Phenolic compounds are the predominant chemical constituents in the secondary metabolites of plants and are commonly found in pears. In this study, we focused on the analysis of the phenolic composition and antioxidant activity of leaves from five pear cultivars (Cuiguan, Chaohong, Kuerle, Nanguoli, and Yali) and tea leaves (Fudingdabai as the control) using ultra-performance liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry. The results indicated significant differences in the amount and composition of phenolic metabolites between tea and pear leaves, as well as among the five pear varieties. Only approximately one-third of the metabolites exhibited higher levels in pear leaves compared to that in tea leaves. The total phenol content in the Yali cultivar was higher than that in the other pear cultivars. Furthermore, specific phenolic metabolites with high expression were identified in the leaves of different groups. The levels of delphinidin 3-glucoside, aesculin, prunin, cosmosiin, quercetin 3-galactoside, isorhamnetin-3-O-glucoside, nicotiflorin, narcissin, chlorogenic acid, and cryptochlorogenic acid were relatively high among the five pear cultivars. (-)-Gallocatechin gallate, 6-methylcoumarin, aesculetin, hesperidin, kaempferol, and caftaric acid were identified as specific metabolic substances unique to each type of pear leaf. Most of the differential metabolites showed positive correlations and were primarily enriched in the flavonoid biosynthesis, flavone and flavonol biosynthesis, and phenylpropanoid biosynthesis pathways. DPPH (1,1-Diphenyl-2-picrylhydrazyl radical) analysis indicated that the Yali cultivar exhibited the highest antioxidant activity compared to other varieties. This systematic analysis of the differences in phenolic metabolite composition and antioxidant activity between pear and tea leaves provides a theoretical foundation for the development and utilization of pear leaf resources.

The “Qixiadaxiangshui” pear (Pyrus bretschneideri Rehd.1) is a highly valued cultivar known for its crisp texture, abundant juice, and rich aroma. In this study, we reported the first complete chloroplast genome sequence of the “Qixiadaxiangshui” pear, which is 159,885 bp in length with a GC content of 36.58%. The genome exhibits a typical circular quadripartite structure, comprising a large single-copy region (LSC), a small single-copy region (SSC), and a pair of inverted repeat regions (IRs). A total of 131 genes were identified, including 84 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. We also identified 209 simple sequence repeats (SSRs) and several mutation hotspots, such as ndhC-trnM-CAU and trnR-UCU-atpA, which can be applied in molecular identification and phylogenetic studies of Pyrus. Comparative genomic analysis showed high conservation among ten pear cultivars. Phylogenetic analysis indicated that the “Qixiadaxiangshui” pear is closely related to germplasm Dangshansuli, Wonwhang, and Yali, suggesting a recent common ancestor. These findings provided valuable insights into the genetic diversity and evolutionary dynamics of the Pyrus species and contribute to the conservation and breeding of pear germplasm resources.

Fruit shape is an important quality and yield trait of pear, and the fruit shape of ‘Laiyang Cili’ presents a spindle shape which seriously affects its commercial value. Calyx excision treatment could change the fruit shape, while the underlying genes and their regulatory mechanism remain poorly understood. In this study, we constructed RNA-seq libraries of pear treated with calyx excision to explore underlying regulatory mechanisms. At the early stage of the calyx excision treatment, the numbers of differentially expressed genes (DEGs) between each comparison group were relatively high and gradually decreased along with fruit development. The expression pattern of the DEGs ranked in the top 30 of the six groups had obvious divergence, and DEGs were mainly distributed in the “after calyx excision treatment (0 days)” (AC0d) and AC2d groups. The DEGs were mainly enriched in plant hormone signal transduction and plant defense response. We identified 17 candidate genes related to fruit shape and tested their expression patterns along with fruit development. Among them, nine candidate genes expression trends were consistent with fragments per kilobase of exon model per million mapped fragment (FPKM) values, including MYB62, outer envelope pore protein 62 (OEP62), auxin response factor 3 (ARF3), auxin-responsive protein 50 (SAUR50), protein phosphatase 2C 51 (PP2C 51), major allergen Pyr c 1 (PYRC1), aquaporin TIP1-3 (TIP1-3), transcription factor TGA4 (TGA4) and auxin-responsive protein 17 (IAA17). And then, weighted gene co-expression network analysis (WGCNA) analysis revealed that the OVATE family protein (OFP) and SUN domain-containing protein (SUN) were divided into the MEblue model, which had a positive correlation with calyx excision treatment, and the expression trend of LOC103960706 (OFP8) appeared cohesive with FPKM values. Pbr014104.1 and Pbr016952.1, which were the ortholog genes of LOC103960706, were further identified from the pear genome, and were found to be highly expressed in pear fruit through RT-PCR analysis. Taken together, the key stage determining the development of fruit shape was in the early stage after calyx excision treatment, and fruit shape regulation and development were co-regulated by multiple genes.