Transgenic expression of flavanone 3-hydroxylase redirects flavonoid biosynthesis and alleviates anthracnose susceptibility in sorghum.

: Flavonoids are ubiquitous in terrestrial plants with important physiological functions. The in planta flavonoid profile depends on the activities of different biosynthesis enzymes (Figure 1a). Flavanone 3-hydroxylase (F3H) is a key enzyme channeling carbon flow towards the production of 3-hydroxylated flavonoids, including flavonols and anthocyanidins. In Poaceae, F3H-encoding genes are generally inactive in vegetative tissues which accumulate flavone derivatives as the predominant flavonoid metabolites. Meanwhile, sorghum produces 3-deoxyanthocyanidins and flavones as phytoalexins for defense against pathogens such as Colletotrichum sublineola, the causal agent of anthracnose.