Center for Desert Agriculture, King Abdullah Unicersity of Science and Technology, Kingdom of Saudi Arabia
Nitric oxide (NO) and reactive oxygen species (ROS) are key signaling molecules in plant defense against biotic and abiotic stress response and developmental processes. Various stimulants trigger the burst of NO and ROS in plants, activating downstream signaling cascades to combat biotic and abiotic stresses. S-nitrosoglutathione-reductase 1 (GSNOR1) plays a significant role in NO and S-nitrosothiol (SNO) regulation and homeostasis. We investigated the effect of AtGSNOR1 in Arabidopsis on salinity tolerance using AtGSNOR1 overexpressing (OEX) and Atgsnor1 knockout (KO) lines grown hydroponically in control conditions and at two different salinity levels. We found that AtGSNOR1 KO lines are more salt tolerant than the wild type (WT) and OEX lines, as measured by the ability of plants to maintain growth (fresh weight) in saline conditions relative to control conditions. Moreover, KO mutant lines accumulate less Na+ in the shoots than WT and OEX lines under saline stress conditions. In addition, KO mutant lines have a lower Na+/K+ ratio than WT and OEX lines. These analyses of AtGSNOR1 OEX and KO lines in hydroponic conditions suggest that AtGSNOR1 negatively regulates salt tolerance in Arabidopsis plants. Taken together, we propose that increased NO levels due to the loss-of-function of AtGSNOR1 could activate subcellular and tissue specific Na+ detoxification mechanisms leading to reduced sodium accumulation in the shoot and increased salinity tolerance.
Keywords: AtGSNOR1, NO, Salinity.