alone or in combination with low concentrations of indole‐3‐acetic acid. Roots were initiated by further transfer of the cultures to basal medium without plant growth regulators. The plantlets so produced were normally haploid and were suitable for growing on into whole plants. The reduction of secondary embryogenesis by cytokinins is discussed in the general context of response by plant tissues to plant growth substances.