Integrated physiological, transcriptomic, and metabolomic analyses reveal the stress response of cucumber seedlings...

Ozonated water, a common disinfectant, effectively controls crop diseases in agriculture. While ozonated water stress causes severe leaf damage in plants, little is known about its effects on cucumber leaves and underlying mechanisms. In this study, we investigated the effects of spraying ozonated water on cucumber seedlings by integrating physiological phenotypes with molecular mechanisms. The results showed that spraying ozonated water led to the disorder of leaf anatomical structure, damage of the photosynthetic system, and the chlorophyll content decreased significantly. Significant changes in oxidative damage indicators, osmotic adjustment substances accumulated, and the antioxidant system were damaged. Transcriptome analysis indicated that spraying ozonated water strongly regulated the expression of stress defense genes. GO and KEGG analyses showed that DEGs were primarily enriched in pathways related to plant antioxidant responses. In addition, in the WGCNA analysis, multiple transcription factors and protein kinases were identified. Metabolomics studies were also conducted, and KEGG enrichment analysis mainly enriched in glutathione metabolism and related amino acid metabolism pathways. Furthermore, comprehensive analysis indicated that spraying ozonated water activated and increased genes and metabolites related to oxidative stress in cucumbers to resist the damage caused by ozonated water stress. Our study systematically revealed how cucumber seedlings adapt to ozonated water stress through physiological and molecular mechanisms, providing a scientific basis for optimizing its agricultural application.