Analysis the Expression Patterns of Genes Encoding Antioxidative Enzymes under Salt Stress in Date Palm (Phoenix dactylifera)

Salt stress is one of the major environmental factor limiting crop production. Plants under salt stress face several physiological problems including ionic toxicities, osmotic stress and oxidative damage.

Under salt stress, Reactive Oxygen Species (ROS) are by-products of physiological metabolisms, that are significantly accumulated, cause oxidative damage and kill the cell. To avoid the deleterious effects of salt stress, plants develop a mechanism to detoxify reactive oxygen species and avoid oxidative damage of different cellular components including DNA and various proteins. Therefore, plants activate many stress-responsive genes and synthesis diverse of functional proteins like ascorbate (AsA), glutathione (GSH), as well as anti-oxidative enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT).

The aim of the current study was to analyze the expression patterns of date palm genes encoding antioxidative enzymes under different levels of salt stress. Results showed notable induction of PdCAT, PdGR, PdMDAR, PdSOD and PdAPX. At 100 mM NaCle, both PdCAT and PdGR showed the highest induction while PdMDAR was able to keep its highest expression at up to 400 mM NaCl. Using different salt exposure time course, all genes sustained up-regulated expression levels up to 6 days compared to control conditions. In addition, high and steady induction of glutathione S-transferase (PdGST) was observed. This enzyme plays key roles in the detoxification of xenobiotics compounds and oxidative stress mechanism. Our results conclude that antioxidative enzymes involved in either ROS detoxification or antioxidants regeneration could have crucial roles in salt stress tolerance of date palm.