2. Academic Validation
  3. Involvement of BIG5 and BIG3 in BRI1 Trafficking Reveals Diverse Functions of BIG-subfamily ARF-GEFs in Plant Growth and Gravitropism

Involvement of BIG5 and BIG3 in BRI1 Trafficking Reveals Diverse Functions of BIG-subfamily ARF-GEFs in Plant Growth and Gravitropism

  • Int J Mol Sci. 2019 May 11;20(9):2339. doi: 10.3390/ijms20092339.
Shan Xue 1 2,  Junjie Zou 3,  Yangfan Liu 4 5,  Ming Wang 6 7,  Chunxia Zhang 8,  Jie Le 9
Affiliations

Affiliations

  • 1 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
  • 2 University of Chinese Academy of Sciences, Beijing 100049, China. [email protected].
  • 3 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
  • 4 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
  • 5 University of Chinese Academy of Sciences, Beijing 100049, China. [email protected].
  • 6 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
  • 7 University of Chinese Academy of Sciences, Beijing 100049, China. [email protected].
  • 8 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
  • 9 Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. [email protected].
PMID: 31083521 DOI: 10.3390/ijms20092339
Abstract

ADP-ribosylation factor-guanine nucleotide exchange factors (ARF-GEFs) act as key regulators of vesicle trafficking in all eukaryotes. In Arabidopsis, there are eight ARF-GEFs, including three members of the GBF1 subfamily and five members of the BIG subfamily. These ARF-GEFs have different subcellular localizations and regulate different trafficking pathways. Until now, the roles of these BIG-subfamily ARF-GEFs have not been fully revealed. Here, analysis of the BIGs expression patterns showed that BIG3 and BIG5 have similar expression patterns. big5-1 displayed a dwarf growth and big3-1 big5-1 double mutant showed more severe defects, indicating functional redundancy between BIG3 and BIG5. Moreover, both big5-1 and big3-1 big5-1 exhibited a reduced sensitivity to Brassinosteroid (BR) treatment. Brefeldin A (BFA)-induced BR receptor Brassinosteroid insensitive 1 (BRI1) aggregation was reduced in big5-1 mutant, indicating that the action of BIG5 is required for BRI1 recycling. Furthermore, BR-induced dephosphorylation of transcription factor BZR1 was decreased in big3-1 big5-1 double mutants. The introduction of the gain-of-function of BZR1 mutant BZR1-1D in big3-1 big5-1 mutants can partially rescue the big3-1 big5-1 growth defects. Our findings revealed that BIG5 functions redundantly with BIG3 in plant growth and gravitropism, and BIG5 participates in BR signal transduction pathway through regulating BRI1 trafficking.

Keywords

ARF protein; BIG family ARF-GEF; auxin; brassinosteroids; gravity response.

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