An integrated quality, physiological and transcriptomic analysis reveals mechanisms of kiwifruit response to postharvest transport vibrational stress.

The 'Xuxiang' kiwifruit, a leading cultivar in China known for its high quality and yield, experiences quality degradation due to vibration stress during postharvest transportation. This study simulated the postharvest transportation vibrations of 'Xuxiang' kiwifruits to investigate the effects on the fruit quality and physiology. Different vibration intensities (0.26, 0.79, and 1.5 m s) and durations (0, 24, 48, 72, and 96 h) were applied to analyze the quality, physiological and transcriptomic changes of fruits after vibration stress, as well as the association between quality deterioration, gene networks, and key genes. Results indicated that vibration stress significantly accelerated the deterioration of fruit quality and induced physiological changes. As vibration intensity and duration increased, there was a rapid decrease in fruit firmness and an increase in weight loss, soluble solid content, relative conductivity, ethylene production, respiratory rate, and malondialdehyde levels. The most severe deterioration in fruit quality occurred at a vibration intensity of 1.5 m s. Transcriptome sequencing analysis was conducted on samples from different durations of exposure to the 1.5 m s vibration intensity. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses identified key genes associated with ethylene metabolism and softening. Weighted Gene Co-Expression Network Analysis (WGCNA) and correlation analysis further determined that 24 of these genes were regulated by vibrational stress, impacting ethylene metabolism and cell wall degradation. Vibration stress induced changes in genes related to ethylene metabolism and cell wall degradation, promoting lipid peroxidation and respiratory changes, which compromise cell membrane integrity and lead to quality deterioration. Compared with untreated fruits, vibration stress caused the quality deterioration, physiological changes and transcriptional regulation of kiwifruits, indicating that kiwifruits respond to vibration stress through multiple aspects. It proposes a fresh outlook on the understanding of the mechanism of transport vibration stress and further illustrates the importance of monitoring vibration intensity and duration as well as reducing vibration.