PLANT-REGENERATION AND CALLUS TYPE IN BARLEY - EFFECTS OF GENOTYPE AND CULTURE-MEDIUM

To facilitate practical application of in vitro genetic manipulation to barley (Hordeum vulgare L.), methods for the in vitro culture of barley must be improved. Fifteen genotypes of barley, primarily cultivars or elite breeding lines adapted to North America, were examined for their ability to form regenerable callus from immature embryos on modified versions of MS, BS, and CC media. Regenerable calli were obtained from all genotypes. The frequency of embryogenic callus induction, the morphology and friability of embryogenic calli, the relative growth rate of embryogenic calli, and regenerability were influenced by genotype, culture medium, and genotype X culture medium interactions. Callus cultures that were embryogenic in appearance frequently were not regenerable, or regenerated only albino plantlets. The majority of green plants grown to maturity were fertile and normal in appearance. Genotype was the most important determinant of the in vitro response. Regenerability was transient for all genotypes, with few exceptions. The best in vitro performance, based on ability to form friable, regenerable callus, was observed for 'Golden Promise', 'Hector', 'Piroline', and 'Klages'.