Reclamation negatively influences arbuscular mycorrhizal fungal community structure and diversity in coastal saline-alkaline land in Eastern China as revealed by Illumina sequencing

Arbuscular mycorrhizal (AM) fungi play a vital role in the succession of the plant community, as well as the enhancement of nutrient uptake and stress tolerance in their host plants. To obtain a better understanding of changes in the AM fungal community composition and diversity in response to reclamation with vegetation successions, Illumina sequencing was performed with samples that were collected from the coastal saline-alkaline fields of Eastern China. This study consisted of 3 reclamation stages consisting of 2 years (since 2011), 6 years (since 2007), and 34 years (since 1979) in combination with 4 vegetation statuses, namely bare land, seepweed (Suaeda salsa), couch grass (Imperata cylindrical), and corn (Zea mays). A total of 742 OTUs (Operational Taxonomic Units) from 20,474 sequences affiliated with 4 Glomeromycota families were obtained, with Glomeraceae and Glomus being the most abundant family and genus, respectively. Gigasporaceae, the second-most dominant family, primarily inhabited bare land at the early reclamation stage (2–6 years). With vegetation successions, there were decreasing trends for both Acaulosporaceae and Gigasporaceae and an increasing trend in Glomeraceae, along with a decreasing trend in soil electrical conductivity (EC) and an increasing trend in soil NO3−-N content. The diversity indices of Shannon (H'), abundance (ChaoI) and dominance (D) for AM fungi also decreased with decreasing soil EC or increasing soil NO3−-N content, and the Alatalo evenness index (Ea) of AM fungi increased, and it was inversely correlated with soil pH. Our results clearly showed changes in community structure and decreases in diversity indices for soil AM fungi in coastal saline-alkaline lands during the past 30 years of reclamations.