Carbon Dioxide Pretreatment and Cold Storage Synergistically Delay Tomato Ripening through Transcriptional Change in Ethylene-Related Genes and Respiration-Related Metabolism.

Seung-Hun Chae,Kang-Mo Ku,Me-Hea Park,Yoon-Pyo Hong,Jung-Soo Lee,Sun-Ju Kim

doi:10.3390/foods10040744

Abstract

The effects of CO2 pretreatment before cold storage on tomato quality were investigated using physicochemical and transcriptome changes. Harvested tomatoes were treated with 30% or 60% CO2 for 3 h before storage at 4 °C for 14 d (cold storage), followed by transfer to 20 °C for 8 d (ambient conditions). The CO2-treated fruits were firmer with a better appearance than untreated fruits, even after being transferred from 4 °C storage to 20 °C for 8 d. CO2 pretreatment coupled with cold storage synergistically delayed tomato ripening by reducing respiration and lowering lycopene production. The tomatoes treated with 30% and 60% CO2 had fewer pits than untreated fruits after cold storage, even after being transferred to ambient conditions. Moreover, the 60% CO2 treatment significantly suppressed the decay rate. Transcriptome and metabolome functional enrichment analyses commonly showed the involvement of CO2-responsive genes or metabolites in sucrose and starch metabolism, as well as biosynthesis of secondary metabolites—in particular, glycolysis reduction. The most frequently detected domain was the ethylene-responsive factor. These results indicate that altered ethylene biosynthesis and ethylene signaling, via ethylene-responsive transcription factors and respiration-related pathways, appear to control CO2-induced fruit quality.

Highlights

Ethylene production was higher in the CO2-treated fruits than in Respiration rates were higher in tomatoes treated with 30% and 60% CO2 than in the untreated fruits (Figure 1B, inner box)
This difference decreased on the secthe control fruits, indicating the successful absorption of CO2 in the pretreated tomatoes ond day of cold storage, and no significant difference was found among the control, 30%
Rugkong et al [31] reported that uneven ripening in cold-stored tomatoes was related to the downregulation of genes associated with ethylene biosynthesis and signaling, which was reflected in the reduced ethylene production and lycopene accumulation observed in the experiment

Summary

Introduction

Tomatoes have a relatively short postharvest shelf life owing to their rapid ripening rate and sensitivity to cold-storage conditions, which limit their transportability and marketability. Cold storage can maintain vegetable freshness for long periods by suppressing respiration, but it induces a physiological disorder known as chilling injury (CI), which occurs when fruits are held at a critical temperature for too long [1]. These CI symptoms appear when the fruits are subjected to ripening temperatures (20–22 ◦ C) after cold storage (2–6 ◦ C) for more than 2 weeks [3]. CI symptoms usually become pronounced under market-shelf conditions following cold storage, reducing consumer desirability [4]. Practical and feasible techniques to extend the shelf life of tomatoes by reducing postharvest losses and CI are required

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