Role of Native Arbuscular Mycorrhizal Fungi in Modulating Nutrient Subcellular Distribution in Wheat Grown in Mn-Toxic Soil

Abstract

Heavy metal toxicity leads to impaired crop growth and reduced crop yields and product quality by disrupting plant nutrient uptake, inhibiting development, inducing oxidative stress, and causing cellular toxicity. Arbuscular mycorrhizal fungi (AMF) can play a crucial role in crops’ adaptation to manganese (Mn) toxicity by regulating nutrient uptake and altering subcellular compartmentalization. The present study examines the in- fluence of intact extraradical mycelia (ERMs) from native AMF on wheat (Triticum aestivum) grown in Mn-toxic soil, with a focus on the tissue-specific and subcellular Ca, Mg, P, and Mn distribution. Wheat cultivated in soil pre-colonized using an intact ERM associated with Lolium rigidum or Ornithopus compressus exhibited enhanced growth and improved P contents. During the first week of growth, the Mn concentrations increased in the wheat’s roots and shoots, but Mn was subsequently reduced and sequestered within the cell wall. In contrast, in the absence of an intact ERM, the Mn accumulation in wheat followed an apparent continuous time-course pattern. AMF-mediated cell wall sequestration seems to contribute to Mn detoxification by limiting excessive cytoplasmic accumulation. Fur- thermore, AMF-driven changes in the element distribution suggest a dynamic response, wherein an early-stage nutrient uptake transitions into a long-term protective mechanism. These findings highlight the potential of AMF in mitigating Mn stress in crops, providing insights for sustainable agriculture and soil remediation strategies.