title: The calcium sensor CBL10 mediates salt tolerance by regulating ion homeostasis in Arabidopsis.
abstract: Calcium serves as a critical messenger in many adaptation and developmental processes. Cellular calcium signals are detected and transmitted by sensor molecules such as calcium-binding proteins. In plants, the calcineurin B-like protein (CBL) family represents a unique group of calcium sensors and plays a key role in decoding calcium transients by specifically interacting with and regulating a family of protein kinases (CIPKs). We report here that the CBL protein CBL10 functions as a crucial regulator of salt tolerance in Arabidopsis. Cbl10 mutant plants exhibited significant growth defects and showed hypersensitive cell death in leaf tissues under high-salt conditions. Interestingly, the Na(+) content of the cbl10 mutant, unlike other salt-sensitive mutants identified thus far, was significantly lower than in the wild type under either normal or high-salt conditions, suggesting that CBL10 mediates a novel Ca(2+)-signaling pathway for salt tolerance. Indeed, the CBL10 protein physically interacts with the salt-tolerance factor CIPK24 (SOS2), and the CBL10-CIPK24 (SOS2) complex is associated with the vacuolar compartments that are responsible for salt storage and detoxification in plant cells. These findings suggest that CBL10 and CIPK24 (SOS2) constitute a novel salt-tolerance pathway that regulates the sequestration/compartmentalization of Na(+) in plant cells. Because CIPK24 (SOS2) also interacts with CBL4 (SOS3) and regulates salt export across the plasma membrane, our study identifies CIPK24 (SOS2) as a multi-functional protein kinase that regulates different aspects of salt tolerance by interacting with distinct CBL calcium sensors.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Beom-Gi
authors.initials: BG
authors.lastname: Kim
authors.forename: Rainer
authors.initials: R
authors.lastname: Waadt
authors.forename: Yong Hwa
authors.initials: YH
authors.lastname: Cheong
authors.forename: Girdhar K
authors.initials: GK
authors.lastname: Pandey
authors.forename: Jose R
authors.initials: JR
authors.lastname: Dominguez-Solis
authors.forename: Stefanie
authors.initials: S
authors.lastname: Schültke
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Lee
authors.forename: Jörg
authors.initials: J
authors.lastname: Kudla
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis; D052139:Intracellular Calcium-Sensing Proteins / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism