Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 25, 1995
Publication Date: N/A
Interpretive Summary: Comparative mapping of genomes illustrates a broad range of conservation of gene order along chromosomes of related species. However, research in this area only has just begun to address agronomically important genes. Genes for host plant resistance are involved in recognition of invading pathogens and activation of defense systems. They have been used in crop breeding programs because of their effectiveness in preventing disease and ease of handling as simply inherited traits. To determine the relationships of these genes among cereal crops, the colinearity of molecular markers linked with resistance genes were determined for related chromosomes of oats, barley, and maize. Generally, as in other comparative mapping studies, there was coalignment of molecular markers and resistance genes on small chromosomal fragments among these linkage groups. This provides a foundation to explore the relationships of these resistance genes in future research. Knowledge of these relationships will benefit plant pathologists and geneticists investigating new methods to control diseases.
Technical Abstract: The colinearity of markers linked with resistance genes on linkage group A of diploid oat, the homoeologous groups in hexaploid oat, barley chromosome 1H and homoeologous maize chromosomes were determined. Thirty-two probes from homoeologous group 1 chromosomes of the Gramineae were tested. Most of the heterologous probes detected polymorphisms which mapped to linkage group A of diploid oat, two linkage groups of hexaploid oat, barley chromosome 1H, and maize chromosomes 3, 6, and 8. Many of these DNA markers appeared to have conserved linkage relationships with resistance and prolamin genes in Avena, Hordeum, and Zea mays. These resistance genes included the Pca crown rust resistance gene cluster in diploid oat, the R203 crown rust resistance gene in hexaploid oat, the Mla powdery mildew resistance gene cluster in barley, and the rp3, wsm1, wsm2, mdm1, ht2, and htn1 resistance genes in maize. Prolamin genes included Avn in diploid oat and Hor1 and Hor2 in barley. A high degree of colinearity was revealed among the common RFLP markers on the small chromosomal fragments among these homoeologous groups.