Enhancing the efficiency of somatic embryogenesis and plant regeneration system of sunflower (Helianthus annuus)

Somatic embryogenesis and shoot regeneration were determined for three sunflower (Helianthus annuus L.) geno-types, 10A, PI441983 and Aguara 6, using three somatic embryo induction media (EIM), EIM1, EIM2 and EIM3, and four shoot regeneration media (SRM), SRM1, SRM2, SRM3 and SRM4. Genotypes exhibited differential responses to both EIM and SRM. The highest percentage of somatic embryo formation was found when Aguara 6 (88.29 %) and PI441983 (42.00 %) were cultured on EIM2, containing 20 g/L sucrose, 10 g/L maltose, 100 mg/L glutamine, 100 mg/L proline, 100 mg/L casein hydrolysate, 100 mL/L coconut water, 1 mg/L 1-naphthalene acetic acid (NAA) and 1 mg/L thidiazuron (TDZ), while the best response in 10A (42.54 %) was observed on EIM1, containing 20 g/L sucrose, 10 g/L maltose, 5 g/L potassium nitrate (KNO3), 1 mg/L NAA and 1 mg/L 6-benzyladenine (BA). Interaction between genotypes and EIM also influenced shoot regeneration from somatic embryos. Somatic embryos which were induced with EIM0 (control) and EIM1 regenerated well into shoots in all SRMs. The best shoot regeneration percentage for Aguara 6 (85.27 %) and 10A (80.00 %) was achieved when somatic embryos were induced with EIM1 and subsequent shoot regeneration was induced with SRM1, containing 20 g/L sucrose, 10 g/L maltose, 5 g/L KNO3, 0.5 mg/L NAA and 1 mg/L BA. However, PI441983 showed the best shoot regeneration when somatic embryos were induced with EIM0, and shoot regeneration was induced with SRM0 (control), containing 30 g/L sucrose, 5 g/L KNO3, 0.5 mg/L NAA and 1 mg/L BA (55.56 %). Our results show that this improved regeneration system allows shoot regeneration to occur with a high frequency within 2 weeks.