An optimized protocol for in vitro propagation of Pyrus communis and Pyrus syriaca using apical-bud microcuttings

Purpose: In Tunisia, pear cultivars are widely threatened by the attack of fire blight disease. Cultivation of tolerant cultivars is an effective control strategy for disease control. For this purpose, a reliable protocol was established for micropropagation of local Pyrus communis and Pyrus syriaca L. and for large-scale production of high-quality plantlets. Research method: Using apical explants, different media and hormones were tested to establish a micropropagation procedure for local Tunisian Pyrus communis cultivars ‘Arbi’, ʻMaltiʼ, ʻMahdia 6ʼ and ʻMoknine 10ʼ and for Pyrus syriaca. Disinfection with 4% HgCl2 treatment for 20 minutes showed the highest percentage of plant survival. Successful initiation of the cultures was achieved on MS basal medium supplemented with 0.25 mg L-1 BA. Findings: During the proliferation stage, optimal shoot multiplication was obtained on MS medium with a half concentration of NH4NO3 and KNO3 supplemented with 0.1 mg L-1 IBA and 2 mg L-1 BA, but for maximum shoot length the BA concentration needed to be lowered to 1 mg L-1. A rooting rate of 100% and the highest root length and root number were attained on Cheng medium supplemented with 1.0 mg L-1 IBA. Pear vitroplants were successfully acclimatized on S2 substrate, composed by peat moss. Research limitations: Vitroplants acclimatization step needs to be well studied for the improvement of theacclimatized vitroplant survival rates by reducing the symptoms of crown rot. Originality/Value: This efficient optimized in vitro protocol will be successfully applied for large multiplication of high quality of Tunisian Pyrus vitroplants and cultivars.

Keywords:

acclimatization , apical explants , growth regulators , micropropagation , Tunisian pear cultivars