In vitro propagation of cauliflower, Brassica oleracea var. botrytis for hybrid seed production

Methods for obtaining heterotic F-1 and maintaining purebred lines for bree ding of Brassica oleracea are limited by absence of male sterile lines and occurrence of inbreeding depression, respectively. The use of vegetative (s tem, petiole, leaf, leaf rib) and floral (peduncle, pedicel, flower bud, cu rd) explants of cauliflower to regenerate purebred lines for crossing were examined. Of four growth regulator treatments and explant types used, best results were obtained with curd explants on MS medium with 6-benzyladenine (cytokinin) and gibberellic acid. Although 6-benzyladenine alone promoted f ormation of shoots in floral explants, both 6-benzyladenine and alpha-napth aleneacetic acid were required for vegetative explants. Use of alpha-naptha leneacetic acid, however, often increased callus formation. These culture t echniques to maintain purebred regenerated plants will complement newly-der ived nuclear-based male sterile lines obtained by the introduction of antis ense copies of the gene BcpI, which is required for pollen fertility.