Effects of Exogenous Linoleic Acid on Barley (Hordeum vulgare L.) Seedlings Under Salinity

Abstract

Salt stress adversely affects plants and causes different levels of morphological, physiological, biochemical, and molecular changes at different growth stages. Polyunsaturated fatty acids (PUFAs), such as linoleic acid, are main components of membrane lipids and determine the fluidity and stability of the cell membrane. In addition, PUFAs have a crucial role in maintaining the structure and function of the cell membrane which is damaged by salinity. There may be a relationship between level of PUFAs in membrane lipids and salinity tolerance. The present study was carried out to examine the effects of exogenous application of 0.5 mM linoleic acid (LA) on barley seedlings (Hordeum vulgare L. cv. Martı) grown in hydroponic conditions under 160 mM NaCl. The treatment with LA ameliorated the stress generated by NaCl by increasing osmolyte level and decreasing ion leakage percentage and H2O2 content within hours. Besides, LA significantly enhanced expression of salt-responsive transcription factor HvDRF2 and ROS scavenger gene HvMT2 as 105- and 40-fold, respectively, in the leaves of barley seedlings under salinity conditions. While LA slightly increased the gene expression of ascorbate peroxidase (HvAPX), glutathione S-transferase (HvGST6) and copper zinc superoxide dismutase (HvCu/ZnSOD) in the roots of barley seedlings, the expression of these genes was not changed in the leaves under salinity compared to salt-stressed samples. This study provides novel insights for effects of LA on improvement of salinity tolerance in barley.