Myco-remediation for Chromium Stress Alleviation to Improve Maize (Zea mays L.) Physiology and Biochemistry by Seeds Bio-priming with Aspergillus niger strain PMI-1811

Abstract Metal toxicity has a wide range of direct and indirect effects on plants, affecting nearly all physiological functions. Three different maize cultivars were grown under various chromium stress levels to study the response of Aspergillus niger PMI-1811 to ameliorate the adverse effects of the metal. The aim of the current study is to develop metal tolerance in cereal crops and an increase in maize productivity in Cr stress. A completely randomized design with three replicates of three maize cultivars, chromium levels, control and fungal spore suspension was used as treatment for the plants. Fungi facilitates efficient ammonia production (4.09 ± 0.373, 2.09 ± 0.644 µmol/mL), phosphate solubilization (2.48 ± 0.1 SI) and indole acetic acid (64.83 ± 2.494, 43.91 ± 1.166 µg/mL)) synthesis during in-vitro (control, stress) condition to promote plant health under chromium stress. In this study, Aspergillus niger PMI-1811 assisted the phytoremediation of chromium and improve stress tolerance in various maize ( Zea mays L.) cultivars as improved plant length (45.45%) and biomass (47.29%) compared to the untreated plants. Chlorophyll (29.52%), ascorbic acid (89.66%) and other biochemical parameters were increased when compared to the uninoculated plants. Fungal inoculation reduced the accumulation of malondialdehyde (15.73%), hydrogen peroxide (13.64%) and lowered the activity of antioxidant enzymes catalase (17.86%), ascorbate peroxidase (40.43%) and peroxidase (26.32%). Moreover, fungal inoculation increased the levels of minerals K (60.46%), Ca (108.82%) and reduced Cr bioaccumulation in shoots (39.45%) and roots (46.59%). Together, the uncovering of A. niger's involvement in nutrient uptake opens up new avenues for the agricultural application. In chromium-contaminated soil A. niger could be employed for agricultural productivity and ecological restoration.