The Glomeromycota are the arbuscular mycorrhizal fungi (AMF), which form dependent, internal, symbiotic unions with plants.
An arbuscular mycorrhiza is formed when the fungus penetrates the cortical root cells of vascular plants and forms specialized structures called arbuscules, which form sites for exchange of important nutrients such as phosphorous, carbon and water. The plant supplies the AMF with carbon in the form of hexoses derived from photosynthesis; in turn, the AMF provide the plant with increased phosphorous uptake and transfer to the plant.
The presence of AMF is thought to benefit the plant mainly through increased phosphorous uptake; the fungus has greater surface contact with soil and can translocate up to 6x more phosphorous than plant roots; furthermore, the AMF symbiont actively solubilizes phosphorous precipitates by selective uptake of NH4+ and release of H+ which lowers the pH thus making more phosphorous bioavailable.
The ubiquitous relationship between land plants and AMF is an ancient 460 million year old symbiosis, and is thought to have facilitated the evolutionary-transition of plants from sea to land.
Image courtesy of Schenck & Smith emend. Walker & Vestb. taken from Agriculture and Agri-Food Canada website www.agr.gc.ca
Image courtesy of Nicolson & Schenck. Taken from Agriculture and Agri-Food Canada website www.agr.gc.ca
Image courtesy of Schenck & Smith Melzer. Taken from Agriculture and Agri-Food Canada website www.agr.gc.ca
Image courtesy of McGee. Taken from Agriculture and Agri-Food Canada website www.agr.gc.ca