The growth and development of apricot flower organs are severely impacted by spring frosts. To better understand this process, apricot flowers were exposed to temperatures ranging from 0 °C to −8 °C, including a control at 18 °C, in artificial incubators to mimic diverse low-temperature environments. We aimed to examine their physiological reactions to cold stress, with an emphasis on changes in phenotype, membrane stability, osmotic substance levels, and antioxidant enzyme performance. Results reveal that cold stress induces significant browning and cellular damage, with a sharp increase in browning rate and membrane permeability below −5 °C. Soluble sugars and proteins initially rise as osmoprotectants, but their content decreases at lower temperatures. Proline content consistently increases, suggesting a protective role. Antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), exhibit a complex pattern, with initial increases followed by declines at more severe cold conditions. Correlation and principal component analyses highlight the interplay between these responses, indicating a multifaceted adaptation strategy. The findings contribute to the understanding of apricot cold tolerance and inform breeding efforts for improved crop resilience.

Reactive oxygen species (ROS) and salicylic acid (SA) are essential signaling molecules in plant cells that participate in responses to biotic and abiotic stresses. Changes in ROS and SA signals during interactions between pear and the pear scab pathogen Venturia nashicola remain unclear. Herein, we analyzed the roles of ROS in the signal transduction pathway of pear scab resistance using the highly resistant Huangguan and susceptible Xuehua cultivars of pear (Pyrus bretschneideri Rehd). Protoplasts, calluses, and leaves were obtained from 14-year-old pear trees and treated with V. nashicola for different periods. The results showed that ROS rapidly accumulated in protoplasts of both cultivars within a 120-min treatment period, but the fluorescence intensity of ROS differed between cultivars. The H₂O₂ content in fruit-derived calluses of Huangguan peaked at 48 h post-infection at levels 1.85 times higher than those in Xuehua. Induction of H₂O₂ by V. nashicola in Huangguan was more intense than in Xuehua over a 96-h treatment period. At 96 h post-infection, the malondialdehyde content in leaves of Huangguan was significantly lower than in Xuehua, while the activities of superoxide dismutase, peroxidase, and catalase, and the relative expression levels of PbMnSOD, PbPOD, and PbCAT genes were higher in Huangguan than Xuehua. V. nashicola infection also caused a continuous increase in the leaf SA content of Huangguan, which was 6.76 times higher than in Xuehua at 96 h post-infection, and V. nashicola exposure upregulated the expression of PbPAL, PbICS, PbPR1, and PbPR5. In summary, both ROS and SA participated in the responses of pear trees to V. nashicola infection and played vital roles in the signal transduction pathway of pear scab resistance.

Fruit hardening, one of the physiological disorders influencing the quality of pear, is usually accompanied by fruit lignification. Nonetheless, the mechanism by which lignin accumulates in hardened pear fruit is still unknown. Here, Transcriptome analysis of normal fruits (NFs) and hardened fruits (HFs) of ‘Suli’ pear (Pyrus bretschneideri Rehd) was used to examine the molecular mechanism of fruit hardening. We found that hardened fruits (HFs), especially those in the top region within 35–180 days after flowering (DAF), possessed a prominently higher lignin level than normal fruits (NFs). Subsequently, transcriptome sequencing of fruit at 35 DAF identified 4391 [HF shoulder region (HF_S) vs. NF top region (NF_T)], 3849 (HF_T vs. NF_T) and 408 (HF_T vs. HF_S) differentially expressed genes. Among them, we clarified 26 unigenes that encode 10 enzymes as candidate genes participating in lignin biosynthesis. Thus, high expression of the lignin biosynthetic gene impels lignin to accumulate in HFs. Some transcription factors were evaluated to link with lignin formation and subsequently analysed. In addition, the genes participating in flavonoid/proanthocyanidin biosynthesis dropped from the HF_T to the HF_S, suggesting that the flavonoid metabolic pathway was reduced to promote intermediate metabolites to be converted to the lignin biosynthetic pathway. To conclude, this study lays a solid theoretical foundation and provides reference data for investigating the mechanism by which lignin accumulates in hardened pear fruit.

Despite extensive research highlighting the pivotal role of MYB transcription factors in regulating anthocyanin biosynthesis, the interactive regulatory network involving these MYB factors in pear fruits remains inadequately characterized. In this study, the anthocyanin-regulatory gene PbrMYB114 was successfully cloned from ‘Yuluxiang’ pear (Pyrus bretschneideri) fruits, and its influence on anthocyanin accumulation was confirmed through transient expression assays. Specifically, the co-transformation of PbrMYB114 with its partner PbrbHLH3 in pears served to validate the functional role of PbrMYB114. Subsequently, PbrMYB114 was employed as bait in a yeast two-hybrid screening assay, using a ‘Yuluxiang’ pear protein library, which led to the identification of 25 interacting proteins. Further validation of the interactions between PbrMYB114 and PbrMT2/PbrMT3 was conducted. Investigations into the role of PbrMT2 and PbrMT3 in ‘Duli’ seedlings (Pyrus betulaefolia) revealed their potential to enhance anthocyanin accumulation. The outcomes of these studies provide novel insights into the protein network that regulates pear anthocyanin biosynthesis, particularly the functional interactions among PbrMYB114 and associated proteins.

Gaoping Dahuangli is a landrace pear grown for more than four centuries in Gaoping County, Shanxi Province, and a National Geographical Indication (GI) product since 2013. What distinguishes it chemically from other pears—and how that distinction can be proved in the marketplace—has not been established. We profiled the fruit metabolome of Dahuangli and four commercial reference cultivars (Korla xiangli, Jingbaili, Clapp’s Favorite, and Akizuki) by widely targeted UHPLC-MS/MS metabolomics (five varieties × three biological replicates, single harvest season) and measured eight quality attributes. Of 2335 annotated metabolic features, 136 were consistently more abundant in Dahuangli than in every reference variety. Flavonoids (48) and terpenoids (25) made up over half of this set; the single most enriched compound was sophorabioside, an isoflavone, at a minimum fold change of 120.7×. Dahuangli combined the firmest flesh (7.27 kg/cm²) with the lowest sugar/acid ratio (38.6) and the yellowest peel (b* = 51.41). On this basis we propose a candidate two-tier authentication framework: 32 candidate biomarkers enriched more than 10-fold for laboratory confirmation, 104 further metabolites for corroborative pattern matching, and two field-measurable proxies—firmness and the sugar/acid ratio—for low-cost first-stage screening. These exploratory results give a four-century-old landrace its first objective chemical definition and offer regulators, producers, and consumers a candidate toolkit—two field-measurable proxies backed by a 32-compound laboratory panel—for exposing substitution and protecting the Dahuangli geographical indication, pending multi-year and multi-orchard validation.