MtCOPT2 is a mycorrhiza-specific copper transporter

Arbuscular mycorrhiza are endosymbiotic relationships established between a specific group of fungi (Glomeromycota) and 85% of terrestrial plants. This symbiosis provides plants with higher tolerance to biotic and abiotic stresses, as well as enhanced nutrition. Through the fungal hyphae, host plants may obtain 90% of the phosphate that requires, 50% of nitrogen, and similar amounts of other nutrients At the arbuscules, multibranched hyphae that create a complex interface with host cell plasma membranes, nutrients are exchanged. Myycorrhiza-specific plant phosphate and ammonium transporters have been identified. They are located at the arbuscule interface, and mediate the uptake of phosphorus and ammonia by the plant cells. However, there is no evidence until now of mycorrhiza-specific processes for transition metal uptake.

The CBGP group "Metal Homeostasis in Plant-Microbe Interactions", in collaboration with researchers at EEZ-CSIC and ICA-CSIC, has identified the first mycorrhiza-specific transition metal transporter. MtCOPT2 is a copper transporter located in the in the plasma membrane, expressed in cells that contain arbuscules. These data are consistent with a role of MtCOPT2 in plant copper uptake at the arbuscule interface. In addition, MtCOPT2 is very similar to MtCOPT1, a copper transporter specific of the legume-rhizobia symbiosis. This highlights the evolutionary relationship of metal homeostasis mechanisms in both symbioses.