Carbon Dioxide Pretreatment on Tomatoes Before Cold Storage Synergistically Delays Ripening Through Transcriptional Change of Ethylene-Related Genes and Respiration-Related Metabolisms

The effect of CO2 pre-treatments on tomato quality prior to cold storage was investigated using physiochemical and transcriptome changes. Three hours CO2 treated fruits were firmer than untreated fruits and had a good appearance even after being transferred from 4°C storage to 20°C for 8 d. CO2 pretreatment with cold storage showed a synergistic effect on delayed ripening through reduced respiration; these tomatoes exhibited a lower lycopene content than untreated fruit under cold storage. Tomatoes treated with 30% CO2 had fewer pits than untreated fruits subjected to chilling temperatures, even after being transferred to 20°C for 8 d. Functional enrichment analyses from transcriptome and metabolome commonly showed that CO2-responsive genes or metabolites were involved in the sucrose and starch and biosynthesis of secondary metabolisms. The most frequently detected domain, ethylene-responsive factor domain and reduced glycolysis provide insights into the mechanism that CO2 regulates tomato quality.