Submitted to: International Symposium on Molecular Breeding of Forage Crops Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/28/2007
Publication Date: 6/29/2007
Citation: Larson, S.R., Kaur, P., Bushman, B.S., Wang, R., Mott, I.W., Kim, R., Hernandez, A., Thimmapuram, J., Gong, G., Zhang, H. 2007. Evaluation of Leymus LG3a Rhizome QTLs in Four Advanced Backcross Populations and Alignment of Leymus LG3 EST Markers and Oryza Chromosome 1. International Symposium on Molecular Breeding of Forage Crops Proceedings.
Technical Abstract: The genus Leymus comprises about 30 long-lived perennial Triticeae species, including the largest native grasses in the western U.S., distributed throughout cold and/or semiarid growing environments of North and South America, Europe, and Asia. Leymus cinereus and L. triticoides display divergent growth habit and adaptations to different microenvironments in this region. Leymus cinereus is a tall caespitose bunchgrass with high biomass potential and is particularly common near mountain and foothill waterways or valley floodplains. Leymus triticoides is relatively short and strongly rhizomatous with more restricted distribution along streambanks or saline wetlands. Two full-sib families (TTC1 and TTC2) derived from L. triticoides x L. cinereus hybrids backcrossed to the same L. triticoides tester displayed a total of six rhizome spreading QTLs, four of which were located on subgenomic homoeologous regions of the LG3a and LG3b chromosomes in both allotetraploid families. The other rhizome QTLs were specific to TTC1 LG6a and TTC2 LG5Xm. Thus, one particular region on Leymus homoeologous group 3 evidently controls much of the difference in rhizome spreading (growth habit) between L. cinereus and L. triticoides. The genetic map order of 27 LG3a and 20 LG3b Leymus EST or STS markers was strictly collinear with homologous sequences on rice chromosome 1 and wheat homoeologous group 3. Four recombinant BC1 lines were backcrossed again with L. triticoides to evaluate specific segments of the LG3a rhizome QTL in four advanced BC2 populations. The LG3a rhizome QTL was localized to a 40 cM region containing five Leymus EST's and the ortholocus of maize barren stalk1 (ba1) and rice lax panicle (LAX). A nonsense mutation was detected in some Leymus alleles of the Ba1-LAX ortholocus, which maps near the most significant QTL peak observed in the advanced BC2 populations. The 5.3X Leymus BAC library will be screened for this particular gene.