Aroma in food plays an important role in food perception and acceptance, which depends on various mixtures of volatile organic compounds (VOCs). Moreover, VOCs are of great significance for aroma identification. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC-MS) technology was used to determine the VOCs in 10 pear syrups. A total of 127 VOCs were quantitatively determined, including 9 common VOCs and 46 characteristic VOCs of 10 pear syrups. The pear syrups were divided into three categories by cluster analysis, and thirty-eight differential VOCs were obtained using orthogonal partial least squares discrimination analysis (OPLS-DA) and fourteen key VOCs were selected by odor activity value (OAV). It was revealed that the key and common aroma components of pear syrups were butanoic acid, methyl ester, 2-methyl-, methyl ester and Hexanoic acid, and ethyl ester. The characteristic and differential VOCs were 10-Undecen-1-ol, Hexadecanal, n-Propylacetate, Cyclohexanol, 5-methyl-2-(1-methylethyl)-, (1S,2R,5S)-, Methional, Disulfide, dimethyl, 8-Nonenoic acid, ethyl ester, Naphthalene, 1,2-dihydro-1,1,6-trimethyl-, 3H-Purin-6-amine, N,N,3-trimethyl-, 2-Octanol,2,6-dimethyl-, Furyl hydroxymethyl ketone, Heptane, 2,2,4,6,6-pentamethyl-, and Butanoic acid,2-methyl-,methyl ester. The above results showed that different pear syrups had rich diversity in aroma compounds, with some components being shared among them while others are exclusive to specific syrups.

Sweet cherry (Prunus avium L.) is becoming increasingly popular in China, but its postharvest quality deteriorates significantly during harvest storage and transport. Here, we investigated the efficiency of different modified atmosphere packaging (MAP) treatments on the quality and physiology of ‘Meizao’ sweet cherry during 60 days of cold storage (0 ± 0.5 °C). Fruits were sealed in four types of MAP low-density polyethylene (LDPE) liners (PE20, PE30, PE40, and PE50), with unsealed 20 μm LDPE packaging bags used as the control. Our findings demonstrated that PE30 packaging established an optimal gas composition (7.0~7.7% O₂ and 3.6~3.9% CO₂) that effectively preserved ‘Meizao’ sweet cherry quality. It maintained the fruit color, firmness, soluble solid content (SSC), titratable acidity (TA), and vitamin C (Vc) content while simultaneously delaying deteriorative processes such as weight loss, pedicel browning, and fruit decay. These results indicate that PE30 was the most suitable treatment for preserving the quality of ‘Meizao’ sweet cherries during cold storage. Furthermore, physiological research showed that significant inhibition of respiration rate was achieved by PE30, accompanied by maintained activities of antioxidant enzymes (CAT, POD, and SOD), which consequently led to reduced accumulations of ethanol and malondialdehyde (MDA) during cold storage. To date, no systematic studies have investigated the physiological and biochemical responses of ‘Meizao’ to different thickness-dependent LDPE-MAP conditions. These observations highlight the power of the optimized PE30 packaging as an effective method for extending the fruit storage life, delaying postharvest senescence, and maintaining fruit quality of ‘Meizao’ sweet cherry.

The study aimed to investigate the effects of thifluzamide (2.67 mg/L) on ‘Huangguan’ pear fruit rot caused by Rhizoctonia solani during storage, as well as the activities of polygalacturonase (PG), pectin methylesterase (PME), polygalacturonic acid trans-eliminase (PGTE), pectin methyl trans-eliminase (PMTE), xylanase, and pectate lyase (PL) secreted by R. solani. The results showed that thifluzamide treatment significantly inhibited the activities of PG, PME, PGTE, PMTE, xylanase, and PL secreted by R. solani after 3 days in vitro culture, compared to the control. Thifluzamide also increased the activities of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), and 4-coumarate CoA ligase (4CL), and the contents of flavonoids and total phenolic compounds in pear fruit. Furthermore, thifluzamide increased the expression of PcPAL, PcC4H, Pc4CL, Pcβ-1,3-GA, PcLCH, PcF3H, and PcDFR involved in phenylpropanoid metabolism in pear fruit. In conclusion, thifluzamide treatment reduced the infection ability of R. solani by inhibiting the expression of the genes encoding cell wall-degrading enzymes in R. solani. At the same time, it inhibited the activities of cell wall-degrading enzymes induced resistance against R. solani infection in ‘Huangguan’ pears by promoting phenylpropane metabolism.

Laccase (LAC), a copper-containing polyphenol oxidase, is an important pathogenic factor of pathogenic fungi, and has been identified as an important virulence factor in numerous pathogenic fungi. LAC is encoded by a gene family and belongs to the class of multicopper oxidases. The study aimed to identify the LAC genes in Athelia bombacina (Link) Pers, and their interactions with the host. The expression levels of the LAC genes were quantified using RT-qPCR. The LAC activity, level of malondialdehyde (MDA) and activities of protective enzymes in ‘Huangguan’ pears during the interaction were measured. The AbLac4 gene deletion mutant strain was constructed. Six LAC genes were identified in A. bombacina, distributed across three chromosomes. Interspecies collinearity analysis suggested that LAC genes could serve as crucial pathogenic factors in A. bombacina. The LAC gene family can be classified into three distinct subgroups. Among the subgroups, variations were observed in their characteristic sequences and conserved motifs. However, the LAC genes within the same subgroup exhibited a high degree of conservation. The genes showed diverse expression profiles, with their promoters harboring multiple stress-responsive elements. Signal peptide prediction showed that all LAC proteins, with the exception of the AbLac3 protein, possessed signal peptides, indicating that they are secretory proteins. The subcellular localization analysis showed that all LAC proteins may be localized extracellularly. RT-qPCR revealed differential expression patterns among LAC genes; specifically, AbLac1 and AbLac4 exhibited distinct expression dynamics during the infection process. The LAC activity first increased and then decreased, with the highest increase rate occurring in the early stage of culture. The MDA content and catalase (CAT) activity at the inoculated site were found to be significantly higher than the uninoculated control. In addition, the deletion of AbLac4 gene reduced the growth rate and pathogenic ability of A. bombacina. This investigation found that AbLac1 and AbLac4 may play pivotal roles in mediating host interactions, and the fruit may combat pathogen infection through increasing the activities of CAT, phenylalanine ammonia lyase and peroxidase. This study provides valuable new insights into the pathogenic mechanisms of A. bombacina, significantly contributing to the field.