Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: July 10, 2006
Publication Date: October 10, 2006
Citation: Srinivasan, C., Scorza, R. 2006. The influence of genotype on the induction of somatic embryos from in vitro cultured zygotic embryos of peach. Acta Horticulturae. 738:691-696. Technical Abstract: Genotype-independent transformation of peach [Prunus persica (L.)] Batsch is difficult to achieve, primarily due to its high recalcitrance to plant regeneration in vitro. In spite of sporadic reports of adventitious regeneration from peach tissue cultures, there is no universal method of peach regeneration that can be reliably used for peach transformation. In order to determine the relationship between genotype and regenerative competence in peach, we excised 1-3 mm long immature zygotic embryos from 23 peach genotypes and cultured these on Raj Bhansali et al (Plant Cell Reports 9:280-284 1990) medium containing 2-4, dichloro phenoxy acetic acid (2,4-D) which was reported to induce somatic embryos from immature zygotic embryos. Somatic embryos were produced by all the 23 genotypes tested but the number of explants forming somatic embryo varied widely between genotypes. In general, younger zygotic embryos (1 mm) were more competent to form somatic embryos. Over all genotypes tested, 35% of one mm long zygotic embryos produced somatic embryos, whereas, only 27% of two mm and 16% of three mm long zygotic embryos produced somatic embryos. 'Belle of Georgia', 'Tennessee Natural', and 'Nemaguard' produced the highest rates of somatic embryo production. About 43 to 68% of zygotic embryos of these three genotypes produced somatic embryos. Besides 2,4-D, other synthetic auxins such as dicamba (3,6-dichlo-o-anisic acid) picloram (4-amino 3,5,6-trichloroapicolinic acid), and centrophenoxine also induced somatic embryogenesis from zygotic embryos of 'Encore' and 'Bailey'. Culture of immature zygotic embryos for one week in Murashige and Skoog (MS) medium + 5 uM 2,4-D medium and subculture onto MS + 12.5 uM thidiazuron sporadically induced shoot regeneration.