EFFICIENT SHOOT REGENERATION SYSTEM OF PEAR ROOTSTOCK OHF 333 (PYRUS COMMUNIS L.) LEAVES

Abstract

The pear rootstock OH × F (P. communis L.), bred in the USA, shows 10% more vigorous growth compared to BA29, but it has a slower growth than the seedlings of ‘Williams’. The rootstock is characterized by high yield efficiency and moderate resistance to fire blight (Erwinia amylovora). Some clones of OH × F are difficult to propagate, that is why they are propagated in vitro. The aim of the present research was to develop an efficient system for shoot regeneration from pear rootstock OHF 333 leaf explants and to investigate the effect of plant growth regulators on the regeneration capacity. Studies were carried out with leaf segments of in vitro propagated plants of OHF 333 (P. communis L.) cultivar. Leaf segments of the source plants were cultivated on nutrient media for regeneration based on Murashige and Skoog (MS) with added TDZ (thidiazuron, 7.5 and 9μM), 2.46 μM indole-3-butyric acid (IBA), 10 g/L sucrose, 30 g/L sorbitol and different indole acetic acid (IAA) content - 5, 10, 15 and 20 μM. The explants were cultivated in darkness for 15 days, after which at a photoperiod of 16/8 hours (40 μmol m -2 s -1 PPFD) at a temperature of 22±2°C for 20 days. The best efficiency of somatic organogenesis (over 80% regeneration and more than 5 regenerants per explant) was achieved on two nutrient media - with 7.5 μM TDZ, 2.46 μM IBA and 20 μM IAA or with 9 μM TDZ, 2.46 μM IBA and 10 μM IAA. All the regenerants obtained were cloned, propagated and would be tested for resistance to fire blight (Erwinia amylovora) after acclimatization.