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. Author manuscript; available in PMC: 2017 Feb 1.
Published in final edited form as: Curr Opin Plant Biol. 2015 Nov 7;29:1–8. doi: 10.1016/j.pbi.2015.09.008

Figure 3. A model for guard cell fate stabilization.

Figure 3

The latest-acting bHLH transcription factor in the stomatal lineage, FAMA, acts in guard cells to bind the promoters of early stomatal lineage genes and to recruit RBR. Based on known interactions between RBR and PRC2 components in other systems, this could lead to establishment of localized deposition of H3K27me3 marks on promoters of stomatal lineage genes and limits to their transcription. When the interaction between FAMA and RBR is disrupted (as in the FAMA-LGK mutant) FAMA does not bring RBR to the early stomatal lineage promoters, PRC2 is not recruited, and early stomatal lineage genes are activated leading to re-capitulation of the entire lineage. The MYB transcription factor FLP may also be involved in this complex, though no functional evidence for it (nor for PRC2) being required for fixing GC fate is currently available and thus this putative components of the model are shown in white.