Figure 4.
Positional cloning of the BRX gene. (A) Schematic representation of recombination mapping of the BRX locus to an ∼45-kb interval on chromosome I of Arabidopsis. Solid bars indicate predicted genes, numbers indicate their unicode. (B) Summary of the genetic and sequence analysis of the genes in the region of interest. (n.a.) Not available; (n.d.) not determined. (C) Schematic presentation of the intron-exon structure of the BRX gene. Boxes represent exons, lines represent introns, and their sizes are given in nucleotides below. The shaded boxes indicate the open reading frame. The position of the mutation resulting in a premature stop codon in the Uk-1 accession is shown. (D) Representative Uk-1, Sav-0, and brxS seedlings and brxS seedlings carrying a 35S::BRX transgene, 9 dag grown in constant light on 0.5× MS medium containing 0.3% sucrose. (E) Number of cells in cortical cell files of the root meristematic and elongation zones as defined in the text, grown on 0.5× MS medium containing 2.0% sucrose and scored 6 dag. n ≥ 10. (F) Primary root length of seedlings grown in constant light on 0.5× MS medium containing 1.0% sucrose, 9 dag. n ≥ 15. (G) RT-PCR of BRX and the control gene actin4 (ACT4) from RNA isolated from different sources. Control reactions for BRX in which the reverse transcriptase was lacking (BRX-RT) are shown as well. (M) DNA size marker. (H) Primary root length of seedlings grown in constant light on 0.5× MS medium containing 1.0% sucrose, 7 dag. n ≥ 15. Error bars are standard error.