Event Dates: March 14, 2014 - 4:00pm - 5:00pm
Tyler Wittkopp, Grossman Lab, Functional genomics to elucidate photosynthetic processes: Utilizing comparative genomics and insertional mutagenesis to identify novel GreenCut proteins involved in photosynthesis
Por Juthamas Sae-Seaw Abstract:
The balance between stem cell maintenance and differentiation is crucial for optimal growth of plant roots, yet the factors controlling this balance are unknown. Here, we demonstrate that a balance between antagonistic and spatially complementary actions of two phytohormones, brassinosteroid (BR) and auxin, is crucial for stem cell dynamics and optimal root growth. BR metabolism establishes a pattern of the BR-activated transcription factor BZR1 in the transition-elongation zone and inactive BZR1 in the stem cell niche, which contributes significantly to the developmental zone-specific transcriptomes and cellular behavior such as elongation and quiescence. Furthermore, in contrast to their known synergism in shoot development, BR and auxin show antagonistic and spatially complementary actions on gene expression and cell elongation, and auxin inactivates BZR1 specifically in the transition-elongation zone. Our study reveals BR-auxin antagonism as a major hormone circuit regulating root growth, demonstrating dramatic alteration of hormone relationships by developmental context in plants.
Tyler Wittkopp Abstract:
Identifying novel components of photosynthesis will improve our understanding of this vital process and afford us opportunities to engineer plants and algae for increased efficiency of solar energy utilization, higher agricultural yields and a greater resistance to adverse conditions associated with environmental change. The GreenCut is an inventory of nuclear-encoded proteins conserved among photosynthetic organisms belonging to the Green Lineage (Viridiplantae), but not present in heterotrophic (nonphotosynthetic) organisms. Many of the uncharacterized GreenCut proteins (unknown specific functions) are likely to have regulatory roles associated with the activity of photosynthetic processes (electron transport and carbon fixation) and the biogenesis of chloroplasts. By combining insertional mutagenesis of specific GreenCut genes with biochemical and biophysical analyses, using the model algal system Chlamydomonas reinhardtii, we are gaining new insights into photosynthesis and how it is finely tuned to a dynamic environment.