AUTHOR=Diao Yangyang , Zhan Jingjing , Zhao Yanyan , Liu Lisen , Liu Peipei , Wei Xi , Ding Yanpeng , Sajjad Muhammad , Hu Wei , Wang Peng , Ge Xiaoyang 

TITLE=GhTIE1 Regulates Branching Through Modulating the Transcriptional Activity of TCPs in Cotton and Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01348

DOI=10.3389/fpls.2019.01348

ISSN=1664-462X

ABSTRACT=<p>Transcription factors (TFs) and transcriptional regulators are important switches in transcriptional networks. In recent years, the transcriptional regulator TIE1 (TCP interactor containing EAR motif protein 1) was identified as a nuclear transcriptional repressor which regulates leaf development and controls branch development. However, the function and regulatory network of <italic>GhTIE1</italic> has not been studied in cotton. Here, we demonstrated that <italic>GhTIE1</italic> is functionally conserved in controlling shoot branching in cotton and <italic>Arabidopsis</italic>. Overexpression of <italic>GhTIE1</italic> in <italic>Arabidopsis</italic> leads to higher bud vigor and more branches, while silencing <italic>GhTIE1</italic> in cotton reduced bud activity and increased branching inhibition. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that GhTIE1 directly interacted with subclass II TCPs (GhBRC1, GhBRC2, and GhTCP13) <italic>in vivo</italic> and <italic>in vitro</italic>. Overexpression of <italic>GhBRC1</italic>, <italic>GhBRC2</italic>, and <italic>GhTCP13</italic> in mutant <italic>brc1</italic>-2 partially rescued the mutant phenotype and decreased the number of branches, showing that these TCPs are functionally redundant in controlling branching. A transient dual-luciferase reporter assay indicated that GhTIE1 repressed the protein activity of GhBRC1 and GhTCP13, and thereby decreased the expression of their target gene <italic>GhHB21</italic>. Gene expression level analysis in <italic>GhTIE1</italic>-overexpressed and silenced plants also proved that <italic>GhTIE1</italic> regulated shoot branching <italic>via</italic> repressing the activity of <italic>BRC1</italic>, <italic>HB21</italic>, <italic>HB40</italic>, and <italic>HB53</italic>. Our data reveals that shoot branching can be controlled <italic>via</italic> modulation of the activity of the <italic>TIE1</italic> and <italic>TCP</italic> proteins and provides a theoretical basis for cultivating cotton varieties with ideal plant types.</p>