Figure 1.

Structure of functional and null RPM1 alleles in A. thaliana. (A) Schematic comparison of RPM1 and rpm1-null structure. The RPM1 locus in resistant and susceptible accessions is closely flanked by two ORFs. GTP and M4. In all susceptible accessions that have been examined, the RPM1 gene has been replaced by a 98-bp sequence of unknown origin. (B) Sequence of the null allele in susceptible Arabidopsis. The sequence of rpm1-null from Nd-0 is aligned with conserved regions that flank the 5′ and 3′ breakpoints of the replacement in Col-0. Conserved nucleotides are capitalized, and the 98-bp filler is emphasized by italics. A direct repeat in Col-0 at the 3′ breakpoint with Nd-0 is underlined.