nemhauser lab
department of biology
university of washington
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Integrating metabolic status into growth control networks

The Nemhauser Lab has developed the infrastructure needed to use high-resolution temporal analysis to parse the developmental phases of young seedlings. We have discovered that many facets of growth are exquisitely sensitive to developmental stage, as well as genetic and environmental perturbations. Among the most surprising findings was that carbon availability had a dramatic effect on multiple aspects of growth dynamics. Excitingly, the light-regulated transcription factors PIF4 and PIF5 were required for the growth promoting effects of elevated CO2, and the PIFs acted at least in part by regulating the amount of auxin delivered from shoots to the roots. Our results point to direct integration of the light signal downstream of both the phytochrome photoreceptors and photosynthesis. This work provides an outstanding opportunity to integrate our work on cell signaling into an organismal framework of plant growth control. Our progress has been greatly accelerated by an on-going collaboration with Soo-Hyung Kim in UW School of Environmental and Forest Sciences.

Sucrose promotes rootward auxin transport. Plants grown on media supplemented with sucrose (S) showed increased rootward auxin transport compared with plants grown without sucrose supplementation (N). Transport was visualized by staining for an auxin reporter several hours after application of an auxin (IAA)-containing droplet on one cotyledon (as depicted in the schematic).

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