UV-B Radiation Induces Root Bending Through the Flavonoid-Mediated Auxin Pathway in Arabidopsis

Ultraviolet (UV)-B radiation-induced root bending has been reported, however, the underlying mechanisms largely remain unclear Here, we investigate whether and how auxin and flavonoids are involved in UV-B radiation induced root bending in Arabidopsis using physiological, pharmacological, and genetic approaches UV-B radiation modulated the direction of root growth by decreasing IAA biosynthesis and affecting auxin distribution in the root tips, where reduced auxin accumulation and asymmetric auxin distribution were observed UV-B radiation increased the distribution of auxin on the nonradiated side of the root tips, promoting growth and causing root bending Further analysis indicated that UV-B induced an asymmetric accumulation of flavonoids, this pathway is involved in modulating the accumulation and asymmetric distribution of auxin in root tips and the subsequent redirection of root growth by altering the distribution of auxin carriers in response to UV-B radiation Taken together, our results indicate that UV-B radiation-induced root bending occurred through a flavonoid mediated phototropic response to UV-B radiation.