University of Kentucky
STUDY 2: The Influence of Soil Metal Concentrations on Root Nodule Formation and Function
Institution
University of Kentucky
Faculty Advisor/ Mentor
Hirotada Fukushige; David Hildebrand; David McNear
Abstract
Nitrogen fixing legume species have been implemented as integral components of various farming regimes worldwide. Such plants perform the feat of fixing atmospheric nitrogen by developing a root nodule and facilitating a symbiotic relationship with specialized nitrogen fixing soil bacteria collectively known as Rhizobia. 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 examined 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 in conjunction with nucleic acid specific dyes was used to monitor the development of raz and wild type (WT) M. truncatula plants through a 28 day developmental time course. Suboptimal levels of Zn (0.7M) for raz growth impede proper nodule function as is indicated by the retardation of nodule development compared to the M. truncatula WT plants. Using a mutant strain of the plant to explore the role of metals in nodule formation and function will help create a foundation for comprehending the genetic basis of the mechanisms involved. The biotechnological application of this knowledge could lead to the production of Zn fortified crops that require less N based fertilizer, which implies reduced input costs and the reduction of nitrogenous pollution.
STUDY 2: The Influence of Soil Metal Concentrations on Root Nodule Formation and Function
Nitrogen fixing legume species have been implemented as integral components of various farming regimes worldwide. Such plants perform the feat of fixing atmospheric nitrogen by developing a root nodule and facilitating a symbiotic relationship with specialized nitrogen fixing soil bacteria collectively known as Rhizobia. 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 examined 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 in conjunction with nucleic acid specific dyes was used to monitor the development of raz and wild type (WT) M. truncatula plants through a 28 day developmental time course. Suboptimal levels of Zn (0.7M) for raz growth impede proper nodule function as is indicated by the retardation of nodule development compared to the M. truncatula WT plants. Using a mutant strain of the plant to explore the role of metals in nodule formation and function will help create a foundation for comprehending the genetic basis of the mechanisms involved. The biotechnological application of this knowledge could lead to the production of Zn fortified crops that require less N based fertilizer, which implies reduced input costs and the reduction of nitrogenous pollution.