The Transcription Factor MYB59 Regulates K/NO Translocation in the Arabidopsis Response to Low K Stress.

Potassium and nitrogen are essential nutrients for plant growth and development. Plants can sense potassium nitrate (K/NO ) levels in soils, and accordingly they adjust root-to-shoot K/NO transport to balance the distribution of these ions between roots and shoots. In this study, we show that the transcription factorMYB59 maintains this balance by regulating the transcription of the Arabidopsis () ()/ () in response to low K (LK) stress. The mutant showed a yellow-shoot sensitive phenotype when grown on LK medium. Both the transcript and protein levels of were remarkably reduced in the mutant. LK stress repressed transcript levels of both and The and mutants, as well as the double mutant, showed similar LK-sensitive phenotypes. Ion content analyses indicated that root-to-shoot K/NO transport was significantly reduced in these mutants under LK conditions. Moreover, chromatin immunoprecipitation and electrophoresis mobility shift assay assays confirmed that MYB59 bound directly to the promoter. Expression of in root vasculature driven by the promoter rescued the sensitive phenotype of both and mutants. Together, these data demonstrate that responds to LK stress and directs root-to-shoot K/NO transport by regulating the expression of in Arabidopsis roots.