Isolation and identification of arbuscular mycorrhizal fungi from high phosphate soils

Abstract:

[Background] Arbuscular mycorrhizal (AM) fungi have a wide range of host species, environmental adaptation and remarkable plant growth-promoting capability. However, high phosphate level in soils has seriously inhibited the growth of AM fungi and the AM formation. [Objective] This study aimed to isolate and identify indigenous AM fungal strains resistant to high phosphate in south China, and to provide novel materials for mycorrhiza research. [Methods] The AM fungi from high phosphate soils were identified by classical morphology and molecular systematics. [Results] Twenty-five AM fungi species belonging to 7 genera were identified from root-zone soils with the available phosphorus concentration of 53-131 (88.2±17.6 as average±SD) mg/kg, including 12 species in Acaulospora, 7 in Glomus, 2 in Septoglomus, 1 in Claroideoglomus, 1 in Rhizophagus, 1 in Sclerocystis and 1 in Paraglomus, among which Claroideoglomus etunicatum and Acaulospora mellea were dominant. At the high phosphate level of (87.7±8.0) mg/kg, AM fungi still formed arbuscules and vesicles. However, when the phosphate level reached (99.7±1.2) mg/kg, total colonization frequency and arbuscular abundance were significantly decreased in mycorrhizal roots, but vesicles were still be formed. [Conclusion] In this study, 25 AM fungi belonging to 7 genera that might be resistant to high phosphate concentration were identified from root-zone soils containing (88.2±17.6) mg/kg phosphate in cultivated land in Nansha district of Guangzhou city. The isolated strains such as C. etunicatum and A. mellea could be used as experimental strains in further studies on the high phosphate inhibition and the production of high-quality AM fungal inocula resistant to high phosphate.