Dissertation Research: Diversity, Specificity, and Dynamics of Rhizobia-legumes Associations in Canyons of the Sonoran Desert

University Of Arizona, Tucson AZ

Investigators

Abstract

PROJECT SUMMARY Recently, there has been growing interest in legume-rhizobia associations as model systems for studying mutualisms, but a central obstacle is that little is known about the genetic structure of native communities. We know that associations can be specific or promiscuous, but very few studies have described spatial or temporal variation in native rhizobia-legume communities. We intent to examine levels of spatial and temporal variation in communities of rhizobia and legumes in natural environments. We will compare associations at various geographic scales, from within nodules to between canyons. We will measure how associations change over time, considering variation between months, seasons, and years. By considering specificity of associations and the genetic structure of a native community, our goal is to better understand the potential for coevolution to shape this mutualism. The proposed work uses sequences from 1329 strains from 15 plant species to characterize the effect of plant taxa, microhabitat differences, and seasonal differences on rhizobial genetic variation and specificity of associations. We will contribute to the understanding of this imporant mutualism by seeking to describe natural systems in detail, characterizing rhizobial genetic diversity, and measuring the extent that specialization and generalization is achieved in naturally evolving populations.