Stage-specific changes in hydrogen peroxide, membrane damage and antioxidant defense of a xerohalophyte fodder grass Panicum antidotale under increasing salinity

Information about reactive oxygen species (ROS) homeostasis during seed germination and early seedling stage of halophyte grasses is scant. This study examined the effects of increasing salinity on levels of hydrogen peroxide (H2O2, a common ROS), membrane damage and antioxidant defense during seed germination and early seedling stage of a C4 xerohalophyte fodder grass Panicum antidotale. Increases in salinity resulted in decreased seed germination. Contents of H2O2 and malondialdehyde (MDA, a common membrane damage marker) in germinating seeds increased with salinity, despite increased activities of most antioxidant enzymes. Whereas, high salinity resulted in decreased ascorbate and glutathione levels in germinating seeds. Growth of the early seedlings decreased with increases in salinity. Sap osmotic potential and chlorophyll content of the seedlings decreased with salinity increments. H2O2 content and activities of most antioxidant enzymes (except catalase) increased with increases in salinity. However, membrane integrity loss (an indicator of membrane damage) increased only at high (400 mM NaCl) but not at moderate (200 mM NaCl) salinity. These data indicate incidence of salinity-induced oxidative damage in both germinating seeds and seedlings of P. antidotale, especially under high salinity.