Adventitious shoot formation on excised hypocotyls of Antirrhinum majus L-(Snapdragon) in vitro

Hypocotyls from Antirrhinum majus L. were excised at 2 weeks of age from se edlings grown under a 16-hour photoperiod or continuous darkness. Explants were cultured on modified Murashige-Skoog (MS) medium containing 0, 0.44, 2 .22, 4.44, 8.88, or 44.4 mu M BA to investigate adventitious shoot formatio n. Excised hypocotyls from eight commercial cultivars, three inbred lines, and an F-1 hybrid between two of the inbreds were cultured on MS medium con taining 2.22 mu M BA to assess genotypic effects on adventitious shoot form ation. The influence of seedling age was assessed by excising hypocotyls fr om seedlings at 6, 10, 14, 18, 22, 26, or 30 days. Optimal conditions for a dventitious shoot formation on excised hypocotyls included: seedling growth in a lighted environment, use of hypocotyls from 10-day-old seedlings, and culture on medium containing 2.22 mu M BA for 3 weeks. Under these conditi ons, up to a 5-fold improvement in number of shoots per hypocotyl over prev ious studies was achieved. Adventitious shoot formation was genotype-depend ent and appeared to be a dominant trait. Chemical name used: N-6-benzyladen ine (BA).