Pear is a kind of common temperate fruit, whose metabolite composition that contributes to the difference in fruit quality is unclear. This study identified and quantified the metabolites using a widely targeted LC-MS/MS approach in three pear species, including Pyrus bretschneideri (PB), Pyrus usssuriensis (PU) and Pyrus pyrifolia (PP). A total of 493 metabolites were identified, consisting of 68 carbohydrates, 47 organic acids, 50 polyphenols, 21 amino acids, 20 vitamins, etc. The results of PCA and OPLS-DA demonstrated that the metabolite compositions differed distinctly with cultivar variability. Our results also involved some metabolic pathways that may link to the fruit quality based on KEGG pathway analysis, the pathway of phenylalanine metabolism revealed significant differences between PB and PP (p < 0.05). Furthermore, the study selected D-xylose, formononetin, procyanidin A1 and β-nicotinamide mononucleotide as the major differentially expressed metabolites in the three species. The present study can open new avenues for explaining the differences in fruit quality of the major commercial pear cultivars in China.

Cold plasma (CP) is a green and efficient preservation technology, but its effect on preventing the postharvest softening of fruits and vegetables is still unclear, and the effects of different CP intensities on the postharvest softening of winter jujubes (Ziziphus jujuba Mill. cv. Dongzao) have been little studied. In this study, we investigated the effects of different CP intensities (0 kV, 40 kV, and 80 kV) on the postharvest storage quality of winter jujubes and the activities of key enzymes related to softening during storage. The results showed that compared with the control group, the contents of firmness, total soluble solids (TSS), titratable acidity (TA), and vitamin C (VC) in the CP treatment group were higher and the respiratory intensity and weight loss rate were lower. In addition, CP treatment can also inhibit the degradation of protopectin and cellulose and the accumulation of soluble pectin. Moreover, CP treatment inhibited the activities of polygalacturonase (PG), pectin methyl esterase (PME), 3α-L-arabinoside (α-L-Af), 4β-galactosidase (β-gal), cellulase (Cx), and β-glucosidase (β-Glu). This shows that CP treatment has a positive effect on the preservation of winter jujubes, and the preservation effect of the 80 kV treatment was better than that of the 40 kV treatment. This provides a certain basis for cold plasma treatment in the preservation of winter jujubes.

In this study, the physiological indicators, reactive oxygen species (ROS) levels, and activities and expressions of key enzymes related to ROS metabolism were monitored to explore the mechanism of ozone treatment on the shelf life of postharvest Korla fragrant pears. The results show that postharvest fragrant pears treated with ozone had a higher firmness and lower weight loss rate and decay rate during their shelf life, especially in the late stage. Ozone treatment could also delay the occurrence of the respiratory peak and reduce the peak value. The generation rate of superoxide anion (O₂⁻), the hydrogen peroxide (H₂O₂) content, and the malondialdehyde (MDA) level were reduced in the ozone-treated group, while the activities of key enzymes, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), related to ROS metabolism in postharvest fragrant pears were stimulated by ozone treatment, especially in the middle and late stages of shelf life. Analysis of the proteomics results indicates that the POD family enzymes were the main target protein in postharvest fragrant pears treated by ozone during the middle and late stages of shelf life. The activity and expression of antioxidant-related enzymes in postharvest fragrant pears were stimulated by ozone to accelerate the metabolism of ROS and maintain high quality, especially in the middle and late shelf lives.

Crude oil pollution of soil is an important issue that has serious effects on both the environment and human health. Phytoremediation is a promising approach to cleaning up oil-contaminated soil. In order to facilitate phytoremediation effects for oil-contaminated soil, this study set up a pot experiment to explore the co-application potentiality of Tagetes erecta L. with two other methods: microbial agent and biochar. Results showed that the greatest total petroleum hydrocarbon (TPH) biodegradation (76.60%) occurred in the soil treated with T. erecta, a microbial agent, and biochar; the highest biomass and root activity also occurred in this treatment.GC-MS analysis showed that petroleum hydrocarbon components in the range from C₁₀ to C₄₀ all reduced in different treatments, and intermediate-chain alkanes were preferred by our bioremediation methods. Compared with the treatments with biochar, the chlorophyll fluorescence parameter NPQ_Lss and plant antioxidant enzyme activities significantly decreased in the treatments applied with the microbial agent, while soil enzyme activities, especially oxidoreductase activities, significantly increased. Although the correlation between biochar and most plant growth and soil enzyme activity indicators was not significant in this study, the interaction effect analysis found a synergistic effect between microbial agents and biochar. Overall, this study suggests the co-addition of microbial agents and biochar as an excellent method to improve the phytoremediation effects of oil-contaminated soil and enhances our understanding of the inner mechanism.

Moderate ozone exposure has emerged as a sustainable strategy to enhance postharvest quality in perishable fruits. This study investigated the effects of ozone treatment (2.14–19.27 mg/m³) on flat jujube during 70-day cold storage (0 °C). Results demonstrated that following 70 days of storage, the ideal ozone concentration (10.72 mg/m³, T2) led to a decrease in weight loss of 44.8% and preserved 66.7% firmness when compared to the control check (CK) group. The T2 group suppressed the respiration rate and delayed declines in total soluble solids (TSSs) and titratable acid (TA). Mechanistically, ozone enhances enzymatic activity, with T2 elevating superoxide dismutase (SOD), catalase (CAT), and peroxiredoxin (POD) activities while reducing the accumulation of reactive oxygen species (ROS) and lipid peroxidation. Total phenolics and flavonoids in T2 remained 42% and 52% higher than CK at 56 days, correlating with elevated 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) scavenging activities. Browning inhibition (25% lower than the CK group) is linked to suppressed polyphenol oxidase (PPO) activity and phenolic oxidation. Principal component analysis (PCA) confirmed ozone’s efficacy in delaying senescence via ROS homeostasis and antioxidant synergy. These findings establish moderate ozone as a novel, eco-friendly intervention to extend jujubes’ shelf life, emphasizing its dual role in quality preservation and oxidative stress regulation.

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) catalyzes the deamination of phenylalanine, which is the initial step in the biosynthesis of phenylpropanoids. It serves as a crucial enzyme that facilitates the transfer of carbon from primary to secondary metabolism in plants. Duckweed is regarded as a promising chassis plant in synthetic biology research and application, due to its being rich in secondary metabolites and other advantages. The genes encoding PAL in Spirodela polyrhiza (L.) Schleid, the giant duckweed, were investigated in this study. Three SpPAL genes (SpPAL1–SpPAL3) were identified and cloned. All of them were successfully expressed in E. coli, and their recombinant proteins all showed PAL activity. In addition, SpPAL1 and SpPAL2 proteins could also utilize tyrosine as substrate, although the activity was low. A qRT-PCR analysis demonstrated that the expression of SpPAL3 was most pronounced in young fronds. It was found that the expression of SpPAL1 and SpPAL3 was significantly induced by MeJA treatment. Overexpression of SpPAL3 in Lemna turionifera inhibited the growth of fronds and adventitious roots in the transgenic plants, indicating the importance of SpPAL3 in duckweed besides its involvement in the secondary metabolism.