title: A protein kinase, calcineurin B-like protein-interacting protein Kinase9, interacts with calcium sensor calcineurin B-like Protein3 and regulates potassium homeostasis under low-potassium stress in Arabidopsis.
abstract: Potassium (K⁺) is an essential macronutrient for plant growth and development. Previous studies have demonstrated that Calcineurin B-Like Protein1 (CBL1) or CBL9 and CBL-Interacting Protein Kinase23 (CIPK23) regulate K⁺ uptake in Arabidopsis (Arabidopsis thaliana) roots by modulating K⁺ channel Arabidopsis K⁺ Transporter1. In this study, we show that the protein kinase CIPK9 interacts with the calcium sensor CBL3 and plays crucial roles in K⁺ homeostasis under low-K⁺ stress in Arabidopsis. Arabidopsis wild-type plants showed leaf chlorotic symptoms when grown for 10 d on low-K⁺ (100 μM) medium. Here, we show that plants lacking CIPK9 displayed a tolerant phenotype to low-K⁺ stress, which still maintained green leaves when the wild-type plants showed typical K⁺-deficient symptoms. Overexpressing lines of CIPK9 resulted in a low-K⁺-sensitive phenotype compared with wild-type plants. Furthermore, CBL2 and CBL3 were identified as upstream regulators of CIPK9. Both CBL2- and CBL3-overexpressing lines displayed similar low-K⁺-sensitive phenotypes and K⁺ contents to CIPK9-overexpressing lines. However, only cbl3 mutant plants, but not cbl2 mutant plants, showed the low-K⁺-tolerant phenotype similar to cipk9 mutants. Taken together, these results demonstrate that CIPK9 and CBL3 work together and function in K⁺ homeostasis under low-K⁺ stress in Arabidopsis.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Liu
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Ren
authors.forename: Li-Qing
authors.initials: LQ
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Wu
mesh_terms: D000222:Adaptation, Physiological; D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003470:Culture Media / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D006706:Homeostasis; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011523:Protoplasts / Q000378:metabolism; D013312:Stress, Physiological; D059467:Transcriptome; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D003470:Culture Media; D011188:Potassium; D015221:Potassium Channels; D017346:Protein Serine-Threonine Kinases; C480758:At5g55990 protein, Arabidopsis; C484079:CBL3 protein, Arabidopsis; C523347:CIPK9 protein, Arabidopsis