In Vitro Regeneration, Via Organogenesis, from Leaves of the Peach Rootstock GF677 (P. Persica × P. Amygdalus)

The optimization of an efficient in vitro adventitious shoot regeneration protocol represents a key step for the application of biotechnological approaches aimed to genetically improve P. persica L. rootstocks and cultivars. However, peach is well-known as one of the most recalcitrant fruit trees species in terms of in vitro regeneration, especially when adult tissues are used as starting explants. The present study represents the first successful attempt to induce adventitious regeneration from leaves of the peach rootstock GF677 (Prunus persica L. x P. amygdalus L.). Basically, expanded leaves from elongated in vitro shoot cultures were placed in different regeneration media consisting of McCown Woody Plant Medium (WPM) as basal salt, supplemented with different combinations and concentrations of plant growth regulators (PGRs). In this study, low regeneration rates (from 2% up to 12%) were recorded when leaf explants of GF677 were cultured on regeneration media enriched with thidiazuron (TDZ) used alone or in combination with a-naphtalene acetic acid (NAA), or 2,4-dichlorophenoxyacetic acid (2,4-D). Although at low percentage, adventitious shoot regeneration was observed in this study, and the preliminary results obtained can be considered as promising starting point for further studies aimed to increase the percentage of in vitro organogenetic explants of this important commercial genotype. In conclusion the establishment of efficient regeneration method through organogenesis for the peach hybrid rootstock GF677 might represent a step forward for genetic improvement of P. persica L., as the production of plants through somatic embryogenesis of peach rootstocks and cultivars has been arduous to date.