Some transition metals (iron, copper, zinc, molybdenum,…) are essential nutrients for life. In plants they are involved in a plethora of processes, from photosynthesis to the immune response. In spite of their importance, there is a prevalent low metal bioavailability in most agricultural soils. This has a profound impact on crop production and human nutrition. Our research efforts are directed towards understanding how metal homeostasis is maintained in model legume Medicago truncatula. Legumes are one of the most important food and staple crops worldwide, the main vegetable protein source, and key elements in sustainable agriculture strategies due to their ability to fix atmospheric nitrogen in symbiosis with certain soil bacteria (rhizobia). This symbiotic nitrogen fixation requires relatively vast amounts of metals and, consequently, exerts a heavy toll on the host plant metal homeostasis. This is in part ameliorated by another endosymbiont, arbuscular mycorrhizal fungi, that improve nutrient uptake, including essential metal oligonutrients, when they are lacking in the surrounding soil. Consequently, within this framework of M. truncatula metal homeostasis, we are paying closer attention to the metal exchange mechanisms between this legume and its two main associated endosymbionts, rhizobia and arbuscular mycorrhizal fungi.