Arbuscular mycorrhizal fungi (AMF) communities associated with cowpea in two ecological site conditions in Senegal

The objective of this study was to characterize the diversity of arbuscular mycorrhizal fungal (AMF) communities colonizing the roots of Vigna unguiculata (L.) plants cultivated in two different sites in Senegal. Roots of cowpea plants and soil samples were collected from two fields (Ngothie and Diokoul) in the rural community of Dya (Senegal). Microscopic observations of the stained roots indicated a high colonization rate in roots from Ngothie site as compared to those from Diokoul site. The partial small subunit of ribosomal DNA genes was amplified from the genomic DNA extracted from these roots by polymerase chain reaction (PCR) with the universal primer NS31 and a fungal-specific primer AML2. Nucleotide sequence analysis revealed that 22 sequences from Ngothie site and only four sequences from Diokoul site were close to those of known arbuscular mycorrhizal fungi. Also, 47.6% of the clones from Ngothie site and 89.47% from Diokoul site were not close to known AMF. A total of 15 operational taxonomic units (OUT) were identified. Phylogenetic analyses showed that these clones belonged to the genera Glomus, Sclerocystis, Rhizophagus, Scutellospora, Gigaspora, Racocetra, Acaulospora and Redeckera. The genus Glomus is the most represented with six OTU, representing 40% of all OTU.