title: Phosphorylation of ARF2 Relieves Its Repression of Transcription of the K+ Transporter Gene HAK5 in Response to Low Potassium Stress.
abstract: Potassium (K+) plays crucial roles in plant growth and development. In natural environments, K+availability in soils is relatively low and fluctuating. Transcriptional regulation of K+transporter genes is one of the most important mechanisms in the plant's response to K+deficiency. In this study, we demonstrated that the transcription factor ARF2 (Auxin Response Factor 2) modulates the expression of the K+transporter gene HAK5 (High Affinity K+transporter 5) in Arabidopsis thaliana The arf2 mutant plants showed a tolerant phenotype similar to the HAK5-overexpressing lines on low-K+medium, whose primary root lengths were longer than those of wild-type plants. High-affinity K+uptake was significantly increased in these plants. ARF2-overexpressing lines and the hak5 mutant were both sensitive to low-K+stress. Disruption of HAK5 in the arf2 mutant abolished the low-K+-tolerant phenotype of arf2 As a transcriptional repressor, ARF2 directly bound to the HAK5 promoter and repressed HAK5 expression under K+sufficient conditions. ARF2 can be phosphorylated after low-K+treatment, which abolished its DNA binding activity to the HAK5 promoter and relieved the inhibition on HAK5 transcription. Therefore, HAK5 transcript could be induced, and HAK5-mediated high-affinity K+uptake was enhanced under K+deficient conditions. The presented results demonstrate that ARF2 plays important roles in the response to external K+supply in Arabidopsis and regulates HAK5 transcription accordingly.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Tian-Li
authors.initials: TL
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China yiwang@cau.edu.cn.
authors.forename: Yi
authors.identifier: 0000-0002-3660-5859
authors.initials: Y
authors.lastname: Wang
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism*; D027961:Potassium-Hydrogen Antiporters / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C503421:ARF2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D027961:Potassium-Hydrogen Antiporters; D012097:Repressor Proteins; C501258:potassium transporter, Arabidopsis; D011188:Potassium