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.

摘要

丛枝菌根真菌（AMF）共生可以在不利条件下促进植物生长。但是，很少有人研究过不同AMF种类之间在磷（Pb）污染土壤中增强磷（P）吸收能力和大豆耐受性的功能差异。因此，本研究旨在比较不同AMF定植的大豆植物的生长，对P的吸收和对Pb的耐受性，并测试在Pb污染的土壤中P吸收效率与Pb吸收之间的关系。大豆接种了三种不同的AMF，Funneliformis mosseae，Claroideoglomus etunicatum和Rhizophagus intraradices，并在三种Pb添加水平下（0、100和300 mg kg ^-1）进行锅内实验。结果表明，AMF接种显着促进了植物的生长，根部对P的吸收和Pb的积累，与未接种的植物相比，Pb从根到芽的转运较少。接种根瘤菌的大豆植株与其他两个AMF物种相比，在更高的根定植，生物量，P吸收和种子产量方面，Pb的耐受性更高。观察到植物的生物量，P吸收和Pb吸收之间存在显着的线性相关性。这项研究中的发现对于使用AMF促进重金属污染土壤中的大豆生长和磷吸收至关重要。此外，植物根系中共生磷的吸收和铅的保留可以作为筛选有效AMF物种或分离株以检测植物生长，磷营养和重金属污染土壤中金属耐受性的重要标准。