Pyrus pyrifolia, which is famous for its delicate flesh, is the most widely cultivated oriental pear. Stone cell content is an important factor affecting P. pyrifolia fruit quality. However, the mechanism underlying stone cell development remains to be fully elucidated. In this study, the content and distribution of stone cells of two cultivars of P. pyrifolia, namely, ‘Twentieth Century’ (TC) and its bud variety ‘Golden Twentieth Century’ (GTC), were compared. Results showed that the contents of stone cells and lignin in TC were significantly higher than those in GTC during the entire fruit development process. Moreover, fruits that developed 60 days after flowering had the highest stone cell content. By transcriptome sequencing, 1558 differentially expressed genes (DEGs), including 530 upregulated genes and 1028 downregulated genes, were identified. Gene Ontology (GO) enrichment analysis indicated hemicellulose metabolic process (GO: 0010410), lignin metabolic process (GO:0009808) and lignin catabolic process (GO: 0046274) were highly active in stone cell development. Kyoto Encyclopedia of Genes and Genomes metabolic pathway enrichment analysis suggested that in phenylpropanoid biosynthesis (ko00940) pathway, two enzymes (glucosyltransferase [EC:2.4.1.111] and peroxidase [EC:1.11.1.7]) could be important factors of lower lignin content in GTC than TC. The quantitative real-time polymerase chain reaction was used to screen out several genes and TFs, such as peroxidase 42-like gene, vinorine synthase-like gene, and Myb4-like TFs, are likely associated with stone cell development. Our study would provide a basis for the molecular mechanisms of stone cell development in P. pyrifolia cultivars and would aid in improving quality of pear fruits by breeding.

Pyrus pyrifolia以果肉细腻着称，是栽培最广的东方梨。石细胞含量是影响P. pyrifolia果实品质的重要因素。然而，石细胞发育的机制仍有待充分阐明。本研究中，P. pyrifolia两个品种的石细胞含量和分布，即，“二十世纪”（TC）及其芽品种“黄金二十世纪”（GTC）进行了比较。结果表明，在整个果实发育过程中，TC中石细胞和木质素的含量均显着高于GTC。此外，开花后 60 天发育的果实的石细胞含量最高。通过转录组测序，鉴定出1558个差异表达基因（DEGs），包括530个上调基因和1028个下调基因。基因本体（GO）富集分析表明，半纤维素代谢过程（GO：0010410）、木质素代谢过程（GO：0009808）和木质素分解代谢过程（GO：0046274）在石细胞发育中高度活跃。京都基因和基因组百科全书代谢途径富集分析表明，在苯丙烷生物合成 (ko00940) 途径中，两种酶（葡萄糖基转移酶 [EC:2.4.1.111] 和过氧化物酶 [EC:1.11.1.7]）可能是降低木质素含量的重要因素。 GTC 比 TC。定量实时聚合酶链反应被用来筛选几个基因和TFs，如过氧化物酶 42 样基因、长春碱合酶样基因和Myb4 样TF 可能与石细胞发育有关。我们的研究将为梨梨品种石细胞发育的分子机制提供基础，并有助于通过育种提高梨果实的品质。