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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: Genetic Dissection of Seed Production Traits and Identification of a Major-Effect Seed Retention QTL in Hybrid Leymus (Triticeae) Wildryes

Authors
item Larson, Steven
item Kellogg, Elizabeth - UNIVERSITY OF MISSOURI

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2008
Publication Date: October 15, 2008
Citation: Larson, S.R., Kellogg, E.A. 2009. Genetic Dissection of Seed Production Traits and Identification of a Major-Effect Seed Retention QTL in Hybrid Leymus (Triticeae) Wildryes. Crop Science 49:29-40.

Interpretive Summary: Many native grasses display seed shattering and other seed production problems. Basin wildrye (Leymus cinereus) and creeping wildrye (L. triticoides) are perennial grasses native to western North America. Both of these Leymus wildrye grasses are cultivated for seed used for large-scale rangeland revegetation, forage production, and other conservation uses. In this study, variation in the number of seed-bearing flowers, percent seed set, seed mass, seed shattering, and rate of seed germination was measured in clonally replicated multi-year field evaluations of 164 progeny derived from a backcross between a natural creeping x basin wildrye hybrid and a true creeping wildrye tester. Independent gene effects for all five traits and chromosome region explained 43% of the seed shattering variation and 24% of the variation in seed germination rate. This chromosome region corresponds to the location of seed-shatter gene effects detected in American wildrice (Zizania palustris) and other cultivated cereals. We are using DNA markers to identify and select Leymus wildrye plants with improved seed retention.

Technical Abstract: Many native grasses display seed shattering and other seed production problems. Basin wildrye (Leymus cinereus) and creeping wildrye (L. triticoides) are perennial Triticeae grasses native to western North America. In this study, variation in the number of florets per inflorescence, percent seed set, seed mass, seed shattering, and seed dormancy was measured in clonally replicated multi-year field evaluations of 164 progeny derived from a backcross between a creeping x basin wildrye hybrid and a true creeping wildrye tester. Genome-wide QTL scans detected independent gene effects for all five traits and one pleiotropic QTL, located on Triticeae homoeologous chromosome group 6, associated with major seed shattering (43.1% R2, 26.9 LOD) and seed dormancy (24.1% R2, 10.6 LOD) effects. We hypothesize that a dominant basin wildrye gene creates an abscission that promotes seed disarticulation but hinders seed development and seed ripening in the creeping wildrye backcross family. Alignments of Leymus chromosome 6 EST markers to the Oryza genome demonstrate close alignment of Leymus wildrye and American wildrice (Zizania palustris) seed shatter QTL markers.

Last Modified: 11/26/2014
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