File:RSS3 Encodes a Nuclear Protein Homologous to the Regulatory Domains of RB-Like bHLH Proteins.jpg

(A) Map-based cloning of RSS3 (top) and the schematic representation of the RSS3 gene structure (bottom). The rss3 locus was delimited between the indicated markers. The chromosomal position of the markers and the number of F2 lines exhibiting the rss3 phenotype among 1501 lines examined are provided in brackets and parentheses, respectively. Exons (closed boxes), 5′- or 3′-untranslated regions (open boxes), and the position of the first codon (ATG), stop codon (TAG), and 47-bp deletion in rss3 are indicated.

(B) Schematic structure of RSS3 and an R/B-like bHLH protein, MYC2, of Arabidopsis. The regions conserved between RSS3 and At-MYC2 (I to IV) and the position of the 21–amino acid (a.a.) deletion in rss3 are shown. bHLH represents the basic helix-loop-helix DNA binding domain.

(C) The amino acid sequences of the N-terminal region of RSS3, RSS3-related proteins, and R/B-like bHLH factors were aligned using the MAFFT program. The red dotted line represents the sequence lacking in rss3. The conserved regions (I to IV) and JAZ interacting domain of At-MYC2 and At-MYC3 (Fernández-Calvo et al., 2011) are indicated.

(D) GFP signals of rice roots carrying RSS3-EGFP driven by the RSS3 promoter or EGFP driven by the Actin promoter. The red arrowhead indicates the border between the MZ and EZ. Magnified views of the MZ (top) and EZ (bottom) are shown in the right panels. Bars = 200 μm (left) and 10 μm (right panels).