A linkage map of hexaploid oat based on grass anchor DNA clones and its relationship to other oat maps

A cultivated oat linkage map was developed using a recombinant inbred popul ation of 136 F-6:7 lines from the cross 'Ogle' x 'TAM O-301'. A total of 44 1 marker loci, including 355 restriction fragment length polymorphism (RFLP ) markers, 40 amplified fragment length polymorphisms (AFLPs), 22 random am plified polymorphic DNAs (RAPDs), 7 sequence-tagged sites (STSs), 1 simple sequence repeat (SSR), 12 isozyme loci, and 4 discrete morphological traits , was mapped. Fifteen loci remained unlinked, and 426 loci produced 34 link age groups (with 2-43 loci each) spanning 2049 cM of the oat genome (from 4 .2 to 174.0 cM per group). Comparisons with other Avena maps revealed 35 ge nome regions syntenic between hexaploid maps and 16-34 regions conserved be tween diploid and hexaploid maps. Those portions of hexaploid oat maps that could be compared were completely conserved. Considerable conservation of diploid genome regions on the hexaploid map also was observed (89-95%); how ever, at the whole-chromosome level, colinearity was much lower. Comparison s among linkage groups, both within and among Avena mapping populations, re vealed several putative homoeologous linkage group sets as well as some lin kage groups composed of segments from different homoeologous groups. The re lationships between many Avena linkage groups remain uncertain, however, du e to incomplete coverage by comparative markers and to complications introd uced by genomic duplications and rearrangements.