Optimization of In Vitro Propagation of Pear (Pyrus communis L.) ‘Pyrodwarf®(S)’ Rootstock

Abstract

Pears are among the most economically important fruits in the world that are grown in all temperate zones. Pyrus communis L., ‘Pyrodwarf®(S)’ rootstock is one of the gene sources used to improve fruit productivity, rootstock resistance, and tolerance to biotic and abiotic stresses. Traditional propagation of P. communis L. is time-consuming and limited by a short growing season and harsh winter conditions. Therefore, in vitro propagation is a suitable alternative. Murashige and Skoog medium (MS) and woody plant medium (WPM) supplemented with different concentrations of 6-benzyladenine (BA) and kinetin (Kin), individually or in combination, were used for in vitro shoot proliferation. Nodal segments were used as explants. MS medium augmented with indole-3-butyric acid (IBA) or indole-3-acetic acid (IAA) was then used for rooting of microshoots. A combination of 2 mg·L−1 BA and 1 mg·L−1 Kin in MS medium resulted in a significant improvement in shoot proliferation. This combination produced the highest number of shoots (4.352 per explant) and leaves (10.02 per explant). The longest shoots (4.045 cm) were obtained in WPM enriched with 1 mg·L−1 BA. However, these shoots were not suitable for multiplication and rooting steps. The largest number of roots (5.50 per microshoot) was obtained on MS medium augmented with IAA at 1 mg·L−1. The produced plantlets were cultivated in pots filled with perlite and cocopeat (in a ratio of 1:3) and acclimatized gradually in a greenhouse, recording an even 90% survival rate.