Calcium as a versatile plant signal transducer under soil water stress.

The complexity of calcium profiles observed in plant cells has led to the realization that specific patterns of calcium propagation (now termed calcium signatures) encode specific information and relay it to downstream elements (effectors) for translation into corresponding cellular responses in higher plants. The concept of calcium signatures is now well established and the tight control of the temporal and spatial characteristics of cytosolic calcium alterations is considered to be responsible for the specificity of various cellular responses, in particular to environment-induced stresses. To date, three major classes of plant calcium sensors responsible for drought-stress signal transduction during soil water deficit have been identified. Valuable pieces of the calcium signal-specificity puzzle are being put together and are illustrated here for the calcium-mediated signal-transduction cascades that operate in the responses of higher plants to soil environmental deficits. (c) 2008 Wiley Periodicals, Inc.