Abundance and Diversity of Arbuscular Mycorrhizal Fungi in Calamanrostis angustifolia Wetlands of the Sanjiang Plain, China

摘要

Calamanrostis angustifolia is the major colonizing plant in the wetlands of the Sanjiang Plain in northeastern China. These wetlands have severely suffered from agricultural practices that resulted in lowered water tables. Hence, in this study, we compared the soil arbuscular mycorrhizal fungi (AMF) content from three types of C. angustifolia wetlands. Based on the water gradient, from high to low, the research site was categorized into marsh C. angustifolia wetland (W1), marsh meadow C. angustifolia wetland (W2) and meadow C. angustifolia wetland (W3). The fungal infection rate of C. angustifolia roots was investigated by microscopy. This showed presence of vesicles, arbuscules, infection sites and intra-and inter-cellular hyphae, from which we conclude this plant species is a typical arbuscular mycorrhizal host. Isolation of spores from the soil and morphological characterization revealed presence of at least 14 different AMF types, of which 10 could be identified at genus or species level. Total DNA was isolated from the three soil types and subjected to amplification and meta-genomic sequencing. This revealed the presence of fungal OTUs belonging to 2 orders, 7 families and 14 genera. Among the detected genera, Redeckera, Pacispora, Racocetra, Cetraspora, Dentiscutata, and Rhizophagus were detected for the first time in a wetland environment. The diversity index and an RDA analysis revealed that as the water content in the soil decreased, the soil nutrients and the pH increased. This resulted in a significant increase in the total amount and diversity of the AMF community in the intermediate W2 wetland. There was a significant difference in the community structure of W2 compared to W3 or W1. The reasons for this remain elusive but oxygen and nutrient levels may be partly responsible for the observations. This study provides scientific insights in the structural diversity and the spatial heterogeneity of the AMF community in various types of C. angustifolia.