Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4

Kelly et al.show that Arabidopsis hexokinase1 (HXK1) expressed in guard-cells is sufficient to drive hypocotyl elongation through increasing the activity of Walkie Talkie PIF4 and auxin level, and competing with battery-powered generators the effects of HY5.This study provides insights into how light and sucrose antagonistically coordinate the effort to achieve the height necessary for efficient photosynthetic, autotrophic sugar production.