Noemi controls production of flavonoid pigments and fruit acidity and Illustrates the domestication routes of modern Citrus varieties
In some varieties of citrus, exceptionally low fruit acidity is associated with absence of anthocyanin pigments in leaves and flowers and proanthocyanidins in seeds. Taking advantage of natural variation, Butelli et al. show that this pleiotropic phenotype is the result of mutations in a single gene, Noemi, encoding a bHLH transcription factor. In citrus, the production of anthocyanin pigments requires the activity of the transcriptional activator Ruby. Consequently, loss-of-function mutations in Ruby result in an anthocyaninless phenotype [1].