The TIE1 transcriptional repressor controls shoot branching by directly repressing BRANCHED1 in Arabidopsis

Abstract

Shoot branching is a major determinant of plant architecture and is regulated by both endogenous and environmental factors. BRANCHED1 (BRC1) is a central local regulator that integrates signals controlling shoot branching. So far, the regulation of BRC1 activity at the protein level is still largely unknown. In this study, we demonstrated that TIE1 (TCP interactor containing EAR motif protein 1), a repressor previously identified as an important factor in the control of leaf development, also regulates shoot branching by repressing BRC1 activity. TIE1 is predominantly expressed in young axillary buds. The gain-of-function mutant tie1-D produced more branches and the overexpression of TIE1 recapitulated the increased branching of tie1-D, while disruption of TIE1 resulted in lower bud activity and fewer branches. We also demonstrated that the TIE1 protein interacts with BRC1 in vitro and in vivo. Expression of BRC1 fused with the C-terminus of the TIE1 protein in wild type caused excessive branching similar to that observed in tie1-D and brc1 loss-of-function mutants. Transcriptome analyses revealed that TIE1 regulated about 30% of the BRC1-dependent genes, including the BRC1 direct targets HB21, HB40 and HB53. These results indicate that TIE1 acts as a positive regulator of shoot branching by directly repressing BRC1 activity. Thus, our results reveal that TIE1 is an important shoot branching regulator, and provide new insights in the post-transcriptional regulation of the TCP transcription factor BRC1.

Phytoplasma SAP11 effector destabilization of TCP transcription factors differentially impact development and defence of Arabidopsis versus maize

“…These binding specificities are supported by plant phenotypes; A. thaliana 35S::SAP11 MBSP and maize Ubi::FLAG-SAP11 MBSP lines phenocopy A. thaliana brc1 brc2 lines and maize tb1 lines, respectively. The A. thaliana 35S::SAP11 MBSP lines show stem proliferations, in agreement with A. thaliana BRC1 and BRC2 and maize TB1 (ZmTCP02) being suppressors of axillary bud growth [37, 49–51]. We also show that A. thaliana 35S::SAP11 MBSP and brc1 brc2 lines produce fully fertile flowers, whereas maize Ubi::FLAG-SAP11 MBSP plants produced only male tassels and no female inflorescences like maize tb1 plants [39,46].…”

“…PCFs promote cell proliferation, whereas CIN clade TCPs promote leaf and petal cell maturation and differentiation and have antagonistic roles to PCFs [30–33]. The ECE clade includes maize TEOSINTE BRANCHED 1 (TB1) and TB1 homologs of A. thaliana BRANCHED 1 (BRC1) and BRC2, that repress the development of axillary branches in plants [34–37], and CYCLOIDEA (CYC) that control flower symmetry [38]. TB1 and genes in the TB1 network have been targeted for selection during maize domestication from a teosinte ancestor [39,40].…”

CsBRC1 inhibits axillary bud outgrowth by directly repressing the auxin efflux carrier CsPIN3 in cucumber

“…Moreover, multiple regulatory pathways have been dissected for the TB1/BRC1-mediated suppression of shoot branching (5). The transcriptional repressor TIE1 (TCP interactor containing EAR motif protein 1) positively regulates shoot branching by directly repressing BRC1 activity in Arabidopsis, while the transcription factor IDEAL PLANT ARCHITECTURE1 (IPA1) promotes the expression of OsTB1 by directly binding to its promoter region in rice (29,30). BRC1 can directly bind to 3 homeodomain leucine zipper protein (HD-ZIP)-encoding genes, HOMEOBOX PROTEIN 21, HOMEOBOX PROTEIN 40, and HOMEOBOX PROTEIN 53, and positively regulates their expression in Arabidopsis.…”

Arabidopsis ERF4 and MYB52 Transcription Factors Play Antagonistic Roles in Regulating Homogalacturonan De-methylesterification in Seed Coat Mucilage

“…In eukaryotes, transcription factors usually work in combination which can promote or inhibit each other’s transcriptional activity in controlling expression of target genes. For example, the BRC1 transcriptional activity is suppressed by interaction with the transcriptional repressor TIE1 in Arabidopsis (Yang et al, 2018); the interaction between MdMYC2 and MdERF2 not only inhibits the binding of MdERF2 to MdACS1 , but also prevents MdMYC2 from binding to MdACS1 and MdACO1 in apple (Li et al, 2017); and during crown root elongation, the WOX11-ERF3 interaction either enhances WOX11-mediated repression or inhibits ERF3-mediated activation of RR2 in rice (Zhao et al, 2015). Here, we provided evidence for an interaction between ERF4 and MYB52 (Figure 4).…”