Transcriptomic analysis on the regulation of tomato ripening by carbon dioxide

Authors: BOBOKALONOV, JAMSHED - US Department Of Agriculture (USDA); Liu, Yanhong; Mahalak, Karley; Firrman, Jenni; Sheen, Shiowshuh - Allen; ZHOU, SIYAN - Southwest University; Liu, Linshu

Submitted to: Sci
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2023
Publication Date: 6/30/2023
Citation: Bobokalonov, J., Liu, Y., Mahalak, K.K., Firrman, J., Sheen, S., Zhou, S., Liu, L.S. 2023. Transcriptomic analysis on the regulation of tomato ripening by carbon dioxide. Sci. 5(3):26. https://doi.org/10.3390/sci5030026.
DOI: https://doi.org/10.3390/sci5030026

Interpretive Summary: Carbon dioxide, among several other reagents, is used to delay the ripening of tomatoes to preserve the quality of tomatoes during refrigeration or packaging. However, the dose and duration of the CO2 treatment, and the mechanism by which CO2 delays ripening, remained unclear. In this study, the color change and firmness of three groups of tomatoes, treated with either 5% CO2 for 14 d (T1), 100% CO2 for 3 hr (T2), and those without treatment (CT), were followed during ripening. The shelf life of tomatoes decreased in the sequence of T1 > T2 > CT. Furthermore, in contrast to T1, T2 promoted ethylene production, indicating that T1 and T2 regulate tomato ripening via different mechanisms. These results form the base for development of new technologies for fruit preservation using CO2. The research also provides new insights on CO2 stress on tomato metabolism at the genetic level.

Technical Abstract: Tomatoes are a perishable and seasonal fruit with high economic impact. Carbon dioxide, among several other reagents, is used to extend the shelf life and preserve the quality of tomatoes during refrigeration or packaging. To obtain insight on CO2-induced stress during tomato ripening, tomatoes at the late green mature stage were conditioned with one of two CO2 delivery methods, 5% CO2 for 14 days (T1) or 100% CO2 for 3 hr (T2). Conventional physical and chemical characterization found that CO2, delivered by either T1 or T2, delayed tomato ripening in terms of color change, firmness, and carbohydrate dissolution. However, T1 had longer-lasting effects. Furthermore, CO2 suppressed ethylene production by T1, and promoted it by T2. The physical observations were further evaluated by RNA-Seq analysis at the whole genome level, with examination of the genes involved in ethylene synthesis, signal transduction, and carotenoid biosynthesis. Transcriptomics analysis revealed that the introduction of CO2 by T1downregulated genes related to fruit ripening, and by T2 upregulated the gene encoding for ACS6, the enzyme responsible for S1 ethylene synthesis, even though there was a large amount of ethylene present. Quantitative real-time PCR assays (qRT-PCR) were used for validation, which substantiated the RNA-Seq data. The results of the present research provide insight on gene regulation by CO2 during tomato ripening at the whole genome level.