Poster: Plant Pathogen/Symbiont Interactions
Abs #
754: A screen for identifying genes required for both plant development and formation of legume root nodules.
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Presenter: |
Harris, Jeanne M., jmharris@zoo.uvm.edu |
Authors | Harris, Jeanne M. (A) Mitchell, David (A) Liang, Yan (A) | | Affiliations: |
(A): University of Vermont
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The evolution of nitrogen-fixing legume nodules has long been a mystery. How did the development of an entire organ evolve so rapidly? There are two possibilities, which are not mutually exclusive: legumes either evolved new genes specific to nodule development or they recruited existing genes and pathways for this purpose. The observation that several plant hormones regulate nodule development suggests that the evolution of nodule development was accompanied by recruitment of at least some development genes and pathways to nodule formation.
In order to test this idea, we are screening a fast neutron-bombarded M2 population of the model legume Medicago truncatula for mutants with defects in early seedling development (from days 1-7). We then screen the progeny of these putative mutants for defects in nodulation. In this way we hope to identify genes with a dual function in plant development and nodulation, revealing genes and ultimately pathways that have been recruited from an original function to a new role in nodule development. A number of developmental mutants that are also defective in nodule development or regulation have been identified and we are in the process of characterizing them. Two mutants in particular have an interesting combination of phenotypes. One of these mutants, giraffe, has long hypocotyls, pale green leaves and precocious nodules. In contrast, eve mutants have long primary roots, short, sparse root hairs and an excessive number of nodules. Analysis of these mutants may provide a window into the intersection of pathways controlling both plant development and nodule formation. In this way, we hope to learn more about the way that legumes have altered their development to accommodate their bacterial partner.
