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

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 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. 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.