Flower colour and cytochromes P450

摘要: Flavonoids are major constituents of flower colour. Plants accumulate specific flavonoids and thus every species often exhibits a limited colour range. Three cytochromes P450 play critical roles in the flavonoid biosynthetic pathway. Flavonoid 3′-hydroxylase (F3′H, CYP75B) 3′,5′-hydroxylase (F3′5′H, CYP75A) catalyze hydroxylation B-ring necessary to biosynthesize cyanidin-(red magenta) delphinidin-(violet blue) based anthocyanins, respectively. Pelargonidin-based anthocyanins (orange red) synthesized their absence. Some such as roses, carnations chrysanthemums do not have violet/blue due deficiency F3′5′H. Successful expression heterologous F3′5′H genes roses results delphinidin production, causing novel blue/violet Down-regulation F3′H has yielded orange petunia pink torenia that pelargonidin-based anthocyanins. Flavone synthase II (CYP93B) catalyzes synthesis flavones contribute bluing colour, modulation FNSII gene tobacco changes Extensive engineering anthocyanin pathway is therefore now possible, can be expected enhance range colours.