Use of Arbuscular Mycorrhizal Fungi for Boosting Antioxidant Enzyme Metabolism and Mitigating Saline Stress in Sweet Basil (Ocimum basilicum L.)

Salinity is one of the outstanding abiotic stress conditions that a significant part of the world faces. In recent years, beneficial microorganisms started to be utilized in plants to overcome several abiotic factors, including salinity. The effects of arbuscular mycorrhizal fungi (AMF) mixture on growth and enzymatic responses in basil under salt stress were investigated using saline doses of 0 mM (Control), 150 mM, and 300 mM. Results showed that AMF enhanced all growth parameters, but only the leaf number was statistically significant. However, antioxidant enzymes, such as ascorbate peroxidase (APX) by 25%, catalase (CAT) by 25%, and superoxide dismutase (SOD) by 5%, significantly enhanced. At the same time, the accumulation of oxidative enzymes, like hydrogen peroxide (H2O2) and malondialdehyde (MDA), was reduced, from 12.05 μmol g−1 fw (control) to 11.17 μmol g−1 fw (AMF) and from 14.29 μmol g−1 fw to 10.74 μmol g−1 fw, respectively. AMF also significantly alleviated the chlorophyll loss caused by increasing saline doses. Multivariate analyses revealed the co-occurrence of stress metabolism enzymes as well as the proximate effect of AMF inoculation on basil yield and enzymatic activity. As a result, AMF was considered an appropriate tool for increasing growth and reducing salt stress under both stress-free and saline conditions