Comparative and Expression Analysis of Ubiquitin Conjugating Domain-Containing Genes in Two Pyrus Species.

Ripening affects the nutritional contents and quality of fleshy fruits, and it plays an important role during the process of fruit development. Studies have demonstrated that ubiquitin-conjugating (<italic>UBC</italic> or <italic>E2</italic>) genes can regulate fruit ripening, but the characterization of <italic>UBCs</italic> in pear is not well documented. The recently published genome-wide sequences of <italic>Pyrus bretschneideri</italic> and <italic>Pyrus communis</italic> have allowed a comprehensive analysis of this important gene family in pear. Using bioinformatics approaches, we identified 83 (<italic>PbrUBCs</italic>) and 84 (<italic>PcpUBCs</italic>) genes from <italic>P. bretschneideri</italic> and <italic>P. communis</italic>, respectively, which were divided into 13 subfamilies. In total, 198 <italic>PbrUBC</italic> paralogous, 215 <italic>PcpUBC</italic> paralogous, and 129 orthologous gene pairs were detected. Some paralogous gene pairs were found to be distributed on the same chromosome, suggesting that these paralogs may be caused by tandem duplications. The expression patterns of most <italic>UBC</italic> genes were divergent between <italic>Pyrus bretschneideri</italic> and <italic>Pyrus communis</italic> during pear fruit development. Remarkably, the transcriptome data showed that <italic>UBC</italic> genes might play a more important role in fruit ripening for further study. This is the first report on the systematic analysis of two <italic>Pyrus UBC</italic> gene families, and these data will help further study the role of <italic>UBC</italic> genes in fruit development and ripening, as well as contribute to the functional verification of <italic>UBC</italic> genes in pear. [ABSTRACT FROM AUTHOR]