Fig. 2.

Cloning and characterization of Medicago BS1 gene. (A) Map-based cloning leads to identification of a deletion at the BS1 locus. Shown are introns (horizontal lines), exons (solid boxes), and 5′ and 3′ untranslated regions (open boxes) of the BS1 locus, and the deletion region delimited by vertical lines. (B) RT-PCR analysis shows lack of BS1 transcripts in the mtbs1-1 mutant, in contrast to WT (A17). The expression of an ACTIN gene is present in both WT and mtbs1-1, serving as an internal control. (C and D) BS1-GFP fusion protein is localized to the nucleus in tobacco leaf epidermal cells. Shown are a confocal image of a tobacco leaf transiently expressing 35S::BS1-GFP and an overlay with a Normaski image. (E and F) As a control, free GFP driven by the 35S promoter was localized to the cytoplasm. (G–J) RNA in situ hybridization shows that BS1 transcripts were detected in SAM and leaf primordia as early as P0 in vegetative shoot bud (G) and in developing petal (p), carpel (c) and ovule (o) during reproductive development (I). No signals were detected in neighboring tissue sections when a sense probe was used (H and J). (K). Amino acid sequence alignments of BS1 homologs from alfalfa (M. sativa), soybean (G. max), and L. japonicus with M. truncatula BS1. TIFY and CCT2 domains are underlined in red and blue, respectively.