A role for Ethylene-Insensitive 2 gene in the regulation of the ultraviolet-B response in Arabidopsis

The Arabidopsis Ethylene-Insensitive 2 (EIN2) gene was shown to be involved in the regulation of abiotic and biotic stresses, such as ozone stress, high salt, oxidative stress, lead and disease resistances. However, it is unclear whether EIN2 plays a role in mediating the ultraviolet (UV)-B response in Arabidopsis. Here, we show that EIN2 is involved in the regulation of the UV-B response. The EIN2 expression was repressed by UV-B exposure, and ein2-1 mutant plants were more tolerant to UV-B than wild-type plants, as indicated by analysis of survival rates. Significant higher increases in flavonoids and anthocyanins were detected in ein2-1 plants than in wild-type plants treated with or without UV-B treatment, which was associated, at least in part, with constitutively increased transcript levels of two key genes CHALCONE SYNTHASE (CHS) and CINNAMATE 4-HYDROXYLASE (C4H) involved in the biosynthesis pathway of flavonoid and anthocyanins. These results suggest that EIN2 mediates the UV-B response, at least in part, via the modulation of expression of CHS and C4H genes.