Somatic embryogenesis of Torreya grandis ‘Merrillii’

Key words: 
• botany /
• Torreya grandis ‘Merrillii’ /
• embryogenic tissue /
• somatic embryogenesis /
• NAA

Abstract: To establish somatic embryogenesis protocols for Torreya grandis Merrillii，immature embryos were used as explants. The effects of different basal mediums （SH，MS，B5），organic additives （glutamine （Glu），casein hydrolysate （CH），myo-inositol），carbon sources （sucrose，glucose，maltose），and plant growth regulators （PGRs） （N6-benzylaminopurine （BA），Kinetin （KT），2，4-dichlorophenoxyacetic acid （2，4-D） or BA，KT，a-naphthaleneacetic acid （NAA） for the initiation of primary callus were tested. Optimal PGRs for induction and proliferation of embryogenic tissue were determined，and a study on somatic embryo induction （SH supplemented with 0.05 mgL－1 6-BA and 0.25 mgL－1 2，4-D，SH supplemented with 0.05 mgL-1 2，4-D and SH supplemented with 0.05 mgL-1 NAA respectively） and germination （SH supplemented with ABA or PEG） was carried out. Results showed that callus initiation frequency for SH supplemented with Glu was significantly higher （P ＜ 0.05） than other treatments，with 50.8%. The optimal carbon source was sucrose and the optimal concentration was 3%. To improve primary callus induction，an initiation medium containing a low concentration of 2，4-D or NAA was most efficient. The highest callus induction frequency was with SH medium and 0.1 mgL-1 NAA. For formation and proliferation of embryogenic tissue，the optimal medium was SH supplemented with 0.05 mgL－1 NAA. When callus was inoculated onto 1/2 SH medium supplemented with ABA and PEG 6000，somatic embryos were produced. Germination quality of somatic embryos was better with exposure to 1 200 lx light compared to in the dark.［Ch，3 fig. 3 tab. 21 ref.］