The calcium sensor CBL10 mediates salt tolerance by regulating ion homeostasis in Arabidopsis

Abstract

). † These authors contributed equally to this work. SummaryCalcium 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.

A P IIB -type Ca 2+ -ATPase is essential for stress adaptation in Physcomitrella patens

“…Likewise, CBL genes are up-regulated by abiotic stress factors, and CBL4 and CBL10 act as calcium sensors required for the acquirement of salt tolerance (10)(11)(12) (1).…”

Tonoplast calcium sensors CBL2 and CBL3 control plant growth and ion homeostasis through regulating V-ATPase activity in Arabidopsis

“…Along this line, it is relevant to compare CBL2 and CBL3 with CBL10, another CBL that is targeted to tonoplast through a single transmembrane domain. The formation of CBL10-CIPK24 complex at the tonoplast mediates shoot salt tolerance by regulating unknown targets [20]. It will be important www.cell-research.com | Cell Research Another interesting observation is that the cbl2 cbl3 mutant has a higher K + content than the wild type.…”

“…Through forward genetic screens, the CBL Ca 2+ sensor SOS3 (for Salt Overly Sensitive 3)/CBL4 and CIPK-type kinase SOS2/CIPK24 have been identified as key components in a Ca 2+ -signaling pathway that specifically mediates salt stress adaptation by regulating the Na + /H + antiporter SOS1 at the plasma membrane [11,[16][17][18]. Further studies indicated that another CBL member, CBL10, also interacts with CIPK24/SOS2 to protect Arabidopsis shoots from salt stress [19,20]. In response to low-K + status, CIPK23 is activated and recruited to the plasma membrane by Ca 2+ sensors CBL1 and CBL9, and the CBL-CIPK23 complexes activate the shaker-like K + channel AKT1 for optimal K + uptake under limiting K + supply conditions [21][22][23].…”

“…While CBL1 and CBL9 harbor motifs for N-myristoylation and S-acylation that anchor them to the plasma membrane and target their function towards regulation of transporters [21][22][23]30], several other CBL members, including CBL2, CBL3, CBL6 and CBL10, contain variable N-terminal extensions that target the proteins specifically to the vacuolar membranes [20,28]. As discussed above, substantial progress has been made in characterizing plasma membrane-targeted CBL proteins such as CBL1, CBL4 and CBL9.…”

Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

“…The 20-fold induced CBL-interacting serine/threonine-protein kinase has high similarity with the Arabidopsis CALCI-NEURIN B-LIKE10/SOS3-LIKE CALCIUM BINDING PROTEIN8 (SCABP8), a Ca 2? -interacting protein kinase that mediates salt stress tolerance in shoots via the salt overly sensitive (SOS) pathway [84,85]. Salt induces CBL10 phosphorylation by SOS2, which stabilizes the CBL10-SOS2 interaction and enhances the activity of the Na ?…”