Event Dates: March 14, 2014 - 4:00pm - 5:00pm
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.