Figure 10.

Proposed model for the role of BLI in regulating seed maturation and fatty acid biosynthesis. In WT and BLI-OE plants, WRI1 or other transcription factors recruit BLI to the promoter regions of WRI1 target genes or other WRI1-independent seed maturation genes. BLI may be required for the transcriptional activation of WRI1 or other TFs and affect their transcriptional activity by post-translational (e.g. phosphorylation) regulation. BLI affects chromatin by directly increasing H3K4me3 levels, decreasing H3K27me3 levels and nucleosome occupancy, or recruiting other proteins such as the SWI2/SNF2 complex and blocking PRC2 complex activity via a mutually exclusive interaction with CLF or SWI3B to help WRI1 or other TFs access and bind to the promoters of fatty acid biosynthesis or seed maturation genes. The H3K27me3 levels and nucleosome occupancy are enhanced at the promoters of fatty acid biosynthesis or other seed maturation genes in the bli loss-of-function mutant. This reduces the accessibility of AW-box cis-elements at the fatty acid biosynthesis genes or other cis-elements at the WRI1-independent seed maturation genes and reduces the binding of WRI1 or other TFs to the cis-elements. Black arrow indicates promotion; purple cross and black line indicates inhibition; thick blue arrow indicates high transcription; thin blue arrow indicates low transcription.