A calcium sensor homolog required for plant salt tolerance.

Excessive sodium (Na+) in salinized soils inhibits plant growth and development. A mutation in the SOS3 gene renders Arabidopsis thaliana plants hypersensitive to Na+-induced growth inhibition. SOS3 encodes a protein that shares significant sequence similarity with the calcineurin B subunit from yeast and neuronal calcium sensors from animals. The results suggest that intracellular calcium signaling through a calcineurin-like pathway mediates the beneficial effect of calcium on plant salt tolerance.