EFFECT OF SALINITY STRESS ON YIELD, OIL QUALITY AND EXPRESSION OF DELTA 6-FATTY ACID DESATURASE (D6DES) GENE IN EVENING PRIMROSE (Oenothera biennis L.)

Evening primrose (Oenothera biennis L.) is grown commercially for seed oil, specially gamma-linolenic acid (GLA). Delta 6-fatty acid desaturase (D6DES) is a key gene for GLA biosynthesis. Salinity stress is one of the most important limiting factor in crop production. The aim of this study was to determine the effect of salinity levels (0, 20, 40, 60 and 80 mM) on yield and oil quality of Oenothera biennis. The result showed that there is the production possibility of the Oenothera biennis under salinity conditions up to 40 mM level, without significant changes in seed yield, oil content and fatty acid composition. Also, oil content and GLA were increased significantly at the 60 mM level, while seed yield was greater than 80 mM level. Therefore, there might be an opportunity for the economic production of the Oenothera biennis at the 60 mM level. The salinity stress in 60 mM and 80 mM levels decreased significantly plant height (PH), seed yield and yield components. The high salinity levels (60 mM and 80 mM) increased significantly the oil content and some compounds of fatty acids, such as palmitic acid (PA), stearic acid (SA) and GLA. The expression of D6DES gene in the middle and late-stages of seed post-flowering increased significantly under the highest salinity levels (60 mM and 80 mM). In the middle and late-stages of seed, there was positive correlation between the expression of D6DES and GLA content, which represents the conversion of linoleic acid (LA) to GLA.