Development of an efficient regeneration protocol for pear rootstock pyrodwarf and assessment of ssr variability in regenerating shoots

Abstract

The use of biotechnological methods is of particular interest in fruit tree crops since conventional breeding programs require long time and high resources before having impact upon commercialization. To develop an efficient plant regeneration protocol for pear rootstock Pyrodwarf, different combinations of two hormones, naphthalene-1-acetic acid (NAA) and Thidiazuron (TDZ) were studied on regeneration process. Other factors were also studied, such as darkness period and the use of different hormone concentrations during induction and expression phase. Our experiments showed that the length of darkness did not affect in vitro regeneration. Different concentrations of TDZ have different effects on regeneration: 6 μM has been shown to be more effective than 2.5 μM. A higher level of TDZ during induction period was the only important factor to induce regeneration independently to the presence of hormones during expression phase. The two hormones showed to be uneffective to induce a sufficient number of regenerating shoots from leaf explants of another pear rootstock, Fox11. Variability during regeneration was assessed using SSR markers. An identical genetic profile was observed between in vitro explants and regenerating shoots. These results are useful to include Pyrodwarf in genetic engineering experiments for breeding purposes. On the contrary, other hormones have to be evaluated for their effectiveness to induce in vitro regeneration in Fox11 leaf explants. © 2009 Taylor & Francis Group, LLC.