Reduction of arsenic accumulation in rice grain by endophytic fungus Serendipita indica

Arsenic contamination in rice is a major health concern that affects millions of people worldwide. Several strategies are recommended to reduce arsenic in rice, with AMF being one of the most important and cost-effective. This work is a pot study under environmental condition on rice plants under arsenic (AsV) treatment to demonstrate the ameliorative property of axenically cultivable AMF Serendipita indica (S. indica) in arsenic stress and accumulation in colonised plants. Colonisation of S. indica is 12 times higher under arsenic stress which is correlated to improved growth, biomass, and yield in fungal-colonised plants compared to arsenic-treated plants. Fungal colonisation results in a 1.9 times reduction in H2O2 content with the induction of the antioxidative enzyme system, proline and glutathione levels (up to 1.5 times). The fungal colonisation results in the recovery of pigment content (Chl a, Chl b and carotenoids) with improved photosynthesis, transpiration, and water use efficiency under arsenic stress. S. indica colonisation in plant roots resulted in a massive accumulation of arsenic (31.5 ppm) in the root leading to reduced arsenic mobilisation from the root to shoot, husk and grains. The restriction of arsenic in the root by the fungus was due to the modulation in iron (Fe) partitioning, resulting in the protection of the plant from arsenic stress and reduced level of arsenic in the grain. We show that using axenically cultivable fungus S. indica in highly arsenic-contaminated agricultural soil may reduce arsenic stress and accumulation in rice plants through modulation in Fe homeostasis.