The effect of auxins, time exposure to auxin and genotypes on somatic embryogenesis from mature embryos of wheat

The effects of different factors on the embryogenesis and plant regeneration from mature embryos of Russian spring and winter genotypes were studied. Embryogenic callus induction was achieved on MS medium supplemented with different concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) or Dicamba (3,6-dichloro-o-anisic acid). Although all auxins were able to induce callus from explants with high frequency (98–100%), Dicamba was more effective for the induction of embryogenic callus (21.8–38.3%). Maximum embryogenic callus formation and high number of regenerated plants were observed at 12 mg l⁻¹ of Dicamba. The time exposure to Dicamba (7, 14, 21 and 28 days) had a significant effect on efficiency of somatic embryogenesis. When contact of explants with callus induction medium was increased from 7 to 21 days the rate of somatic embryogenesis and number of regenerated plants per embryogenic callus gradually increased from 13.0 to 38.4% and 3.6 to 8.0%, respectively. Supplement of additional auxins (indoleacetic acid (IAA), indolebutyric acid (IBA), and naphthaleneacetic acid (NAA)) to callus induction medium with Dicamba had a positive effect on the rate of embryogenic callus formation, while the average number of regenerated shoots was not affected. The best rate of somatic embryogenesis was observed at the addition of 0.5 mg l⁻¹ IAA with Dicamba (61.0%). The optimum combination of Dicamba and IAA increased the efficiency of somatic embryogenesis and plant regeneration from seven spring and winter wheat genotypes, thought overall morphogenic capacity was still genotype dependent.