Auxins and the environment – Environmental and developmental regulation of auxin metabolism (with Gary Gardner)

USDA NIFA/2005-35318-16197 Roles for Multiple Auxin Biosynthetic Pathways 

Auxins function as key regulators at the intersection between developmental and environmental events and the response pathways that they trigger.  Auxin levels vary dramatically spatially within the plant and temporally throughout the life cycle of the plant, forming complex gradients that appear to be a central component of the hormone’s regulatory activity.  Accordingly, plants have evolved intricate networks to regulate auxin levels in specific tissues in response to changing environmental and developmental conditions. The proposed research will:

  1. Determine when specific tissues of maize and tomato seedlings become heterotrophic for auxin production.  This will be measured with plants grown under different environmental conditions and by determining the biosynthesis, conjugation and oxidation pathways that are invoked by light, temperature, and stress conditions
  2. Characterize the relationship between specific metabolic activities leading to free auxin production and the movement of auxin by the polar auxin transport system in different tissues in seedlings and mature plants.
  3. Determine specifically which tissues serve as a source for auxin that is moved to other tissues, using point application of stable isotope labeled precursors and measurement of the movement of the precursors, their metabolites, and the auxin produced from them. This work will link our expanding knowledge of auxin action to the dynamic and spatial aspects of hormone production. This proposal addresses Priority 2 of the Plant Biology (D) Growth and Development Program:  Hormonal regulation of growth and development, including studies of “cross talk” between different hormones or between hormones and other signals.