Physiological response of diverse halophytes to high salinity through ionic accumulation and ROS scavenging

Abstract

Salt stress induced modulations in different ionic ratios and ROS system were studied in ten halophytic species, namely Atriplex lentiformis, Tamarix aphylla, Sporobolus marginatus, Suaeda nudiflora, Urochondra setulosa, Arundo donax, Aeluropus lagopoides, Heliotropium ramossimum, Atriplex nummularia, Leptachloa fusca at salinity level of ECe - 30 dS/m (300 mM NaCl) to explore their possible role in salt tolerance ability of these halophytes. These halophytes were categorized for their salt tolerance levels based on the ratios of Na/K, Na/Ca, Na/Cl and Na + Cl/K + Ca. Variable responses were observed among all halophytes where Atriplex lentiformis had lowest leaf Na/K (0.44) which is one of the best indicator of salt tolerance, Heliotropium ramossimum had lowest Na/Ca and Na/Cl (0.97 and 0.18), whereas Sporobolus marginatus had lowest Na + Cl/K + Ca (0.79). Specific enzymes activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were also assessed to get better comprehension of the ROS scavenging system under salinity in these halophytes. Urochondra setulosa showed highest APX and SOD activity followed by Atriplex lentiformis. Most efficient enzyme in degrading hydrogen peroxide i.e. CAT showed highest activity in Suaeda nudiflora followed by Atriplex nummularia and Urochondra setulosa, whereas Atriplex nummularia and Atriplex lentiformis showed higher POX activity. Significant variability in H2O2 and MDA content was also observed. These results possibly suggest higher inbuilt genetic potential of these halophytes to combat high salinity induced oxidative stress via higher antioxidant activities.