The hard way to produce red

Plant Science The common garden petunia delivers flowers in a variety of colors and color patterns, which are pollinated by bees, hawkmoths, or hummingbirds (which are particularly fond of the color red). Throughout evolution, petunia lineages have gained, lost, and shifted color. For example, Petunia exserta has evolved a red hue new to the genus. Barardi et al. investigated how P. exserta acquired color from a colorless ancestor. The authors found that disabling mutations in a transcription factor freed up substrate for anthocyanin biosynthesis, and another transcriptional activator promoted anthocyanin biosynthesis after it shifted expression domains. The red color depends on delphinidins, which tend to be blue or purple, but when dihydroxylated in P. exserta , these pigments contribute to the red hue. In addition, lack of acylation on the anthocyanidin backbone also helps to shift the pigment toward red. Plant Cell 10.1093/plcell/koab114 (2021).