Manipulation of ß-carotene levels in tomato fruits results in increased ABA content and extended shelf life

Authors: DIRETTO, GIANFRANCO - Enea Casaccia Research Center; FRUSCIANTE, SARAH - Enea Casaccia Research Center; FABBRI, CLAUDIA - University Of Rome Sapienza; SCHAUER, NICOLAS - Max Planck Institute Of Molecular Plant Physiology; BUSTA, LUCAS - University Of British Columbia; WANG, ZHONGHUA - University Of British Columbia; MATAS, ANTONIO - Cornell University; FIORE, ALESSIA - Enea Casaccia Research Center; ROSE, JOCELYN - Cornell University; FERNIE, ALISDAIR - Max Planck Institute Of Molecular Plant Physiology; JETTER, REINHARDT - University Of British Columbia; MATTEI, BENEDETTA - University Of Rome Sapienza; Giovannoni, James; GOULIANO, GIOVANNI - Enea Casaccia Research Center

Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2019
Publication Date: 12/24/2019
Citation: Diretto, G., Frusciante, S., Fabbri, C., Schauer, N., Busta, L., Wang, Z., Matas, A., Fiore, A., Rose, J., Fernie, A., Jetter, R., Mattei, B., Giovannoni, J.J., Gouliano, G. 2019. Manipulation of ß-carotene levels in tomato fruits results in increased ABA content and extended shelf life. Plant Biotechnology Journal. pp. 1-15. https://doi.org/10.1111/pbi.13283.
DOI: https://doi.org/10.1111/pbi.13283

Interpretive Summary: Plant carotenoids are naturally produced chemicals contributing to the color and nutritional quality of plant derived foods. For example, ß-carotene provides orange coloration to melons, carrots and tomatoes and is converted by the human body to the necessary nutrient, vitamin A. Several prior reports have described the metabolic engineering of plant carotenoid contents. Using two independent tomato transgenic lines, we conducted a system-wide study of the effect of engineering increased ß-carotene levels on tomato fruit ripening and shelf life. Our data suggest that increase in the ß-carotene content influences both nutrient levels and shelf life.

Technical Abstract: Tomato fruit ripening is controlled by the hormone ethylene and by a group of transcription factors, acting upstream of ethylene. During ripening, the linear carotene lycopene accumulates at the expense of cyclic carotenoids. Fruit-specific overexpression of LYCOPENE ß-CYCLASE (LCYb) resulted in increased ß-carotene (provitamin A) content. Unexpectedly, LCYb-overexpressing fruits also exhibited a diverse array of ripening phenotypes, including delayed softening and extended shelf life. These phenotypes were accompanied, at the biochemical level, by an increase in abscisic acid (ABA) content, decreased ethylene production, increased density of cell wall material containing linear pectins with a low degree of methylation, and a thicker cuticle with a higher content of cutin monomers and triterpenoids. The levels of several primary metabolites and phenylpropanoid compounds were also altered in the transgenic fruits, which could be attributed to delayed fruit ripening and/or to ABA. Network correlation analysis and pharmacological experiments with the ABA biosynthesis inhibitor, abamine, indicated that altered ABA levels were a direct effect of the increased ß-carotene content and were in turn responsible for the extended shelf life phenotype. Thus, manipulation of ß-carotene levels results in an improvement not only of the nutritional value of tomato fruits, but also of their shelf life.