An anchored AFLP- and retrotransposon-based map of diploid Avena

A saturated genetic map of diploid oat was constructed based on a recombina nt inbred (RI) population developed from a cross between Avena strigosa (Ce ral Introduction, C.I. 3815) and A. wiestii (C.I. 1994). This 513-locus map includes 372 AFLP (amplified fragment length polymorphism) and 78 S-SAP (s equence-specific-amplification polymorphism) markers, 6 crown-rust resistan ce loci, 8 resistance-gene analogs (RGAs), one morphological marker, one RA PD (random amplified polymorphic DNA) marker, and is anchored by 45 grass-g enome RFLP (restriction fragment length polymorphism) markers. This new A. strigosa X A. wiestii RI map is colinear with a diploid Avena map from an A . atlantica X A. hirtula F-2 population. However, some linkage blocks were rearranged as compared to the RFLP map derived from the progenitor A. strig osa X A. wiestii F-2 population. Mapping of Bare-1-like sequences via seque nce-specific AFLP indicated that related retrotransposons had considerable heterogeneity and widespread distribution in the diploid Avena genome. Nove l amplified fragments detected in the RI population suggested that some of these retrotransposon-like sequences are active in diploid Avena. Three mar kers closely linked to the Pca crown-rust resistance cluster were identifie d via AFLP-based bulk-segregant analysis. The derived STS (sequence-tagged- site) marker, Agx4, cosegregates with Pc85, the gene that provides resistan ce specificity to crown-rust isolate 202 at the end of the cluster. This fr amework map will be useful in gene cloning, genetic mapping of qualitative genes, and positioning QTL (quantitative trait loci) of agricultural import ance.