Perturbed Leaf Development in Sorghum bicolor Exposed to Salinity: a Marker of Transition Towards Adaptation

Abstract

Pretreatment for 3 weeks with NaCl, within the range 35-150 mol m^-3, of 8 day old Sorghum bicolor cv. 610, results in adaptation of the plants to high salinity; plants become tolerant to 300 mol m^-3 NaCl, which is lethal for unadapted plants. During the adaptation period one or more developmentally perturbed leaves (DPL) may occur. DPL formation is positively correlated with the mean relative growth rate (RGR) of the plant following exposure to 300 mol m-3 NaCl, which reflects the degree of adaptation to high salinity. Treatments with exogenous phytohormones affect both DPL formation as well as the adaptation response. When plants 14 days old or more are exposed to salinity, neither adaptation nor DPL formation occurs, demonstrating the existence of a developmental window during which these phenomena may take place. These data suggest that DPL does not result from salt damage to the plant, but rather that it should be considered as a marker of the adaptation process.