|Holland, Jim - Jim|
Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2000
Publication Date: N/A
Interpretive Summary: Genetic mapping in plants has proved an important tool for understanding gene function, for gene isolation, and for molecular approaches to plant breeding. Genetic maps of cultivated oat have had limited usefulness, however, because it has not been clear what the relationship between chromosomes and genetic linkage groups are. Part of the difficulty is that tcultivated oat has a complex genetic structure with the equivalent of thre complete genomes in each plant's nuclei. One approach to understanding the complex genome of oat is to first characterize the genome organization of a related wild oat species that has a similar but simpler genetic structure, with the equivalent of only one complete genome. We created a permanent mapping population of such a diploid oat population using molecular probes that have already been mapped in other grass species such as wheat, barley, rice, and corn. Use of such "standardized" probes allowed us to identify the chromosomal arrangements of this diploid oat and will help us to understand such arrangements in the cultivated oat.
Technical Abstract: A population of 100 F6-derived recombinant inbred lines was developed from the cross of two diploid (2n = 14) Avena accessions, CI3815 (A. Strigosa) and CI1994 (A. Wiestii). RFLP probes previously mapped in other grass species were used to develop a framework linkage map suitable for comparative genetics. Nine linkage groups were identified among the 181 loci mapped, with an average inter-locus distance of 5 cM, and a total genetic map length of 880 cM. A cluster of five tightly-linked crown rust resistance genes (Pca) was localized on the map, as were four loci identified by putative disease resistance gene from maize, sorghum, and wheat. None of the four loci identified by heterologous disease resistance probes were linked to the Pca locus. The linkage map was compared to previously published diploid and hexaploid linkage maps in an attempt to identify homologous or homoeologous chromosomes between populations. Locus sorders and linkage relationships were poorly conserved between the A. strigosa x A. wiestii map and other Avena maps. These results suggest that genetic duplications complicate such map comparisons within Avena or there is substantial chromosomal rearrangement between different species within Avena.