ON THE COVER

Land plants synthesize a family of flavonoid metabolites that provide pigmentation in flowers, fruits, and seeds to attract pollinators and seed dispersers. The cover image illustrates the accumulation of anthocyanin, the major flavonoid pigment, in the blooming flowers and developing siliques of Arabidopsis species. Zhang et al. (pages 1157–1174) discovered a crucial proteolytic regulator, a Kelch domain-containing F-box (KFB) protein, in the model plant Arabidopsis, which specifically interacts with chalcone synthase in the flavonoid biosynthetic pathway and mediates its stability in response to the development cues and environmental stimuli, thereby coordinately controlling flavonoid production. This work deepens our mechanistic understanding of the molecular regulation of flavonoid pigment synthesis and provides us with a molecular tool for engineering flavonoid accumulation in plants. Photo by Roger Stoutenburgh.