| Arbuscular mycorrhizal fungi (AMF) form a symbiosis with plant roots in more than 80% of terrestrial plant species. AMF enhance plant nutrient absorption, increase soil stability and protect plants against soil pathogens. Twenty samples collected from 9 sites in the Stephen F. Austin Experimental Forest, Angelina National Forest and Sabine National Forest, Texas, USA were sequenced using the 454 FLX pyrosequencing and 18S generic primers. Each sample produced about 7000 reads in average, from which an exact number of operational taxonomic units (OTUs) present in the sample were determined. The sequence identity was determined by BLAST. AMF species from four genera were found in studied sites, Glomus (94.5%), Gigaspora (4.2%), Scutellospora (1.0%), and Paraglomus (0.3%). Twenty one distinct OTUs of AMF were found and relative percent abundance of AMF species ranged from 0.1 to 67%. Two matrices were constructed: a OTUs-by-samples matrix and an environmental matrix. Patterns of AMF abundance and richness were compared with patterns of soils and topography across the habitat types using univariate and multivariate analysis including non-metric multidimensional scaling and generalized additive modeling. It was shown that the AMF composition significantly correlates with soil moisture, landscape type, and nutrient soil elements, the most significant of which was potassium. Describing the diversity of AMF across several east Texas habitat types could help better understand the genetic organization and taxonomy of AMF and may enhance local forest management and agriculture. |
