Effects of Water Stress on Elongation Growth of Maize Coleoptiles

Abstract

Water stress (25% water saturation) inhibits coleoptile howth in maize but at the same time dramatically increases osmotic potential indicating that water stress inhibits growth even at elevated turgor pressure. Direct rheological measurements of cell wall extensibility using an electronic extensiometer showed that water stress reduced cell wall extensibility. Water stress greatly improves the ability of coleoptiles to elongate in response to auxin. It is concluded that water stress inhibits coleoptile growth by interfering with auxin metabolism leading to the stiffening of growth limiting cell walls by reducing their extensibility. The water stress-induced inhibition of in-vivo extensibility is entirely due to the reduction of plasticity (Ep1) rather than the elasticity(Ee1) of cell walls.