Submitted to: Functional and Integrative Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2008
Publication Date: 6/15/2008
Citation: Kaur, P., Larson, S.R., Bushman, B.S., Wang, R., Hole, D., Thimmapuram, J., Gong, G., Liu, L., Mott, I.W. 2008. Genes Controlling Plant Growth Habit in Leymus (Triticeae); Maize Barren Stalk1 (Bal), Rice Lax Panicle, and Wheat Tiller Inhibition (Tin3) Genes as Possible Candidates. Functional and Integrative Genomics 8:375-386
Interpretive Summary: Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) are relatively large perennial grasses native to western North America. Creeping wildrye has strong aggressive rhizomes, which promote lateral growth and tillering, whereas basin wildrye is considered one of the tallest grasses in western North America. Interspecific hybrids of basin wildrye and creeping wildrye display a combination of traits, including tall plant height and strong rhizomatous tillering, which may be useful as a regionally adapted feedstock with relatively high seasonal biomass accumulation potential. Previous studies detected chromosome regions controlling rhizome spreading in two experimental breeding families derived from hybrids of basin wildrye and creeping wildrye. In this report, we describe the isolation and targeted genetic mapping of 44 new Leymus gene sequences associated with chromosome regions controlling rhizome spreading. Leymus wildrye gene sequences associated with rhizome spreading were aligned to a region on the distal long arm of rice chromosome 1, containing less than 5 million base-pairs of DNA. This region of the rice genome also contains genes known to control tillering in maize, rice, and wheat. Results of this study have been used to identify genes and markers needed to develop Leymus wildrye hybrids with improved establishment and biomass production.
Technical Abstract: Leymus cinereus and L. triticoides are large caespitose and rhizomatous perennial grasses, respectively. Previous studies detected QTLs controlling rhizome spreading on linkage groups (LG) LG3a and LG3b in two families, TTC1 and TTC2, derived from L. triticoides x L. cinereus hybrids. Triticeae group 3 is reportedly collinear with rice chromosome 1, but previous studies suggested rearrangements of Leymus group 3 in wheat-Leymus racemosus chromosome addition lines. In this report, we describe development and targeted mapping of 44 new Leymus EST microsatellite markers, based on rice chromosome 1 alignments. Thirty-eight of the 44 informative Leymus EST microsatellite markers detected 23 and 17 loci on the Leymus LG3a and/or LG3b target groups, respectively, which are collinear with homologous sequences on rice chromosome 1. Most of these Leymus EST markers were syntenous in putative homoeologous group 3 wheat-Leymus and -Thinopyrum addition lines. The Leymus LG3a and LG3b growth habit QTLs were aligned to a 5 Mb region on the distal long arm of rice chromosome 1, which also aligns to the wheat tiller inhibition gene on Triticum monococcum chromosome 3AmL. Comparisons of genetic recombination in Leymus and physical distance in rice suggest relatively high recombination rates in the Leymus growth habit QTL regions.