Somatic embryogenesis induction in Rosa persica Michx ex Juss.

Abstract

The current research aimed to evaluate the impact of various explants (immature zygote embryos, hypocotyls, and cotyledons), the effects of liquid and agar solidified MS media, as well as 2,4-D and BA on the induction and development of somatic embryos from Rosa persica. Although hypocotyls and cotyledon explants generated callus and primary globular embryos, only immature zygotic explants were able to produce mature somatic embryos in a half-strength liquid and agar- solidified MS medium. Indirect mature somatic embryos were only produced in agar-solidified MS media while liquid MS media-derived direct and indirect embryos could not further develop into mature embryo. Embryogenic callus induction mostly occcurred in half-strength MS media supplemented with 0.3 mg L^− 1 2,4-D or 0.09 mg L^− 1 BA and 0.3 mg l^− 1 2,4-D on half-strength MS liquid and agar-solidified media, respectively. Immature zygote embryos formed embryogenic calli at a success rate of 57.14% and 46% on half-strength MS agar-solidified and liquid media, respectively. Indirect Somatic embryogenesis was induced only from detached immature zygote explants, achieving a frequency of 25.11% and 9.64% in agar-solidified and liquid media, respectively. However, the concentration of PGR to induce the highest somatic embryo was different in liquid and agar-solidefied media. In liquid media, the incubation of explant for four weeks on half-strength MS media supplemented with 1 mg L^− 1 of BA and 0.9 mg L^− 1 2,4-D and then subculturing them in half-strength MS media supplemented with 1 mg L^− 1 of BA and 0.3 mg L^− 1 2,4-D resulted in the highest indirect somatic embryo (24.5 embryos per explant). The same MS media supplemented with 1 mg L^− 1 of BA and 0.09 mg L^− 1 2,4-D resulted in direct somatic embryo (4.3 embryos per explant). However, non of the somatic embryos could further germinate in liquid media. In agar-solidified media, the incubation of explants in half-strength MS media supplemented with 0.3 mg L^− 1 2,4-D during the induction phase and subsequent subculture of embryogenic callus on half-strength MS media supplemented with 1 mg L^− 1 of BA and 0.3 mg L^− 1 2,4-D resulted in the highest somatic embryo (26 somatic embryos per explant). The highest germination rate (46.15%) of somatic embryos occurred in PGR-free and agar-solidified MS media from 16-weeks-old embryogenic callus culture, which was primarily incubated in half-strength MS media supplemented with 0.3 mg L^− 1 2,4-D for four weeks and then subculturing them in half-strength MS media supplemented with 1 mg L^− 1 of BA and 0.3 mg L^− 1 2,4-D. The acclimatization efficiency of the acquired plantlets was 25%, and they could not grow vigorously in the greenhouse. The results of this experiment can help utilize wild relative Rosa species in breeding programs as a remarkable genetic resource to expand the accessible gene pool of new Rosa cultivars.