Native Grasses for Biomass Production at High Elevations - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 105

defined Triticeae genera requires more sophisticated breeding and cytogenetic
techniques [ 35 , 43 ]. Most Leymus species are allotetraploid (2 n ¼ 4 x ¼ 28); how-

ever, octoploid (2 n 84) species and races

exist. About 40 % of the surveyed basin wildrye accessions are tetraploid as are all
creeping wildrye accessions [ 44 ]. However, the majority of basin wildrye acces-
sions are octoploid.
Genetic markers and maps have been specifically developed for gene discovery
and breeding research using hybrids of basin and creeping wildryes. Nearly 1,800
simple sequence repeat (SSR) markers were designed from 11,281 expressed gene
sequence tags (ESTs) from creeping x basin wildrye hybrids [ 45 ]. Most of the
12,000 Leymus ESTs have been aligned to Brachypodium , and other grass genome
reference sequences on the biofuel feedstock genomics resource from Michigan
State University ( http://bfgr.plantbiology.msu.edu/ ) and GrainGenes [ 46 ]. Three
full-sib genetic mapping populations comprised of 586 progenies from reciprocal
backcrosses of creeping x basin wildrye hybrids to creeping and basin wildrye
testers were developed to map genes and markers associated with functionally
important trait differences between these species [ 46 - 48 ]. Molecular genetic
maps were constructed by genotyping these highly polymorphic mapping
populations using nearly 2,000 DNA markers including 435 Leymus EST and
28 marker loci for nine of the ten known lignin biosynthesis genes. A large-insert
bacterial artificial chromosome (BAC) libraries were developed from a creeping x
basin wildrye hybrid including 405,888 clones with an estimated average length of
150.5 kb per insert, which represents 6.1 haploid genome equivalents of these
allotetraploid Leymus wildryes [ 49 ]. These experimental plant materials and
DNA libraries provide valuable tools for gene discovery research and plant
breeding.
The USDA National Plant Germplasm System (NPGS) currently holds
242 accessions of basin wildrye and 20 creeping wildrye accessions. Three geo-
graphically significant landraces of basin wildrye were identified by DNA analysis
of the NPGS accessions [ 44 ]. The Columbia race extends from British Columbia in
the north, south through the Columbia River Plateau of Washington and Oregon,
and further south into the Sierra Steppe of southeastern Oregon and northern
California. About 91 % of the accessions classified in the Columbia race were
octoploid. The Rocky Mountain race extends from the Rocky Mountain Piedmont
of Alberta and Montana in the north; south through Wyoming, Utah, and Colorado;
and west across the Snake River Plateau of Idaho and the Intermountain region of
Nevada and Utah. About 82 % of the accessions classified in the Rocky Mountain
race were tetraploid. The Great Basin race is interspersed with the Rocky Mountain
accessions, but it is restricted to the Great Basin region of southwestern Idaho,
Nevada, and western Utah. The Great Basin race is genetically more similar to the
Rocky Mountain race, but like most of the accessions from the Columbia race, 73 %
of the Mountain race accessions are octoploid.

¼ 8 x ¼ 56) and duodecaploid (2 n ¼ 12 x ¼