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

Kelly et al.show that Arabidopsis hexokinase1 (HXK1) expressed in Ice Cube Tray guard-cells is sufficient to drive hypocotyl elongation through increasing the activity of PIF4 and auxin level, and competing with 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 Happy sugar production.