The cyclic nucleotide‐gated channel, AtCNGC10, influences salt tolerance in Arabidopsis

Cyclic nucleotide‐gated channels (CNGCs) in the plasma membrane transport K + and other cations; however, their roles in the response and adaptation of plants to environmental salinity are unclear. Growth, cation contents, salt tolerance and K + fluxes were assessed in wild‐type and two AtCNGC10 antisense lines (A2 and A3) of Arabidopsis thaliana (L.) Heynh. Compared with the wild‐type, mature plants of both antisense lines had altered K + and Na + concentrations in shoots and were more sensitive to salt stress, as assessed by biomass and Chl fluorescence. The shoots of A2 and A3 plants contained higher Na + concentrations and significantly higher Na + /K + ratios compared with wild‐type, whereas roots contained higher K + concentrations and lower Na + /K + ratios. Four‐day‐old seedlings of both antisense lines exposed to salt stress had smaller Na + /K + ratios and longer roots than the wild‐type. Under sudden salt treatment, the Na + efflux was higher and the K + efflux was smaller in the antisense lines, indicating that AtCNGC10 might function as a channel providing Na + influx and K + efflux at the root/soil interface. We conclude that the AtCNGC10 channel is involved in Na + and K + transport during cation uptake in roots and in long‐distance transport, such as phloem loading and/or xylem retrieval. Mature A2 and A3 plants became more salt sensitive than wild‐type plants because of impaired photosynthesis induced by a higher Na + concentration in the leaves.