Salicylic acid (SA) is known to be an efficient elicitor of secondary metabolism in plants. Arbutin, a characteristic phenolic glycoside found in ‘Yuluxiang’ pear (Pyrus bretschneideri Rehder × Pyrus sinkiangensis Yu), is widely used in lightening agents, in addition to cough, anti-inflammatory, and anti-microbial remedies, among other applications. However, research into the synthesis of arbutin in pear is limited. This study aimed to clarify the effect of exogenous SA on the arbutin content of pear using HPLC and investigate the mechanism for arbutin accumulation using RNA-Seq analysis. HPLC revealed that SA increased the arbutin contents of leaf, fruit, and callus in pear and demonstrated that the effect of SA is concentration and time dependent. RNA-Seq analysis of pear callus treated with or without SA revealed 380 differentially expressed genes (DEGs), 335 of which were up-regulated. According to a KEGG database analysis, the highest number of genes were annotated for phenylpropane biosynthesis. Overall, 21 DEGs were found to be involved in the synthesis of hydroquinone and UDP-glucose, which are substrates of arbutin synthesis. It is noteworthy that the expression levels of three up-regulated genes (Pbr006844.1, Pbr021064.1 and Pbr021069.1) related to hydroquinone glycosyltransferase were induced by SA and hydroquinone. Furthermore, transient overexpression of PbUGT72B1 (Pbr021069.1) increased the arbutin content in pear callus. These data explain the regulation of gene transcription associated with the promotive effect of SA on arbutin biosynthesis in pear, thus providing a theoretical foundation for enhancing the arbutin content of fruit through genetic engineering.

The membrane proteins of the magnesium transporter (MGT) family are essential to Mg homeostasis. However, there has not been a comprehensive study of MGT in pear. The 17 MGT that were renamed to PbMGT1–17 in this study were found in the pear genome database. Phylogenetically, PbMGT proteins were categorized into three groups, namely NIPA, MRS2, and CorA. The majority of PbMGT were hydrophobic proteins situated on the chloroplast, according to the characterization study. Members of the same group shared comparable conserved motifs and gene structure, as revealed by motif and exon/intron analysis. The application of gene ontology (GO) and cis-elements has demonstrated that PbMGT genes exhibit a high degree of sensitivity to stressors and take part in chloroplast development and Mg⁺ ion transport. It was discovered by tissue-specific expression analysis that PbMGT genes might have a role in the development of organs. The critical significance of PbMGT was shown through comprehensive expression in five pear cultivars at various fruit developmental stages. The PbMGT5 gene was significantly expressed throughout fruit development, suggesting a role in the setting and ripening processes of pear fruits. For the first time, our research brought attention to the function of PbMGT genes as they relate to fruit development. Our research is likely to serve as an incentive for the development of pear breeding initiatives in the future.