Analysis of AsA concentration revealed that fruit shading did not affect the content in the pulp, but significantly reduced AsA concentrations in the flavedo in the four Citrus genotypes analyzed (Figs. 2 and 5). Consequently, a complete characterization of the expression levels of AsA-related genes was carried out in flavedo samples, since this tissue was clearly affected by light expo- sure. Similarly, it has been also shown that light activates AsA metabolism solely in the peel of apple fruits, whereas almost no changes were detected in the flesh [31].