Figure 1. SCAR marker screening of DNA from selected F2 segregants of RL6082/Thatcher cross. RR, homozygous resistant, Rr, heterozygous resistant, rr, susceptible. Far left and right lanes show a 100 base pair marker (BRL Life Technologies). Amplified DNA is resolved by agarose gel (1.4%) electrophoresis and ethidium bromide staining. The fragment of 900 base pairs (bp), indicated by the arrow, was found only in individuals homozygous (RR) or heterozygous (Rr) for the Sr39 resistance gene.