Efficient callus induction and plantlets regeneration in durum wheat using mature embryos

Abstract

The use of mature embryos as explants to initiate cultures is a best alternative to save time and costs, especially for producing somatic embryos for genetic transformation of durum wheat. However, plantlets regeneration from cultures derived from matured embryos is usually low. In this study, we tested matured embryos as explants from eight Moroccan durum wheat varieties (‘Irden’, ‘Marzak’, ‘Kyperounda’, ‘Isly’, ‘Amria’, ‘Karim’, ‘Marouane’ and ‘Tomouh’) to define suitable culture media for obtaining high frequencies of somatic embryogenesis and in vitro plantlets regeneration. For this purpose, we tested five induction and maintenance media (M1 to M5) based on MS media (macro and oligo-elements) which differed with respect to concentrations of plant hormones (2,4-D and BA), vitamins, sucrose, maltose, L-asparagine, and solidifying agents. All tested media induced embryogenic callus for the varieties and regenerate plantlets. However, a significant effect of variety, medium and variety × medium interaction were observed for callus induction and regeneration. Average callus growth as measured by relative fresh weight growth rate (RFWGR) across different media was the highest for ‘Amria’ (7215.4%) and the lowest for ‘Tomouh’ (2088.2%). M1 (2 mg/L 2,4-D) and M5 (3 mg/L 2,4-D) media gave highest RFWGR(6892.1% and 6332%, respectively) and M3 (1 mg/L 2,4-D) was the lowest (3708.8%), across different varieties. However, the embryogenic callus from M3 media regenerated the highest percentage of plantlet, upon transfer to regeneration medium, for most of the varieties. For the varieties ‘Marouane’, ‘Kyperounda’, ‘Marzak’, ‘Karim’, and ‘Tomouh’, the favourable medium was M3, whereas, for ‘Isly’, ‘Irden’ and ‘Amria’, both M2 (2.5 mg/L BA and 2.5 mg/L 2,4-D) and M3 were the favourable media for embryogenic callus induction. In this study, for the first time, favourable media for induction and regeneration from mature embryo of Moroccan durum wheat varieties were identified. These media will be used for callus induction and genetic transformation.