Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: December 1, 2006
Publication Date: March 15, 2007
Citation: Srinivasan, C., Scorza, R. 2007. 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 produce adventitious 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 relative efficacy of regenerative competence in peach, we excised one to three mm long immature zygotic embryos from 25 peach and nectarine genotypes, and cultured on Raj Bhansali et al (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 from 23 peach and nectarine genotypes, but the number of explants forming somatic embryos varied widely between genotypes. In general, the younger the zygotic embryos are, the more competent it is to form somatic embryos. Accordingly, one mm long zygotic embryos are more regenerative than two or three mm. Thirty-seven percent of one mm long zygotic embryos produced somatic embryos, whereas, only 27 percent of two mm and 16 percent of three mm long zygotic embryos produced somatic embryos. High percentage of zygotic embryos extracted from 'Bell of Georgia', 'Bailey', 'Tennessee Natural', and 'Nemaguard' produced somatic embryos as compared to other genotypes. Besides 2,4-D, other synthetic auxins, such as dicamba (3,6-dichlo-o-anisic acid) picloram (4-amino 3,5,6-trichloroapicolinic acid), centrophenoxine (4-chlorophenoxyacetic acid 2-dimethylaminoethyl ester) also induced somatic embryogenesis from zygotic embryos of 'Encore'. One week preculture in the dark of five to seven mm long cotyledons excised from immature zygotic embryos on MS (Murashige and Skoog 1962) medium + 5 uM 2, 4-D + 0.5 uM benzyladenine (BA) followed by subculture onto MS + 12.5 uM thidiazuron (TDZ) + 0.4 uM alpha Naphthaleneacetic acid (NAA) induced adventitious shoot regeneration under light in peach genotypes 'Bounty' and 'Bailey'.