Boron-dependent degradation of NIP5;1 mRNA for acclimation to excess boron conditions in arabidopsis

Abstract

Boron (B) is an essential plant micronutrient that is toxic at higher levels. NIP5;1 is a boric acid channel required for B uptake and growth under B deficiency. Accumulation of the NIP5;1 transcript is upregulated under B deficiency in Arabidopsis thaliana roots. To elucidate the mechanism of regulation, the 59 untranslated region (UTR) of NIP5;1 was tested for its ability to confer B-dependent regulation using b-glucuronidase and green fluorescent protein as reporters. This analysis showed that the 59 UTR was involved in NIP5;1 transcript accumulation in response to B conditions. We also found that high-B conditions trigger NIP5;1 mRNA degradation and that the sequence from +182 to +200 bp in the 59 UTR is required for this mRNA destabilization. In the nip5;1-1 mutant background, a NIP5;1 complementation construct without the 59 UTR produced high levels of mRNA accumulation, increased B concentrations in tissues, and reduced growth under high-B conditions. These data suggest that the 59 UTR controls B-dependent NIP5;1 mRNA degradation and that NIP5;1 mRNA degradation is important for plant acclimation to high-B conditions. © American Society of Plant Biologists. All rights reserved.