Crown rust, which is caused by Puccinia coronata f. sp. avenae, P. Syd. & Syd., is the most destructive disease of cultivated oats ( Avena sativa L.) throughout the world. Resistance to the disease that is based on a single gene is often short-lived because of the extremely great genetic diversity of P. coronata, which suggests that there is a need to develop oat cultivars with several resistance genes. This study aimed to identify amplified fragment length polymorphism AFLP markers that are linked to the major resistance gene, Pc68, and to amplify the F 6 genetic map from Pc68/5*Starter * UFRGS8. Seventy-eight markers with normal segregation were discovered and distributed in 12 linkage groups. The map covered 409.4 cM of the Avena sativa genome. Two AFLP markers were linked in repulsion to Pc68: U8PM22 and U8PM25, which flank the gene at 18.60 and 18.83 centiMorgans (cM), respectively. The marker U8PM25 is located in the linkage group 4_12 in the Kanota * Ogle reference oat population. These markers should be useful for transferring Pc68 to genotypes with good agronomic characteristics and for pyramiding crown rust resistance genes.
