Hypothetical model of VRN2-mediated repression of growth in Arabidopsis. In the dividing cells of the hypoxic shoot meristem and emerging leaves, stable VRN2-PRC2 deposits H3K27me3 at core PIF4 target genes (e.g., HAT4/YUC9). (ii) In the expanding cells of normoxic leaf tissues, where VRN2 is degraded, this H3K27me3 mark is stable and facilitates the conditional repression of these genes by the red-light-activated phyB-VIL1 module. This restricts the expression of SAURs in the cell expansion zone in response to light. The green-to-yellow gradient follows the transition of division-mediated to expansion-mediated growth across developmental time as leaves emerge and grow.
