Arbuscular mycorrhizal fungi species differentially regulate plant growth, phosphorus uptake and stress tolerance of soybean in lead contaminated soil

Abstract

Arbuscular mycorrhizal fungi (AMF) symbiosis can enhance plant growth in unfavorable conditions. However, functional variations among different AMF species for their ability to enhance phosphorus (P) uptake and soybean tolerance in lead (Pb) contaminated soil have rarely been examined. The present study therefore aimed to compare the growth, P uptake and Pb tolerance of soybean plants colonized by different AMF and to test the relationship between P uptake efficiency and Pb uptake in Pb contaminated soil. Soybean inoculated with three different AMF, Funneliformis mosseae, Claroideoglomus etunicatum, and Rhizophagus intraradices and control was grown under three Pb addition levels (0, 100 and 300 mg kg−1) in a pot experiment. The results showed that AMF inoculation significantly promoted the plant growth, P uptake and Pb accumulation in the roots, with less translocation of Pb from roots to the shoots compared to non-inoculated plants. Soybean plants inoculated with R. intraradices were more tolerant to Pb toxicity compared with other two AMF species in terms of higher root colonization, biomass, P uptake and seed yield. Significant linear correlations were observed between biomass, P uptake and Pb uptake of the plant. The findings in this study are essential in using AMF to promote soybean growth and P uptake in heavy metal-contaminated soils. Moreover, symbiotic P uptake and retention of Pb in roots of plants could serve as important criteria for screening of efficient AMF species or isolates for plant growth, P nutrition and metal tolerance in heavy metal contaminated soils.