Transcriptomic analysis reveals ozone treatment delays kiwifruit postharvest softening by modulating cell wall metabolism

Kiwifruit ripening and senescence after harvesting are closely related to its economic value. Transcriptome analysis and biochemical parameters were used to investigate the differences in gene expression levels and the potential regulation of cell wall metabolism in kiwifruit treated with ozone, thereby regulating fruit softening and prolonging postharvest life. Compared to the control group, the activities of the cell wall modification enzyme were lower under ozone treatment, the content of polysaccharide in the cell wall of primary pectin and cellulose was higher, and the content of soluble pectin was lower. Meanwhile, ozone treatment delayed the degradation of the cell wall mesosphere during storage. A total of 20 pectinesterase (PE)-related genes were identified by sequencing analysis. The data analysis and quantitative polymerase chain reaction results confirmed that cell wall modifying enzyme genes played an important role in softening and senescence after harvesting, which may reduce or induce the expression of certain genes affecting cell wall metabolism. Ozone treatment not only regulates active genes such as xyloglucan endo glycosyltransferase/hydrolase, cellulose synthase, polygalacturonase, and PE to maintain the quality of fruit after harvest but also acts synergically with cell wall modifying enzymes to inhibit the degradation of cell wall, resulting in changes in the ultrastructure of cell wall, thereby reducing the hardness of kiwifruit. In addition, according to the results of cis-acting elements, cell wall degradation is also related to downstream hormone signaling, especially PE-related genes. These results provide a theoretical basis for studying the mechanism of firmness and cell wall metabolism difference of kiwifruit and also lay a good foundation for further research.

Evolution of pigments and their relationship with skin color and sensory profile in date fruits (Phoenix dactylifera L.)

Abstract Fresh dates of seventeen varieties and khalts from Southern Morocco were analysed for their colour, pigments content, and sensory profile. The results showed significant differences between the sensory profiles of the samples due to the variability of the genotype and their different origin. Fresh date varieties and khalts were a good source of β-carotene (0.49 - 10.86 µg of β-carotene /100 g FW). The results revealed that the date varieties and khalts were found to have an excellent functional composition and good sensory characteristics. Therefore, these varieties of Moroccan dates could be used for fresh consumption and in the processing industry, which will constitute a significant source of antioxidants.

Ozone treatment modulates reactive oxygen species levels in kiwifruit through the antioxidant system: Insights from transcriptomic analysis

Owing to its easy decomposition and residue-free properties, ozone has been used as an effective and environmentally friendly physical preservation method for maintaining the post-harvest quality of fruits. This study aimed to investigate the effects of ozone treatment on the levels of oxidative stress markers and the status of the antioxidant defense system in refrigerated kiwifruit. Additionally, the study aimed to identify the differences in gene expression levels and potential regulatory effects from the transcriptional level. The results showed that ozone treatment reduced the respiration rate, maintained the fruit hardness and storage quality, and inhibited the ripening and senescence of kiwifruit. Ozone treatment activated antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and ascorbate-glutathione cycle to prevent the increase of reactive oxygen species levels (H2O2, O2-•) and malonaldehyde content, maintaining lower membrane lipid peroxidation and reactive oxygen species (ROS) accumulation than the control treatment. Further analysis showed that the regulatory ability of ROS in kiwifruit treated with ozone was not only related to the synergistic effect of enzyme activity and gene expression related to the antioxidant oxidase system and the ascorbate-glutathione (ASA-GSH) cycle but also related to downstream hormone signaling. This study provides a foundation for understanding the potential effects of ozone treatment on the antioxidant cycle of kiwifruit and provides valuable insights into the molecular basis and related key genes involved in regulating ROS to delay aging in kiwifruit.

Edible coating enriched with cinnamon oil reduces the oxidative stress and improves the quality of strawberry fruit stored at room temperature

BACKGROUND

The present study aimed to assess the impact of a starch/gelatine coating containing cinnamon oil on selected quality attributes and redox status in strawberry fruit stored at room temperature (72 h).

RESULTS

Research showed that the application of cinnamon oil to an edible coating allows an improvement of the quality of strawberry fruit stored at room temperature. The cinnamon oil coating inhibits the development of yeast and mould, and reduces loss of soluble solids and ascorbic acid during 72 h storage at room temperature. Moreover, the coating with cinnamon oil clearly reduced the level of oxidative stress, which was manifested by a lower level of reactive oxygen species, as well as a lower activity of antioxidant enzymes. The elimination of oxidative stress in the cinnamon oil-coated fruit also contributed to lower PARP1 mRNA expression, inhibiting the metabolism of NAD⁺ and reducing ATP losses.

CONCLUSION

The coating of strawberry fruit with a starch/gelatine biofilm containing cinnamon oil is an effective method for delaying postharvest senescence of fruit and the storage degradation of tissue. © 2023 Society of Chemical Industry.

One-time ozone treatment improves the postharvest quality and antioxidant activity of Actinidia arguta fruit

The major aim of this study was to check the effect of one-time ozonation on selected quality parameters and antioxidant status of Actinidia arguta fruit. For this purpose, A. arguta fruit was ozonated with gas at a concentration of 10 and 100 ppm, which was carried out successively for 5, 15 and 30 min. Next, the selected quality attributes, antioxidants level as well as NADPH and mitochondrial energy metabolism in mini-kiwi fruit after ozonation were analysed. Our research has shown that ozonation reduced the level of yeast and mould without affecting the content of soluble solids or acidity. In turn, ozonation clearly influenced the antioxidant activity and the redox status of the fruit. The ozonated fruit was characterised by a lower level of ROS due to the higher level of low molecular weight antioxidants, as well as the higher activity of superoxide dismutase and catalase. In addition, improved quality and antioxidant activity of the fruit were indirectly due to improved energy metabolism and NADPH level. The ozonated fruit showed a higher level of ATP, due to both higher activity of succinate dehydrogenase and higher availability of NADH. Moreover, the increased level of NAD⁺ and the activity of NAD⁺ kinase and glucose-6-phosphate dehydrogenase contributed to higher levels of NADPH in the fruit.