Water Deficit in Pea Root Tips: Effects on the Cell Cycle and on the Production of Dehydrin-like Proteins

Dehydrin-like proteins have been detected in nuclei and cytoplasm of meristematic root tip cells from pea seedlings subjected to slow dehydration at 90% relative humidity for 48 h or more. Evidence was gained from Western blotting and immunocytochemical experiments using an antibody raised against the conserved domain of dehydrin proteins. Flow cytometer analysis has shown that cycling cells of root tip meristems from dehydrated seedlings are mostly arrested in G2 phase. Other stress treatments thought to involve water depletion (osmotic stress, cold treatment) or to modulate cell response to water deficit (abscisic acid) gave less clear-cut results with all treatments lowering the proportion of cells entering the S phase, but without a definite and persistent arrest in any preferential phase of the cycle. Possible interrelationships between G2 arrest and dehydrin production are discussed.