title: CIPK23 is involved in iron acquisition of Arabidopsis by affecting ferric chelate reductase activity.
abstract: Iron deficiency is one of the major limiting factors affecting quality and production of crops in calcareous soils. Numerous signaling molecules and transcription factors have been demonstrated to play a regulatory role in adaptation of plants to iron deficiency. However, the mechanisms underlying the iron deficiency-induced physiological processes remain to be fully dissected. Here, we demonstrated that the protein kinase CIPK23 was involved in iron acquisition. Lesion of CIPK23 rendered Arabidopsis mutants hypersensitive to iron deficiency, as evidenced by stronger chlorosis in young leaves and lower iron concentration than wild-type plants under iron-deficient conditions by down-regulating ferric chelate reductase activity. We found that iron deficiency evoked an increase in cytosolic Ca(2+) concentration and the elevated Ca(2+) would bind to CBL1/CBL9, leading to activation of CIPK23. These novel findings highlight the involvement of calcium-dependent CBL-CIPK23 complexes in the regulation of iron acquisition. Moreover, mutation of CIPK23 led to changes in contents of mineral elements, suggesting that CBL-CIPK23 complexes could be as "nutritional sensors" to sense and regulate the mineral homeostasis in Arabisopsis.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Qiuying
authors.initials: Q
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: An
authors.initials: A
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Tianzuo
authors.initials: T
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China. Electronic address: whzhang@ibcas.ac.cn.
authors.forename: Wen-Hao
authors.initials: WH
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D038181:FMN Reductase / Q000378:metabolism*; D005816:Genetic Complementation Test; D007501:Iron / Q000494:pharmacology; D000090463:Iron Deficiencies; D009154:Mutation / Q000235:genetics; D018517:Plant Roots / Q000033:anatomy & histology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D058441:Rhizosphere
chemical_list: D029681:Arabidopsis Proteins; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; C514581:CIPK23 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D002118:Calcium
keywords: Arabidopsis; CIPK; Cytosolic Ca(2+) concentration; Ferric chelate reductase; Iron acquisition