Effects of Mycorrhizal Fungi and Methyl Jasmonate on Salt Stress Tolerance and Phytochemical Traits of Satureja Khuzistanica

Savory (Saturja khuzistanica) is a precious medicinal plant. This species contains essential oil and its extract is widely used in various industries. This study investigate the simultaneous effects of Arbuscular mycorrhizal fungi (AMF) and methyl jasmonate (MeJA) on Satureja Khuzistanica tolerance, physiological and biochemical traits under salt stress. The experiment designed as a completely randomized factorial with two AMF levels, including the combination of AMF (Glomus intraradices and G. fasciculatum species) and without inoculation, four levels of salt (0, 3, 6, and 9 dS/m) and three concentrations of MeJA (0, 60 and 120 µM). The results indicated that salt stress had adverse effects on the savory plant. Salinity caused a significant impact on physiological and biochemical traits (including chlorophyll pigments, proline, sugar, protein, N, P+, K+, Ca2+, Mg2+, Na+) (P ≤ 0.01). The savory plant had the best performance under AMF + 60 µM MeJA treatments at saline and non-saline condition. The findings showed that the highest salt level (9 dS/m) caused a remarkable inhibition on the amounts of flavonoid, total phenol, and antioxidant activity in savory extract and essential oil, even under AMF and MeJA treatments. AMF symbiosis had better performance in the synthesis of all phytochemical parameters. MeJA at 60 µM concentration had the most positive effects on the phytochemical parameters of savory plants at all salt levels, such as AMF-treated and non-treated plants. The highest flavonoid content in the savory essential oil was induced at AMF + 60 µM MeJA + 6 dS/m salt treatment (1.02%). The highest amounts of total phenol (8.12%, 8.14%) and antioxidant activity (59.21%, 59.25%) in Satureja essential oil were observed at AMF + 60 µM MeJA + 3 and 6 dS/m salt treatments; there was no significant difference between 3 and 6 dS/m salt at this treatment. There was lower flavonoid content in the essential oil of S. khuzistanica than in its extract. But savory essential oil had higher amounts of total phenol rather than its extract. Applying AMF and MeJA seems to be a cost-effective way to improve physiological characteristics and antioxidant capacity in savory plants under saline conditions.