Figure 3.

Location and structure of functional and null RPM1 loci in B. napus. (A) Schematic representation of the amphidiploid B. napus genome indicating the loci hybridizing to the Arabidopsis RPM1, M4, and GTP clones. Linkage groups N1 to N10 and N11 to N19 represent the A and C genomes, respectively. Hatched and filled areas of the arrows indicate regions of primary homeology between the A and C genomes. Unfilled areas represent regions for which primary homeology between the genomes has yet to be detected. (B) Schematic representation of RPM1 and rpm1-null loci, based on restriction mapping of phage clones. The locus names are listed on the left and the chromosomes to which they map are listed to the right. 1A and 9N contain RPM1, and the other three phage are rpm1-null. Ticks indicate either XhoI or XbaI restriction enzyme sites. The GTP, RPM1, and M4 genes are indicated above the figure. Equivalently shaded regions crosshybridize. Unshaded regions were not tested. (C) Sequence alignment at the 5′ breakpoint of sequence homology between B. napus RPM1 and rpm1-null. The 3′ ends of the GTP coding sequence are italicized, with stop codons emphasized in bold. Dashes represent gaps, and stars indicate sites that are identical among all five sequences. The arrow indicates the position at which similarity between the RPM1 and rpm1-null loci breaks down completely.