Native Grasses for Biomass Production at High Elevations - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 104

basins and nonsaline soils of the upland sagebrush/grassland environments
[ 17 ]. Basin wildrye was presumably once abundant on more productive soils of
the intermountain valleys and floodplains that are now cultivated croplands and
pastures [ 16 ]. Basin wildrye supplements tall wheatgrass in saline pastures, where it
is grazed in the spring and fall [ 18 - 20 ], and provides valuable forage for winter
grazing across western rangelands [ 16 , 21 , 22 ]. Basin wildrye is primarily used for
large-scale rangeland rehabilitation, erosion control, and other conservation uses
throughout western North America [ 23 ]. It is recommended for areas receiving
250-400-mm precipitation [ 21 ], but is often found growing in drier saline desert
basins where surface or subsurface moisture may accumulate [ 24 - 26 ]. Basin
wildrye has demonstrated tolerance to phytotoxic soils contaminated by heavy
metals and is one of the more useful native grasses for mine reclamation in the
western USA [ 27 - 30 ]. Although crops and forages grown on contaminated soils
may pose health risks to humans and livestock, these areas may be suitable for
biofuel production if the contaminants can be properly managed.
Creeping wildrye is commonly found on harsh alkaline sites in California,
Nevada, Utah, and southeast Oregon [ 7 , 21 ]. Creeping wildrye may have been
one of the dominant species in the prairies and lowland oak woodlands of the
California Central Valley [ 31 ]. Creeping wildrye is primarily used for soil stabili-
zation, especially along channel or river banks, and for wildlife habitat in wetland
and riparian plantings [ 14 ]. It is also recommended for use as forage and for
reclamation of croplands and pasturelands contaminated by saline irrigation water
[ 14 ]. The salt tolerance of creeping wildrye approaches that of tall wheatgrass and
both species are being evaluated for forage and biomass production using saline
irrigation water in the San Joaquin Valley of central California [ 32 - 34 ].

Genetic Resources

Next to Thinopyrum (wheatgrass), species in the genus Leymus have been of
greatest interest to Triticeae grain breeders since the early 1940s when N. V. Tsitsin
initiated hybridizations between Leymus and the Triticeae cereal genera Triticum ,
Hordeum , and Secale [ 15 , 35 ]. Several Leymus species have been successfully
hybridized with wheat, and some of the resulting introgression lines display poten-
tially useful traits including biological nitrification inhibition [ 36 ], resistance to
Fusarium head blight [ 37 - 39 ], and salt tolerance [ 40 ]. The genus Leymus are
comprised of allopolyploid member species that contain the Ns genome of
Psathyrostachys (Russian wildrye) and the J genome of Thinopyrum , based on
chromosome pairing of interspecific hybrids [ 35 ]. However, early cytogenetic
experiments raised doubt on the putative genome relationship between Leymus
and Thinopyrum , which led to the currently accepted NsXm subgenome designa-
tions where Xm is from an unknown diploid ancestor [ 41 , 42 ]. In any case, it is
should be relatively easy to hybridize species and transfer chromosomes or genes
between congeneric Leymus species, but

introgression between genomically