BIN2 Functions Redundantly with Other Arabidopsis GSK3-Like Kinases to Regulate Brassinosteroid Signaling

Zhenyan Yan, Jun Zhao, Peng Peng, Ray K. Chihara, Jianming Li*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

176 Citations (Scopus)


GLYCOGEN SYNTHASE KINASE3 (GSK3) is a highly conserved serine/threonine kinase involved in a variety of developmental signaling processes. The Arabidopsis (Arabidopsis thaliana) genome encodes 10 GSK3-like kinases that are clustered into four groups. Forward genetic screens have so far uncovered eight mutants, all of which carry gain-of-function mutations in BRASSINOSTEROID-INSENSITIVE2 (BIN2), one of the three members in group II. Genetic and biochemical studies have implicated a negative regulatory role for BIN2 in brassinosteroid (BR) signaling. Here, we report the identification of eight ethyl methanesulfonate-mutagenized loss-of-function bin2 alleles and one T-DNA insertional mutation each for BIN2 and its two closest homologs, BIN2-Like1 and BIN2-Like2. Our genetic, biochemical, and physiological assays revealed that despite functional redundancy, BIN2 plays a dominant role among the three group II members in regulating BR signaling. Surprisingly, the bin2bil1bil2 triple T-DNA insertional mutant still responds to BR and accumulates a more phosphorylated form of a BIN2 substrate than the wild-type plant. Using the specific GSK3 inhibitor lithium chloride, we have provided strong circumstantial evidence for the involvement of other Arabidopsis GSK3-like kinases in BR signaling. Interestingly, lithium chloride treatment was able to suppress the gain-of-function bin2-1 mutation but had a much weaker effect on a strong BR receptor mutant, suggesting the presence of a BIN2-independent regulatory step downstream of BR receptor activation.
Original languageEnglish
Pages (from-to)710-721
Number of pages12
JournalPlant Physiology
Issue number2
Early online date29 Apr 2009
Publication statusPublished - Jun 2009

Scopus Subject Areas

  • Physiology
  • Genetics
  • Plant Science


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