Molecular Responses of Red Ripe Tomato Fruit to Copper Deficiency Stress.

Fruit nutritional value, plant growth, and yield can be compromised by deficient copper (Cu) bioavailability, which often appears in arable lands. This condition causes low Cu content and modifications in the ripening-associated processes in tomato fruit. This research studies the transcriptomic changes that occur in red ripe tomato fruit grown under suboptimal Cu conditions to shed light on the molecular mechanisms underlying this stress. Comparative RNA-sequencing and functional analyses revealed that Cu deficiency during cultivation activates signals for metal ion transport, cellular redox homeostasis, pyridoxal phosphate binding, and amino acid metabolism while repressing the response to phosphate starvation in harvested fruit. Transcriptomic analyses highlighted a number of novel Cu stress-responsive genes of unknown function and indicated that Cu homeostasis regulation in tomato fruit may involve additional components than those described in model plants. It also studied the regulation of high-affinity Cu transporters and a number of well-known Cu stress-responsive genes during tomato fruit ripening depending on Cu availability, which allowed potential candidates to be targeted for biotechnological improvements in reproductive tissues. We provide the first study characterizing the molecular responses of fruit to Cu deficiency stress for any fruit crop.