Basic Pentacysteine Proteins Repress Abscisic Acid Insensitive4 Expression via Direct Recruitment of the Polycomb-Repressive Complex 2 in Arabidopsis Root Development

Abstract

Plant transcription factors generally act in complex regulatory networks that function at multiple levels to govern plant developmental programs. Dissection of the interconnections among different classes of transcription factors can elucidate these regulatory networks and thus improve our understanding of plant development. Here, we investigated the molecular and functional relationships of the transcription factors ABSCISIC ACID INSENSITIVE 4 (ABI4) and members of the BASIC PENTACYSTEINE (BPC) family in lateral root (LR) development of Arabidopsis thaliana. Genetic analysis showed that BPCs promote LR development by repressing ABI4 expression. Molecular analysis showed that BPCs bind to the ABI4 promoter and repress ABI4 transcription in roots. BPCs directly recruit the Polycomb Repressive Complex 2 (PRC2) to the ABI4 locus and epigenetically repress ABI4 expression by catalyzing the trimethylation of histone H3 at Lys27. In addition, BPCs and ABI4 co-ordinate their activities to fine-tune the levels of PIN-FORMED1, a component of the auxin signaling pathway, and thus modulate LR formation. These results establish a functional relationship between two universal and multiple-role transcription factors, and provide insight into the mechanisms of the transcriptional regulatory networks that affect Arabidopsis organogenesis.

Global Dynamic Molecular Profiles of Stomatal Lineage Cell Development by Single-Cell RNA Sequencing

“…BPC6 has been shown to participate in the regulation of ABI4 (Mu et al, 2017), and subcellular localization indicated that BPC6-GFP is in the nucleus of guard cells (Figure 7A). To detect whether BPCs can directly regulate the expression of key marker genes of stomatal development, we analyzed the transcript levels of both SCRM and SCRM2 , which can form a complex to regulate the functions of SPCH, MUTE, and FAMA (Pillitteri and Torii, 2012).…”

“…Expression of BPC genes occurs widely, but to different extents, in various organs. These genes play important roles in regulating the vegetative and reproductive development (Kooiker et al, 2005; Monfared et al, 2011; Simonini et al, 2012; Simonini and Kater, 2014; Mu et al, 2017; Shanks et al, 2018). Our results indicate that besides the core TFs (e.g.…”

Role of BASIC PENTACYSTEINE transcription factors in a subset of cytokinin signaling responses

“…In this model (Figure 8), the BPCs, type-B ARRs and CRFs co-regulate gene expression by either independently binding to different cis-acting elements to convergently regulate target gene expression or by binding to elements as part of the same transcriptional complex. The BPCs may also recruit other complexes to these genes such as the PRC chromatin modifiers to promote or repress transcription of target genes (Hecker et al, 2015;Mu et al, 2017;Xiao et al, 2017).…”

“…The BPCs interact with Polycomb-Repressive Complex 1 (PRC1) proteins, which form protein complexes that remodel chromatin by modifying histone tails to repress transcription of genes (Mu et al, 2017;Xiao et al, 2017). Furthermore, BPC6, a class II BPC, interacts with a member of the PRC1 complex, LIKE HETEROCHROMATIN 1 (LHP1) and recruits LHP1 to GAGA binding motifs and the PRC2 member Vernalization 2 (VRN2) was shown to associate with BPC6 via LHP1 in vivo (Hecker et al, 2015).…”

“…For example, the bpc1,2,4,6 mutant has an altered response to ethylene, though it is unaffected in the response to auxin and gibberellic acid (Monfared et al, 2011). BPCs also regulate abscisic acid signaling by regulating transcription of ABI4 (Mu et al, 2017). Although BPCs are linked to ethylene and abscisic acid (ABA) signaling, not all of the phenotype observed in the bpc1,2,4,6 mutant can be attributed to alterations in the function of these hormones and thus, the BPCs may regulate multiple hormonal pathways (Monfared et al, 2011).…”