Structural and functional role of salt glands of cogon grass (Imperata cylindrica (L.) Raeuschel) under salinity stress

Abstract

Salt glands in Poaceae are often found in the Panicoid and Chloridoid grasses. Imperata cylindrica is a perennial panicoid grass with widespread distribution from non-saline to saline habitats. The efficient mechanism of salt gland is an essential property of the salt tolerance of any plant. Salt glands in Imperata are present and actively function to remove the toxic Na+ ion from the cytoplasm of the mesophyll cells. SEM study reveal the presence of salt glands in both control and NaCl treated plants (200 mM NaCl for 3 days), but the density of salt glands is more in NaCl treated leaf samples. Also the vacuolarization of the cells is an important attribute for the sequestration of excess Na+ ion. The concerted activity of these two mechanisms in Imperata is important for maintaining osmotic balance inside the cells. The time dependent lowering of H202 and O2 and increased accumulation of proline under NaCl stress was also observed in Imperata. This accounts for a favourable environment for other biological processes to occur. Also the lower electrolyte leakage and membrane lipid peroxidation accounts for hassle free functioning of salt glands under NaCl stress.