Micropropagation of pear (Pyrus spp.): A review

In pear, micropropagation was achieved for the first time in 1979 on pear rootstock ‘OH × F 51’ and scion variety ‘Bartlett’. Significant progress has been made in the different areas of in vitro culture of pear since these first reports. In most cases, Murashige and Skoog (MS) revised medium (1962) was used as mineral medium for culturing many Pyrus species and cultivars for regeneration and/or proliferation, subculturing and subsequent rooting. The lower concentration of major elements in WPM (Woody Plant Medium; Lloyd and McCown, 1980) was more suitable for micropropagation of some pear genotypes. Starting material for establishment of pear in vitro culture consists mostly of shoot tips or single node explants from grafted plants. BAP is the most frequently used cytokinin for pear micropropagation. Exogenous auxins do not promote axillary shoot proliferation, however, culture growth may improve by their presence. Rooting Pyrus spp. in vitro has proven difficult, and scion cultivars have proved more difficult to root than rootstocks. However, several authors were successful in rooting European pears, but the results were poorer with Asian pears. NAA is mostly used for inducing rooting followed by IBA, IAA and 2, 4-D. Brief exposure of shoots to auxin and darkness followed by their transfer to hormone free medium resulted in good rooting response in pear. The success of transplanting and survival of plants greatly depends on the quality of roots. In pear, acclimatization has been accomplished in various substrates by progressively decreasing the relative humidity.