Glomus aggregatum

In 1939, Edwin John Butler described a Glomus aggregatum-like organism, but a name was not assigned to this species until 1943, when C.O. Rosendahl provided further details and named the species Rhizophagites butleri Rosendahl.^[3] Rosendahl wrote of his discovery of grouped (or clustered) sporangia on thick-walled, branched hyphae recovered from disturbed soils in Minnesota.^[4] Over the course of the next 40 years, various researchers were able to isolate similar fungal spores (typically in areas with sand based soils), but it wasn't until 1982 that G. aggregatum was first described. N.C. Schenck and George S. Smith were the researchers who made this discovery (in Florida Citrus groves) and their description was very similar to that of R. butleri and other fungi in the Glomus fasciculatum complex, however, it was still thought to be a different species than R. butleri.^[5] Further research was conducted, and after comparing extensive amounts of fungal spores, a conclusion was reached that G. aggregatum and R. butleri are in-fact the same species of fungi.^[3] Analyses by Schwarzott, Walker, and Schußler showed the genus was not monophyletic.^[6] The recent reorganization of the Glomeromycota phylogeny has renamed this species Rhizophagus aggregatum. ^[7]

The large scale application of arbuscular mycorrhizal fungi such as G. aggregatum  to human activities is its presence in commercial agriculture as an inoculum. Mycorrhizal relationships are important in this context because long-term agriculture tends to drain nutrients like phosphorus from the soil. For this reason, modern agriculture must apply vast amounts of phosphorus and other nutrients to fields yearly. Artificial and stimulated mycorrhizal associations can help plants mobilize phosphorus from the soil and utilize it.^[8] This can lead to higher yields and can also lessen the need for artificial phosphorus fertilization. It has also been suggested that selective inoculation of mycorrhiza into certain crops can increase water retention and help mitigate toxic factors in major food sources such as rice.^[9]

G. aggregatum and other members of Glomeromycota may also help in soil detoxification processes and ecosystem-level metabolic pathways. For example, an experiment in 2010 showed that root-mycorrhizal interface was significantly more successful at detoxifying arsenic-laced soils than non-associated roots. The study showed that the presence of G. aggregatum methylated the arsenic in the soil, but that indigenous soil microorganisms were responsible for further detoxification of dimethylarsinic acid into trimethylarsine oxide.^[10]