ARR6, a response regulator from Arabidopsis, is differentially regulated by plant nutritional status

The ARR6 gene, which has sequence similarity to bacterial response regulators, was isolated from Arabidopsis thaliana. The gene encodes a protein which is predicted to have two distinctive domains: a received er domain and an output domain. The ARR6 mRNA was predominantly expresssed in rosettes and it is almost undetectable in roots. Immunodetection of the ARR6 protein revealed that it responded to the nutritional status of the plant. It increased considerably, in both roots and rosettes, when the plants were deprived of an external phosphorus, nitrogen or potassium supply. ARR6 exhibited a sharp and transient increase in the roots within 2-4 days of deprivation for phosphorus, nitrogen or potassium. In rosettes from nutrient-deprived plants. the ARR6 protein rose to a maximum 6 days after deprivation, the last day it was measured. The somewhat parallel responses in ARR6 protein to nitrogen, phosphorus or potassium deprivation suggest that ARR6 responds to signals from a variety of nutrient sensors. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.