Influence of Zeatin on Wheat Regeneration from Immature Embryos

Sa？etak Immature embryo culture of nine Croatian winter wheat genotypes were performed in order to determine the influence of zeatin, as an exogenous growth regulator, on regeneration capacity of callus and number of regenerated shoots. Immature embryos 0.5-1.5 mm in size were aseptically isolated and plated with the scutellum exposed on modified MS medium containing MS salts and vitamins supplemented with 2 mg/l 2,4-D (2,4-dichlorophenoxyacetic acid) and 30 g/l sucrose. For shoot initiation, calli were transferred on two different regeneration media: MSZ0 medium (MS salts and vitamins supplemented with 0.2 mg/l 2,4-D and 30 g/l sucrose) and MSZ5 medium (MS salts and vitamins supplemented with 0.2 mg/l 2,4-D, 5 mg/l zeatin and 30 g/l sucrose) and incubated at 26°C with 16/8 h light/dark photoperiod. Mean regeneration capacity of callus was higher on MSZ5 medium compared to MSZ0 medium (48.0% and 33.6% respectively). For all genotypes, except Lipa, regeneration capacity of callus was higher on MSZ5 medium. However, mean number of regenerated shoots was similar on MSZ5 compared to MSZ0 medium (1.6 and 1.3 respectively). The highest number of regenerated shoots per callus induced was found for genotype ？itarka (4.39), followed by genotypes Barbara (2.76), Lipa (2.61), line ZG1 (2.04) and Edita (1.67)