Induction of ARI12 upon broad band UV-B radiation is suppressed by UVR8 and cryptochromes

Abstract

ARI12 belongs to a family of 16 potential E3 ligases in Arabidopsis and is strongly induced in leaves upon low and high fluence rates (HFR) of UV-B. We have shown that ARI12 is a downstream target of the UV-B receptor, UVR8, and the transcription factors HY5 and HYH under low fluence rates. However under HFR of broad band UV-B ARI12 expression was still downstream of HY5 and HYH but increased in uvr8 mutants. To determine if other photoreceptors are responsible for the induction of ARI12 we quantified its expression in double mutants of the UV-A and blue light receptors, CRY1/2 and PHOT1/2, and the red light receptors PHYA/B. While the expression of ARI12 was increased in cyr1/2 it was unaffected in phot1/2 and phyA/B. Therefore ARI12 expression is suppressed by UVR8 and cryptochromes, and independent of phototropins and phytochromes A and B upon HFR of broad band UV-B.

Keywords: :

• UV-B
• ARI12
• phytochrome
• cryptochrome
• phototropin
• UVR8

Disclosure of Potential Conflicts of Interest

There were no potential conflicts of interest to expose.

Acknowledgments

We thank Gareth Jenkins for cry1/2, phot1/2 and phyA/B double mutants, Roman Ulm for uvr8–6 and Christina Lang-Mladek for the pARI12:GUS line. The research was supported by the Austrian Science Fund (FWF) projects (P17888-B14, F3707) to M. -T. H. and the COST-FA0906 action UV4growth. LSX received a China scholarship council (CSC) fellowship.