Ectopic overexpression of ShCBF1 and SlCBF1 in tomato suggests an alternative view of fruit responses to chilling stress postharvest

Postharvest chilling injury (PCI) is a physiological disorder that often impairs tomato fruit ripening; this reduces fruit quality and shelf-life, and even accelerates spoilage at low temperatures. The CBF gene family confers cold tolerance in Arabidopsis thaliana, and constitutive overexpression of CBF in tomato increases vegetative chilling tolerance, in part by retarding growth, but, whether CBF increases PCI tolerance in fruit is unknown. We aimed to induce high levels of CBF1 cloned from S. lycopersicum and S. habrochaites in fruit undergoing postharvest chilling, using the stress-inducible RD29A promoter. We hypothesized that CBF1 overexpression would be induced in the cold and increase resistance to PCI.Wild type and transgenic fruit were harvested and cold-stored (2.5 degrees C) for 6 hours or 1 week. Transcriptomic analysis revealed that the ripening and biotic and abiotic stress responses were altered in the cold-stored transgenic fruit to a greater extent than the wild type samples.