Investigation of the regulation mechanism of Arabidopsis thaliana anion channel SLAH2

Abstract

In recent years a slow-type anion channel (SLAC) family composing five members, including slow anion channel associated 1 (SLAC1) and four SLAC1 homologs (SLAHs), has been identified in Arabidopsis thaliana. The anion channels are activated by calciumdependent protein kinases (CPKs) and play crucial roles in mediating anion fluxes across plasma membranes. SLAH2 is specifically expressed in root stele cells and has been characterized as a nitrate-selective anion channel activated by CPK21 and CBL-interacting protein kinase 23 (CIPK23). However, the interaction between CPKs and SLAH2 and how it is regulated remains to be elucidated. In this study we found that SLAH2 could be activated by a few CPKs from three subgroups of the CPK family. Out of those CPKs, the constitutively active form of CPK2 from subgroup 1 activates SLAH2, whereas the native as well as constitutively active form of CPK3 from subgroup 2 and CPK7, CPK10, and CPK32 from subgroup 3 activate SLAH2. We also explored the role of SLAH2 in root-toshoot nitrate transport by measuring the nitrate contents in xylem sap, but no significant differences were observed between the slah2-1 T-DNA insertion mutant and SLAH2 overexpression lines. Together, these data demonstrate that SLAH2 is regulated by multiple CPKs with variable Ca 2+ sensitivities. Further research is required to understand the role of SLAH2 in nitrate transport.

Calcium-Regulated Phosphorylation Systems Controlling Uptake and Balance of Plant Nutrients

“…− (Maierhofer et al, 2014a;Maierhofer et al, 2014b). Activation of these two SLAHs is also dependent on CBL1/9-CIPK23, and in addition, several members of the CPK family, such as CPK21 (Maierhofer et al, 2014a;Maierhofer et al, 2014b;Yao et al, 2017). Some members of the NRT/NPF or SLAH family are capable of transporting other ion species as well.…”

Guard Cell Membrane Anion Transport Systems and Their Regulatory Components: An Elaborate Mechanism Controlling Stress-Induced Stomatal Closure

“…SLAH2, on the other hand, is expressed mainly in roots, and shows S-type channel activity with strict nitrate selectivity [44]. CBL1-CIPK23 and several CPKs, including CPK3 and 21, were identified as the activator of this nitrate channel [44,160]. To this date, data on the function and expression of SLAH4 awaits discovery.…”