Effects of long-term fertilization on AM fungal community structure and Glomalin-related soil protein in the Loess Plateau of China

Arbuscular mycorrhizal fungi (AMF) are crucial for ecosystem functioning, and thus have potential use for sustainable agriculture. In this study, we investigated the impact of organic and mineral fertilizers on the AMF community composition and content of Glomalin-related soil protein (GRSP) in a field experimental station which was established in 1979, in the Loess Plateau of China. Roots and soils were sampled three times during the growing period of winter wheat in 2008. The treatments including: N (inorganic N), NP (inorganic N and P), SNP (straw, inorganic N and P), M (farmyard manure), MNP (farmyard manure, inorganic N and P), and CK (no fertilization). AMF communities of root and soil samples were analyzed using PCR-DGGE, cloning and sequencing techniques; and GRSP content was determined by Bradford assay. Our results indicated that spore density, GRSP, and AMF community varied significantly in soils of long-term fertilization plots at three different wheat growing stages. The effects of wheat growing period on AMF community in roots were much more evident than fertilization regimes. However, the diversity of AMF was low in our study field. Up to five AMF phylotypes appeared in each sample, with the overwhelming dominance of a Glomus-like phylotype affiliated to G. mosseae. GRSP content was correlated positively with organic carbon, total phosphorus, available phosphorus, soil pH, and spore densities, but correlated negatively with soil C/N (P?