The Combined Effects of Rhizobacteria and Methyl Jasmonate on Rosmarinic Acid Production and Gene Expression Profile in Origanum Vulgare l. Under Salinity Conditions

摘要

Origanum vulgare L. is a valuable flavoring, mainly due to its important essential oils and is widely used in different industries. This study aimed to compare the expression level of genes coding for proteins involved in rosmarinic acid (RA) biosynthesis pathway and some physiological responses in O. vulgare under two levels of salinity (2, 4 decisiemens/meter (dS/m), and 0 as a control), two levels of Methyl Jasmonate (MeJA) (0.1, 0.5 mM, and 0 as a control), and a consortium of three bacteria (Azotobacter chroococcum, Azospirillium brasilense, and Pseudomonas fluorescens). The results showed that salinity negatively affected RA induction and rosmarinic acid synthase (RAS) gene expression and positively influenced DPPH radical scavenging capacity at all treatments. The combined application of bacterial consortium and 0.1 mM MeJA in absence of salinity showed 6.6- and 3.37-fold cinnamic acid 4-hydroxylase (C4H), RAS genes expression, respectively, compared to control. Application of bacterial consortium and 0.1 mM MeJA also increased RA induction (6.47 mg/g), total phenolic content (6.79 mg GAE/g), and positively affected all biochemical and physiological treats in O. vulgare. MeJA in concentration of 0.5 mM even with bacteria inoculation had negative effect on RA production. The RAS gene may be more responsible for controlling RA induction compared to C4H gene. Further studies are needed to identify all genes involved in RA production in O. vulgare. Our results may be used to improve RA production and tolerance mechanisms of O. vulgare under salinity conditions.