In the flavedo of Navelina oranges the three APX isoforms were clearly up-regulated by light at latter ripening stages under normal photoperiod conditions (December; Fig. 3C). On the other hand, in mandarin, transcription of APX1 and APX4 genes was also enhanced in light-exposed fruits but earlier and at lower extent than in oranges (Fig. 4C). These increases in the expression of the APX isoforms may contribute to the slight reduction in AsA content observed in both genotypes after November (Fig. 2). This is in agreement with the previous observation reporting that APXs are particularly sensitive to inhibition by low ascorbate concentration [54]. Despite APX may be involved in the regulation of the AsA pool during ripening, the pattern of changes of these genes did not correlate with the differences between light and dark-exposed fruit. In apple peel, however, it has been proposed that APX contribute to the regulation of AsA pool by light [31,36], which may reflect a genus-specific effect.