Nitrogen fixing legume species provide humans with a wide array of agricultural products and have been implemented as integral components of various farming regimes.   Such plants perform the feat of fixing atmospheric nitrogen by establishing a symbiotic relationship with specialized nitrogen fixing soil bacteria collectively known as Rhizobia.  Success of the symbiotic plant-rhizobia relationship depends not only on adequate delivery of usable nitrogen from the rhizobia to the host plant, but also on the supply of requisite nutrients from the plant to the bacteria.  Among the nutrients necessary for proper nodule function are metals such as Mg, Fe, Mn, and Zn, which are essential cofactors in various bacterial enzymes.  Little is known about how these metals are delivered to the bacteria, the concentrations required for proper nodule function, or how their supply affects nodule development.  Therefore, this study examines the influence of bioavailable rhizosphere zinc on root nodule formation and functions using a mutant of the model legume Medicago truncatula know as raz for “requires additional zinc”.  Confocal microscopy together with nucleic acid and metal specific dyes was used to monitor the development of raz and wild type (WT) M. truncatula plants grown together through a 21 day developmental time course.  Initial results indicate that raz had delayed nodule development and function compared to the M. truncatula WT plants.   Using a mutant strain of M. truncatula to explore the role of metals in nodule formation and function will create a foundation for interpreting the genetic basis for the mechanisms involved.  A greater understanding of these mechanisms could lead to the production of fortified crops for improved human and ruminant nutrition that require less N based fertilizers, and thus,  reduced input costs and/or nitrogenous pollution.