Tomato (Solanum lycopersicum) ripening is regulated co-operatively by the action of ethylene and a hierarchy of transcription factors, including RIPENING INHIBITOR (RIN) and NON-RIPENING (NOR). Mutations in these two genes have been adopted commercially to delay ripening, and accompanying textural deterioration, as a means to prolong shelf life. However, these mutations also affect desirable traits associated with color and nutritional value, although the extent of this trade-off has not been assessed in detail. Here, we evaluated changes in tomato fruit pericarp primary metabolite and carotenoid pigment profiles, as well as the dynamics of specific associated transcripts, in the rin and nor mutants during late development and postharvest storage, as well of those of the partially ripening delayed fruit ripening (dfd) tomato genotype. These profiles were compared with those of the wild type tomato cultivars Ailsa Craig (AC) and M82. We also evaluated the metabolic composition of M82 fruit ripened on- or off-the-vine over a similar period. In general, the dfd
mutation resulted in prolonged firmness and maintenance of quality traits without compromising key metabolites (sucrose, glucose/fructose, and glucose) and sectors of intermediary metabolism, including tri-carboxylic acid cycle intermediates. Our analysis also provided insights into the regulation of carotenoid formation and highlighted the importance of the polyamine, putrescine, in extending fruit shelf life. Finally, the metabolic composition analysis of M82 fruit ripened on- or off-the-vine provided insights into the import into fruit of compounds, such as sucrose, during ripening.
Click here for the full report by Dr. Sonia Osorio and Dr. Jocelyn K. C. Rose.