During development and maturation of oranges and mandarins it has been also suggested that the l-galactose and d-galacturonic acid pathways are predominant contributors to the AsA pool [9,27]. Expression of GalUR12 paralleled AsA increment in Satsuma mandarin through ripening (Fig. 5C) and it has been described that GalUR12 transcripts are accumulated at higher levels in orange than in Satsuma mandarin, thus contributing to the differences in AsA content observed between these two species [9]. Moreover, GalUR12 followed by GalUR8 were the most abundant isoforms found in Citrus fruit [9] and GalUR12 is more highly expressed in fruit than in other tissues [27].