The biomass and health-enhancing qualities of lettuce are amplified through the inoculation of arbuscular mycorrhizal fungi

With lettuce being one of the most important green crops in the world, it is important to improve its growth and nutritive value. To this end, arbuscular mycorrhizal fungus (AMF) application to improve nutrient-dense foods and the production of bioactive compounds in plants is a promising approach. AMF is applied to increase plant growth, primary metabolism, mineral profile and accumulation of secondary (phenols, flavonoids) metabolites. AMF treated plants showed increased biomass accumulation by 38.8%. This increase was in line with increased levels of photosynthesis rate and the total chlorophyll content by approximately 28.8%, respectively. In nutritive value, AMF increased mineral profile, vitamin contents and carbohydrate as indicated by D-mannose, L-galactose, and vitamin E (p < 0.05) by approximately 32.7%, 25%, and 46.6%, respectively. The AMF-treated lettuce's proximate composition revealed considerably greater levels of total protein (7.8%), as well as crude fiber, ash, and carbohydrates (about 7%) compared to control samples (p < 0.05). Furthermore, AMF inoculation increased levels of antioxidants, essential amino acids, and unsaturated fatty acids. It increased the levels of antioxidants such as alpha and beta carotene, polyphenols, which was correlated with increased phenylalanine ammonia-lyase (PAL) enzyme activity. Treatment with AMF resulted in an increase of more than 76% of the detected amino acids, with the highest increment observed for isoleucine, methionine and biosynthetic enzyme (cystathionine γ-synthase (CGS)), and which were 200%, 270.2%, and 153.5%, respectively. Increased bioactive accumulation also resulted in improved antioxidant and antidiabetic and antibacterial activities against a variety of pathogenic microorganisms. The findings indicate that the AMF treatment is a feasible method for enhancing lettuce's biological characteristics and health-promoting attributes.