Copper nanoparticles enhanced surface disinfection, induction and maturation of somatic embryos in tuberous begonias (Begonia x tuberhybrida Voss) cultured in vitro

The sterilization effectiveness of copper nanoparticles (CuNPs) replaced common disinfectants such as mercury chloride (HgCl2) or calcium hypochlorite (Ca(ClO)(2)) on different explants (petioles-P, inflorescence-F and stem nodes-S) of ex vitro tuberous begonias (Begonia x tuberhybrida Voss) was investigated. Subsequently, the P, F and S explants were cut transversely into thin cell layer (tTCL) approximately 1 mm in length (P-tTCL, F-tTCL and S-tTCL) and cultured on SE induction medium in order to investigate the effect of disinfectants on somatic embryogenesis, somatic embryo morphology, antioxidant activity (Catalase-CAT and Ascorbate Peroxidase-APX), and carbohydrate content (sugar and starch) of somatic embryos and their subsequent growth. The results showed that CuNPs can replace HgCl2 and Ca(ClO)(2) and are effective in surface disinfection of P, F and S explants. CuNPs enhanced embyrogenic callus and somatic embryogenesis of treated explants compared to those on HgCl2 and Ca(ClO)(2). CuNP-treated F-tTCL and S-tTCL explants recorded the highest number of somatic embryos (38.00-36.67 embryos, respectively) as well as the percentage of somatic embryos in cotyledon-shape (47.37-49.09%, respectively). Moreover, the antioxidant enzyme activity (CAT and APX) and starch content of somatic embryo clusters derived from CuNPs-treated F-tTCL and S-tTCL explants were higher and the sugar content was lower as compared to those sterilizated with HgCl2 or Ca(ClO)(2). Plantlets derived from different different disinfectant treatments showed no difference in morphology, in vitro rooting and acclimatization stages in the greenhouse. Key message Surface disinfection efficiency of CuNPs on ex vitro begonia explants compared to those of common disinfectants. CuNPs effected on somatic embryogenesis, antioxidant activity, carbohydrate content.