The differential physiological mechanism and ecological response of Pisolithus sp. mycorrhizal Pinus thunbergii to Chromium

Abstract Aims Pisolithus sp. as a class of ectomycorrhizal (ECM) fungi with multiple HM tolerance. However, the physiological mechanism and ecological response of Pisolithus sp. ECM plants to chromium (Cr) remain unclear. Pisolithus sp.1 (Cr tolerant strain) and Pisolithus sp.2 (Cr sensitive strain) ECM Pinus thunbergii were synthesized to explore their different physiological and ecological response to Cr in this work. Methods Biomass, nutrient elements and Cr concentration of plants; Cr form and content in soil; Physicochemical properties, enzyme activities and microbial high-throughput analysis of soil were performed by pot and acute exposure experiments. Results The growth and Cr tolerance of P. thunbergii were improved after been inoculated with Pisolithus sp.1 by reducing the transportation of Cr from roots to shoots, increasing the N assimilation rates of host through mycelium, and enhancing the available phosphorus (P) and enzyme activities in soil. The above-mentioned process were co-driven by the fungi in Basidiomycetes and Ascomycota phylum, the predominant bacteria Brevundimonas sp., Muribaculaceasand Lachnospiraceae, as well as hexavalent chromium (Cr(VI)) tolerant and reducing strain Simplicillium and Pichia. Pisolithussp.2 promoted the Mg accumulation in shoots of host and increased the abundance of Gibberella, Mortierella and Didymella in soil, which accelerated the P solubilization in soil and nutrient transformation in host to response to Cr. Conclusions Our results showed that Pisolithussp.1 ECM P. thunbergii had high adaptability to Cr, and this work also have an important theoretical guiding significance and application value for mycorrhizal phytoremediation of Cr-contaminated soil.