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. 2015 Jun 9;34(15):1992–2007. doi: 10.15252/embj.201490899

Figure 1.

Figure 1

Identification of R1R2R3-Myb proteins with a repressor function

  • A Phylogenetic analysis of R1R2R3-Myb proteins in plants. Protein names that begin with “Nt” are from tobacco, those that begin with “Os” are from rice, and MYB3R1–MYB3R5 are from Arabidopsis. Protein sequences within Myb domains were used to construct an unrooted phylogenetic tree.
  • B Schematic structures of the MYB3R3 and MYB3R5 genes. The insertion sites of the T-DNA in each mutant allele are indicated. Exons are indicated by boxes, where untranslated regions and protein coding regions are shown in white and black colors, respectively.
  • C Upregulation of G2/M-specific genes in the double myb3r3/5 and triple myb3r1/3/5 mutants. Transcript levels for a set of G2/M-specific genes were analyzed by qRT–PCR in wild-type (WT), myb3r3/5, and myb3r1/3/5 seedlings (10 DAG). Transcript level of histone H4 was also analyzed as a control. Expression levels of each transcript were normalized by the levels of ACT2 expression and are expressed as relative values with average levels of transcripts in all the plants analyzed being set to 1.0. Error bars represent standard deviation (SD) for n = 3.
  • D, E MYB3R1, MYB3R3, and MYB3R5 act redundantly in the repression of G2/M-expressed genes. A qRT–PCR analysis of EDE1 and CYCB1;1 showed that MYB3R1, but not MYB3R4, acts as a repressor that is redundant with MYB3R3 and MYB3R5 (D), and that MYB3R1, MYB3R3, and MYB3R5 act redundantly with different contributions for repression of the G2/M-specific genes (E). The qRT–PCR was performed using 10-day-old seedlings with the indicated genotypes, where plus indicates the wild-type form and minus indicates homozygous mutation for each MYB3R gene. Expression levels are expressed as relative values that were normalized to the levels of ACT2 expression. Error bars represent SD for n = 3.