Toxic effect of NaCl on ion metabolism, antioxidative enzymes and gene expression of perennial ryegrass.

Two-month old seedlings of perennial ryegrass (Lolium perenne L.) were subjected to four different levels of salinity for 7 days. The NaCl treatments reduced turf quality and normalized transpiration rates. Both chlorophyll (Chl) a and Chl b contents decreased in the grass exposed to 255 mM relative to the control. An increase in the lipid peroxidationin was observed. The activity of leaf superoxide dismutase increased while, peroxidase and catalase activities decreased in response to NaCl treatments. The expression of Chl Cu/ZnSOD, Cyt Cu/ZnSOD, FeSOD, CAT, POD, GPX and GR was up-regulated for NaCl-treated grass. Salt stress increased accumulation of Na(+) and decreased K(+)/Na(+) ratio, Mg(2+) and P content in both shoots and roots of perennial ryegrass. The findings of this study suggest that salt stress may cause toxicity to perennial ryegrass through oxidative injury and damage to Chl and cell membrane integrity.