The pear (Pyrus communis L.) is a typical fruit of temperate regions, having its origin and domestication at two different points, China and Asia Minor until the Middle East. It is the fifth most widely produced fruit in the world, being produced mainly in China, Europe, and the United States. Pear belongs to rosaceous family, being a close "cousin" of the apple, but with some particularities that make this fruit special with a delicate flavor. Thus, it deserves a special attention and a meticulous review of all the history involved, and the recent research devoted to it, because of the economic and cultural importance of this fruit in a range of countries and cultures. Therefore, the purpose of this literature review is to approach the history of the origin, domestication, and dispersal of pears, as well as reporting their botany, their current scenario in the world, and their breeding and conservation.

RESUMOObjetivou-se estudar a composição de diferentes meios de cultura, concentrações de BAP e tipos de explante, na multiplicação in vitro do porta-enxerto 'GxN-9', como também a influência desses fatores na ocorrência de vitrificação. Explantes basais cultivados em meio QL e WPM apresentaram as melhores respostas para porcentagem de brotação (80%). O número de brotações por explante também foi maior com explantes basais, porém apenas aqueles cultivados no meio QL (3 brotações por explante). Os meios QL e WPM permitiram obter o melhor desempenho de crescimento das brotações formadas, para ambos os tipos de explante. Contudo, explantes basais cultivados em meio QL, apresentaram 55% de vitrificação, ao passo que explantes provenientes do meio WPM, não apresentaram esta anormalidade. Concluiu-se que a redução na concentração de sais com adição de 0,5 mg dm -3 de BAP reduz a vitrificação, promovendo aumento no crescimento das brotações, sem influenciar na formação das mesmas.Palavras-chave: Produção de mudas; pessegueiro, in vitro, citocinina; vitrificação. ABSTRACTThe objective of the present work was to study the composition of different culture medium, BAP concentration and explants types on in vitro multiplication of the rootstock 'GxN-9', like the influence of this factors in the vitrification. Basal explants cultivated in QL and WPM medium had the better results regarding shooting percentage (80%). The shoot number per explants was also higher with basal explants when cultivating in QL medium (3 shoot a explant). The medium QL and WPM allowed better growth performance of formed shoots to both explants types. Nevertheless, basal explants cultivated in QL medium had 55% of vitrification, whereas explants from WPM medium did not show this abnormality. The lower level of salt concentration with 0.5 mg dm -3 BAP reduced vitrification, promoting an increase in shoot growth without affecting formation rates.