Interactive Effect of Arbuscular Mycorrhizal Fungi (AMF) and Olive Solid Waste on Wheat under Arsenite Toxicity

Heavy metal such as arsenite (AsIII) is a threat worldwide. Thus, to mitigate AsIII toxicity
on plants, we investigated the interactive effect of olive solid waste (OSW) and arbuscular mycorrhizal fungi (AMF) on wheat plants under AsIII stress. To this end, wheat seeds were grown in soils
treated with OSW (4% w/w), AMF-inoculation, and/or AsIII treated soil (100 mg/kg soil). AMF
colonization is reduced by AsIII but to a lesser extent under AsIII + OSW. AMF and OSW interactive
effects also improved soil fertility and increased wheat plants’ growth, particularly under AsIII stress.
The interactions between OSW and AMF treatments reduced AsIII-induced H2O2 accumulation. Less
H2O2 production consequently reduced AsIII-related oxidative damages i.e., lipid peroxidation (malondialdehyde, MDA) (58%), compared to As stress. This can be explained by the increase in wheat’s
antioxidant defense system. OSW and AMF increased total antioxidant content, phenol, flavonoids,
and α-tocopherol by approximately 34%, 63%, 118%, 232%, and 93%, respectively, compared to As
stress. The combined effect also significantly induced anthocyanins accumulation. The combination
of OSW+AMF improved antioxidants enzymes activity, where superoxide dismutase (SOD, catalase (CAT), peroxidase (POX), glutathione reductase (GR), and glutathione peroxidase (GPX) were
increased by 98%, 121%, 105%, 129%, and 110.29%, respectively, compared to AsIII stress. This can
be explained by induced anthocyanin percussors phenylalanine, cinamic acid and naringenin, and
biosynthesic enzymes (phenylalanine aminolayse (PAL) and chalcone synthase (CHS)). Overall, this
study suggested the effectiveness of OSW and AMF as a promising approach to mitigate AsIII toxicity
on wheat growth, physiology, and biochemistry.