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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED PLANT GENETIC RESOURCES FOR PASTURES AND RANGELANDS IN THE TEMPERATE SEMIARID REGIONS OF THE WESTERN U.S. Title: Development of a new genetic map for testing effects of creeping wildrye genes in basin wildrye backcross populations

Authors
item Yun, Lan -
item Larson, Steven
item Jensen, Kevin
item Robins, Joseph
item Zobel, Dale -

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: December 15, 2012
Publication Date: March 15, 2013
Citation: Yun, L., Larson, S.R., Jensen, K.B., Robins, J.G., Zobel, D. 2013. Development of a new genetic map for testing effects of creeping wildrye genes in basin wildrye backcross populations. Meeting Abstract.

Technical Abstract: Basin wildrye (Leymus cinereus) is the largest native grass in western North America. Creeping wildrye (Leymus triticoides) is strongly rhizomatous grass that forms fertile hybrids with basin wildrye. Inter-specific hybrids, designated "TC" from the species epithets, display biomass heterosis and a potentially useful combination of traits including rhizomes. Two full-sib genetic mapping populations, designated TTC1 and TTC2, were previously developed from backcrosses from two TC hybrids with creeping wildrye for identification of genes controlling biomass and other functionally important traits. Basin wildrye contributed eight positive biomass QTLs in the TTC creeping wildrye backcrosses, which may be partly explained by genes that increased stem length and width. However, QTL analyses of the TTC mapping populations did not adequately explain biomass heterosis of the TC hybrids nor did they fully account for divergence between these species, presumably because dominant creeping wildrye alleles could not be detected in the creeping wildrye backcross. A new full-sib genetic mapping population, described here, comprised of 250 genotypes was created from a backcross of a TC hybrid to basin wildrye. This population, designated TCC, was developed to test the effect creeping wildrye genes in the basin wildrye background. Creeping wildrye contributed two of the three positive biomass QTLs in the TCC basin wildrye backcross, which may be partly explained by genes that increase tiller number. Comparisons between the TTC and TCC populations indicate that ten of the eleven biomass QTLs were dominant, which explain heterosis of creeping x basin wildrye hybrids. One rhizome QTL was conserved in both TTC and TCC families, which evidently has strong dominant effects in the TCC family. Thus, the new TCC basin wildrye backcross population may also provide a useful system for identification of a major-effect rhizome gene. Although genes controlling rhizome spreading were not associated with biomass yield, these genes may contribute clipping and grazing tolerance in perennial grasses.

Last Modified: 12/19/2014
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