Optimization of direct somatic embryogenesis induction and plantlet regeneration in European Pear

To evaluate somatic embryogenesis (SE) induction, mature, immature cotyledon and endosperm explants of Natanzi, Ghosi, Dar Gazi, and Williams cultivars obtained from 40-100 days after pollination were cultured into the White, SH, and MS media containing (2.3, 9 and 18 µM) 2, 4-D. Then, to enhance the efficiency of direct SE, Ghosi cultivar endosperm, the preferable explant was known in before experiment, was cultured in MS medium with hormonal treatments consisted of 2,4-D (0-2 µM) and TDZ (0-9 µM). To germinate and plant recovery, MS medium with different treatments consisted of control, 150 mg/L Fe-EDDHA, 2 mg/L AgNO3, and 1mg/L GA3 were used. Finally, for plant adaptation, two successive experiments, the effect of mycorrhizae at 0 and 0.25 g/Kg levels and the comparison of two fertigation procedures, were separately carried out. The results revealed, the only endosperm of Ghosi cultivar in MS medium produced direct somatic embryos. 0.5 µM 2,4-D had the highest frequency of somatic embryos production (12.66%). The highest frequency of normal embryo obtained in 0.5 µM 2,4-D (71%) and 0.5 µM 2,4-D + 4.5 µM TDZ (70%). The highest germination (9.66%) and plant recovery (12%) obtained in Fe-EDDHA. In the adaptation phase, the usage of mycorrhizae and the second procedure of fertigation were known preferable. Overall, the method presented in this study can be used in molecular studies of this cultivar.