DNA from the resistant and susceptible parents was
screened using 240 RAPD primers to identify RAPD
fragments linked to the resistance gene in the somaclone
SC09. Of the 240 primers, 203 produced amplification
products. During this survey we identified 48 RAPD primers
that differentiated resistant and susceptible parents, of
which eight were specific for the resistant parent and
resistant bulk, or for the susceptible parent and susceptible
bulk. Such primers were further used to screen the DNA of
seven different individual plants from each one of the
bulks. Of the eight primers that amplified RAPDs in a
bulk-specific manner, only one primer produced an
amplification band present in the resistant parent and
the resistant bulk, including all seven of the individuals
that constituted the resistant bulk. This band was not
observed in the susceptible parent or in the susceptible
bulk, including all seven individuals constituting the
susceptible bulk (Figure 2). This marker possessing
approximately 1200 base pairs (bp), was generated by primer
OPC02 ('GTGAGGC GTC'). Based on the co-segregation
analysis of 126 F2 plants, the marker OPC02 (1200) was mapped
at 1.7 cM of the resistance gene Pi-ar