Effect of stress factors on somatic embryogenesis of rose

Abstract

In the present study, somatic embryogenesis was optimized in three cut-flower roses including Rosa hybrida 'Full House', 'Ocean Song' and 'Maroussia'. Stress factors including ABA, NaCl, reduction in sucrose concentration, different concentrations of NAA or 2,4-D were applied. In order to detect ploidy changes in the regenerated somatic embryos, the ploidy level of the regenerants and their donor plants were assessed by flow cytometry. The results indicated that somatic embryogenesis was highly genotype dependant. The highest induction rate of embryogenic calli (46.66%) and number of primary and secondary embryo (7.33 and 116.66) were obtained in 'Ocean song' in MS medium supplemented with NAA (3 mg l -1 ) in combination with 300 mg l -1 proline. Moreover, application of 100 mg l -1 NaCl as stress factor along with 2 mg l -1 2, 4-D resulted in high rate of somatic embryogenesis (40.0%) in 'Ocean song'. The highest rate of somatic embryogenesis ( 26.66%) in Rosa hybrida cv. Maroussia in MS medium with 1.5 mg l -1 2, 4-D and 0.1 mg l -1 ABA and Full House with 0.5 mg l -1 2, 4-D along with half sucrose concentration were observed. In all experiments, hormone-free MS medium were used for production and proliferation of secondary somatic embryos from primary embryos. Our results suggest that stress agents have an important role in the cellular mechanisms conducting somatic embryogenesis induction in rose, and that the ploidy level of the regenerated plants remains unchanged.