Expression profiling of redox-metabolism-related genes and proteins during sweet pepper ( Capsicum annuum L.) fruit ripening

Pepper ( Capsicum annuum , L.) fruit ripening is characterized by important phenotypic and metabolic changes, with emission of volatile compounds, cell wall softening, chlorophyll degradation, and new pigments and proteins’ synthesis. Recent data have shown that reactive oxygen and nitrogen species (ROS/RNS) are involved in fruit ripening by regulating both gene expression and protein functions through post-translational modifications. In this work, using immature (green) and ripe (red) pepper fruits, RNA-sequencing was performed through an Illumina platform. Raw reads were pre-processed and assembled resulting in a representative transcriptome of 63,353 tentative transcripts (TTs), of which 29,716 had a unique orthologue. Differential expression analysis between green and red pepper fruits showed that 4,325 and 3,269 transcripts were down-and up-regulated respectively at ripening. Moreover, isobaric tags for relative and absolute quantification (iTRAQ®) was used as a proteomic approach, identifying 2,574 proteins, of which 1,189 showed differential expression. In this study, we have combined transcriptomic and proteomic data focusing on oxidative metabolism and antioxidative systems to gain insight into their role on fruit ripening.