Recent Advances in Understanding the Regulation of Whole-Plant Growth Inhibition by Salinity, Drought and Colloid Stress

This chapter presents an eclectic perspective, based largely on research findings from our laboratory on biochemical and biophysical mechanisms involved in growth inhibition by water deficits, as caused by salinity (Section II), drought (Section III) and recently reported plant interactions with aqueous colloids found in soil solutions or xylem sap (Section IV). Much attention in each section is given to the roles of plant cell walls in regulating whole-plant growth inhibition under stressful conditions. One conclusion is that ongoing research into genomic and epigenetic changes that participate in the regulation of cell wall changes, cellular antioxidant status and plant hydraulics may provide new approaches for limiting the plant growth inhibition or mortality associated with salinity and drought. In Section IV, it is concluded that the 'colloid stress' that results from the inhibitory effects on water transport of physical interactions between plant cell walls and environmental or internal colloids is a novel stress-factor that can affect plant water relations and further limit plant ability to resist salinity and drought.