Evolutionary Rewiring of Anthocyanin Biosynthesis Pathway in Poaceae

Poaceae is a species-rich family of plants in the monocots harboring many important crop species. As grasses, these plants lack striking flowers that are typically pigmented by anthocyanins. Here, we investigated the anthocyanin biosynthesis genes in Poaceae and characterized several striking patterns. (1) An independently evolved MYB lineage (ncaMYB) is responsible for the regulation of the anthocyanin biosynthesis in Poaceae. (2) The independently evolved BZ2 lineage replaced the otherwise widespread TT19/An9 lineage as anthocyanin-related glutathione S-transferase in Poaceae. (3) The anthocyanin biosynthesis genes ANS, arGST (BZ2), and the anthocyanin biosynthesis activating MYB (ncaMYB) appear to be absent from the genus Brachypodium. These observations could be explained by a loss of the anthocyanin biosynthesis at the basis of the Poaceae, followed by an evolutionarily independent regain and again a loss of the anthocyanin biosynthesis in Brachypodium.