The origin of floral identity quartets

Where do flowers come from? Their sudden appearance and rapid radiation was described as an “abominable mystery” by Charles Darwin. Ruelens et al. examine the genetic toolkit that underpins reproductive organ formation in gymnosperms to uncover the origins of flowers (which they pragmatically describe as “an assembly of protective, attractive and reproductive male and female leaf-like organs”). The authors compare the four-protein complexes (floral identity quartets) that bind to and regulate genes that produce reproductive organs in angiosperms and gymnosperms. From protein phylogenies, the authors identify and reconstruct putative, ancestral forms of these DNA-binding proteins, and examine their interactions in vitro and in yeast cells. Their study finds that the angiosperm floral quartets arose by gene duplication just before the origin of flowering plants, and that the subsequent protein interaction changes were the result of gradual and reversible evolutionary change. Plant Cell 10.1105/tpc.16.00366