Submitted to: Genome
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/7/2003
Publication Date: 4/1/2003
Citation: Jessup, R.W., Burson, B.L., Burow, G., Wang, Y.W., Chang, C., Li, Z., Paterson, A.H., Hussey, M.A. 2003. Segmental allotetraploidy and allelic interactions in Buffelgrass (Pennisetum ciliare (L.) link syn. Cenchrus ciliaris L.) as revealed by genome mapping. Genome. 46:304-313. Interpretive Summary: Buffelgrass is an important pasture and range grass in arid and semi-arid sub-tropical regions throughout the world. The grass is very drought tolerant and produces large quantities of high quality forage with very little moisture; however, it has several traits that need improvement. Buffelgrass, like most warm-season grasses, is genetically complex and has a large number of chromosomes (polyploid). Because of this, little is known about the inheritance and genetic expression of these traits. The more that is known about the genetics of a trait, the better the chances are the trait can be improved through breeding. Therefore, in order to obtain a better understanding of the genetics of these traits, we used molecular tools and constructed a genetic map of buffelgrass. This is the first genetic map developed for any warm-season polyploid forage or turf grass. The map allows us to learn more about the genetics of the traits of interest and will help in improving the grass. Not only will this map help in improving buffelgrass but it will be useful in improving other forage and turf grasses.
Technical Abstract: Linkage analyses increasingly complement cytological and traditional plant breeding techniques by providing valuable information regarding genome organization and transmission genetics of complex polyploid species. This study reports a genome map of buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.). Maternal and paternal maps were constructed with restriction fragment length polymorphisms (RFLPs) segregating in 87 F1 progeny from an intraspecific cross between two heterozygous genotypes. A survey of 862 heterologous cDNAs and gDNAs from across the Poaceae, as well as 443 buffelgrass cDNAs, yielded 100 and 360 polymorphic probes, respectively. The maternal map included 322 RFLPs, 47 linkage groups, and 3464 cM, whereas the paternal map contained 245 RFLPs, 42 linkage groups, and 2757 cM. Approximately 70 to 80% of the buffelgrass genome was covered, and the average marker spacing was 10.8 and 11.3 cM on the respective maps. Preferential pairing was indicated between many linkage groups, which supports cytological reports that buffelgrass is a segmental allotetraploid. More preferential pairing (disomy) was found in the maternal than the paternal parent across linkage groups (55 vs. 38%) and loci (48 vs. 15%). Comparison of interval lengths in 15 allelic bridges indicated significantly less meiotic recombination in parental gametes. Allelic interactions were detected in four regions of the maternal map and were absent in the paternal map.