Fig. 3. Marker status of sugar beet plants rated for resistance or susceptibility to root-knot nematode. Amplified Nem06 marker DNA from 16 sugar beet plants either susceptible or resistant to root-knot nematode was digested with MseI and the products were separated by electrophoresis on a 5% (w/v) polyacrylamide gel. Arrows denote the migration of the marker allele (r) that is coupled with resistance and the marker allele (s) associated in repulsion with resistance. The 100-bp ladder was included as a size standard (lane M) with the sizes shown listed in kilobasepairs.