S04 - Session P1 - New Tools II - In vitro regeneration, via organogenesis, from leaves of the peach rootstock GF677 (P. persica x P. amygdalus)

Authors: Angela Ricci *, Silvia Sabbadini, Oriano Navacchi, Lorenzo Burgos, Bruno Mezzetti

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 ( P. persica x P. amygdalus ). Basically, expanding leaves from elongated in vitro shoot cultures were placed in several regeneration media consisting of McCown Woody Plant Medium (WPM) as a 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 α-naphtalene acetic acid (NAA) or 2, 4-Dichlorophenoxyacetic acid (2, 4-D). Despite the results obtained from the experiments showed the low efficiency of this adventitious shoot regeneration system, adventitious shoot regeneration was observed and 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 obtainment of plants through somatic embryogenesis of peach rootstocks and cultivars is arduous to date.