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Arbuscular mycorrhizal symbiosis is an important plant root-fungal partnership/interaction that affects the growth response of crops. We have investigated the molecular diversity of arbuscular mycorrhizal fungi (AMF) colonizing cowpea roots and the associated rhizosphere soil to test the hypothesis that community diversity in rhizosphere soil is similar to that in cowpea (Vigna unguiculata) roots. Cowpea plants were grown in farmers' fields located in seven agro-ecological zones of Benin, and soil and root samples were collected. The molecular diversity of the AMF in these samples was assessed after amplification of the large ribosomal subunit of DNA extracted from the soil and the root samples. At fruition, the frequency of mycorrhizal infection was unaffected by the agro-ecological zone, but there were significant differences in the intensity of AMF colonization among the zones. Multiple regression analysis showed that the main factor affecting mycorrhizal frequency at flowering was available phosphorus. Phylogenetic analysis revealed 25 operational taxonomic units belonging to two fungal families (Glomeraceae and Gigasporaceae). The diversity of AMF colonizing roots of cowpea in Benin was high and fairly similar to that in the rhizosphere soil but with a prevalence of the Glomeraceae. Despite the absence of strict host specificity in mycorrhizal symbiosis, there was a preferential association between some AMF species and cowpea cultivar IT96D-610.

Fungus-growing termites cultivate their mutualistic basidiomycete Termitomyces species on a substrate called a fungal comb. Here, the Suicide Polymerase Endonuclease Restriction (SuPER) method was adapted for the first time to a fungal study to determine the entire fungal community of fungal combs and to test whether fungi other than the symbiotic cultivar interact with termite hosts. Our molecular analyses show that although active combs are dominated by Termitomyces fungi isolated with direct Polymerase Endonuclease Restriction - Denaturing Gradient Gel Electrophoresis (PCR-DGGE), they can also harbor some filamentous fungi and yeasts only revealed by SuPER PCR-DGGE. This is the first molecular evidence of the presence of non-Termitomyces species in active combs. However, because there is no evidence for a species-specific relationship between these fungi and termites, they are mere transient guests with no specialization in the symbiosis. It is however surprising to notice that termite-associated Xylaria strains were not isolated from active combs even though they are frequently retrieved when nests are abandoned by termites. This finding highlights the implication of fungus-growing termites in the regulation of fungi occurring within the combs and also suggests that they might not have any particular evolutionary-based association with Xylaria species.