Joseph G. Robins

Orchardgrass (Dactylis glomerata L.) EST and SSR marker development, annotation, and transferability.

Orchardgrass, or cocksfoot [Dactylis glomerata (L.)], has been naturalized on nearly every continent and is a commonly used species for forage and hay production. All major cultivated varieties of orchardgrass are autotetraploid, and few tools or information are available for functional and comparative genetic analyses and improvement of the species. To improve the genetic resources for orchardgrass, we have developed an EST library and SSR markers from salt, drought, and cold stressed tissues. The ESTs were bi-directionally sequenced from clones and combined into 17,373 unigenes. Unigenes were annotated based on putative orthology to genes from rice, Triticeae grasses, other Poaceae, Arabidopsis, and the non-redundant database of the NCBI. Of 1,162 SSR markers developed, approximately 80% showed amplification products across a set of orchardgrass germplasm, and 40% across related Festuca and Lolium species. When orchardgrass subspecies were genotyped using 33 SSR markers their within-accession similarity values ranged from 0.44 to 0.71, with Mediterranean accessions having a higher similarity. The total number of genotyped bands was greater for tetraploid accessions compared to diploid accessions. Clustering analysis indicated grouping of Mediterranean subspecies and central Asian subspecies, while the D. glomerata ssp. aschersoniana was closest related to three cultivated varieties.

Stand Establishment and Persistence of Perennial Cool-Season Grasses in the Intermountain West and the Central and Northern Great Plains

Abstract The choice of plant materials is an important component of revegetation following disturbance. To determine the utility and effectiveness of various perennial grass species for revegetation on varied landscapes, a meta analysis was used to evaluate the stand establishment and persistence of 18 perennial cool-season grass species in 34 field studies in the Intermountain and Great Plains regions of the United States under monoculture conditions. Combined across the 34 studies, stand establishment values ranged from 79% to 43% and stand persistence values ranged from 70% to 0%. Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D. R. Dewey), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), crested wheatgrass (Agropyron spp.), Siberian wheatgrass (Agropyron fragile [Roth] P. Candargy), and meadow brome (Bromus riparius Rehmann) possessed the highest stand establishment (≥ 69%). There were no significant differences among the 12 species with the largest stand persistence values. Basin wildrye (Leymus cinereus (Scribn. & Merr.) Á. Löve), Altai wildrye (Leymus angustus [Trin.] Pilg.), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners), squirreltail (Elymus spp.), and Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth) possessed lower stand persistence (≤ 32%) than the majority of the other species, and Indian ricegrass (0%) possessed the lowest stand persistence of any of the species. Correlations between environmental conditions and stand establishment and persistence showed mean annual study precipitation to have the most consistent, although moderate effect (r = ∼0.40) for establishment and persistence. This relationship was shown by the relatively poor stand establishment and persistence of most species at sites receiving less than 310 mm of annual precipitation. These results will be a tool for land managers to make decisions concerning the importance of stand establishment, stand persistence, and annual precipitation for revegetation projects on disturbed sites.

A molecular genetic linkage map identifying the St and H subgenomes of Elymus (Poaceae: Triticeae) wheatgrass

Elymus L. is the largest and most complex genus in the Triticeae tribe of grasses with approximately 150 polyploid perennial species occurring worldwide. We report here the first genetic linkage map for Elymus. Backcross mapping populations were created by crossing caespitose Elymus wawawaiensis (EW) (Snake River wheatgrass) and rhizomatous Elymus lanceolatus (EL) (thickspike wheatgrass) to produce F(1) interspecific hybrids that were then backcrossed to the same EL male to generate progeny with segregating phenotypes. EW and EL are both allotetraploid species (n = 14) containing the St (Pseudoroegneria) and H (Hordeum) genomes. A total of 387 backcross progeny from four populations were genotyped using 399 AFLP and 116 EST-based SSR and STS markers. The resulting consensus map was 2574 cM in length apportioned among the expected number of 14 linkage groups. EST-based SSR and STS markers with homology to rice genome sequences were used to identify Elymus linkage groups homoeologous to chromosomes 1-7 of wheat. The frequency of St-derived genome markers on each linkage group was used to assign genome designations to all linkage groups, resulting in the identification of the seven St and seven H linkage groups of Elymus. This map also confirms the alloploidy and disomic chromosome pairing and segregation of Elymus and will be useful in identifying QTLs controlling perennial grass traits in this genus.

Color and Shoot Regrowth of Turf-type Crested Wheatgrass Managed Under Deficit Irrigation

An increased demand on limited water supplies has led to a growing interest in turfgrasses tolerant of lower irrigation regimes. One potential source of droughthardy turfgrass is the perennial Triticeae wheatgrasses. These grasses have thrived in semi-arid regions, mainly through dormancy in the dry periods. However, dormancy is undesirable in residential and commercial settings where irrigation can be applied regularly. In this study we used a line-source gradient of irrigation on seven species of turf-type grasses, with a primary focus on crested wheatgrass. Our objective was to determine what level of irrigation will prevent dormancy in crested wheatgrass, and compare the color and shoot regrowth after mowing between it and the other turfgrass species at different irrigation levels. The crested wheatgrasses did not enter dormancy under the moderate irrigation level of approximately 60% evapotranspiration replacement. Under all irrigation levels, tall fescue and Kentucky bluegrass had the highest color ratings, due to genetically darker color. Shoot regrowth differences between the species were minimal, and also indicated dormancy only under the lowest irrigation levels.

Comparative trends in forage nutritional quality across the growing season in 13 grasses

Abstract: The objective of the Conservation Reserve Program (CRP) is to convert erodible cropland to perennial vegetation. Under severe drought, CRP land is frequently utilized for grazing; thus, there is a need to better understand trends in forage nutritional quality in species used in CRP plantings. This study evaluated 13 cool-season irrigated and dryland grasses from May to August and regrowth from September to November in northern Utah during 2004 and 2005 for crude protein (CP), neutral detergent fiber digestibility (NDFD), in vitro true digestibility (IVTD), and neutral detergent fiber (NDF) values. Species, sampling date, year, and sampling date × species interaction had a significant (P < 0.05) effect on CP, NDFD, IVTD, and NDF values. From May to August, there was a strong linear decline in CP, NDFD, and IVTD values. Mean CP values ranged from 68 to 251 g kg-1 in all species examined. Orchardgrass, smooth bromegrass, RS-hybrid, and crested wheatgrass had CP, NDFD, and IVTD values similar to orchardgrass and timothy, but less than perennial ryegrass. Crested wheatgrass had NDF values similar to timothy, but less than orchardgrass. Crested wheatgrass and smooth bromegrass had the greatest nutritional quality and were often similar to orchardgrass, tall fescue, and timothy.

Relationships among seed quality characteristics in a collection of western wheatgrass germplasms

Although western wheatgrass [Pascopyrum smithii (Rydb.)] is an important perennial grass species for agriculture and conservation management in central and western North America, its lack of adequate seed production and seedling vigor limits its effectiveness. To address the weaknesses a study was conducted to assess rhizome spread, seed production, seed weight, germination percentage, and emergence rate of seed produced from 48 western wheatgrass cultivars and germplasm accessions at a field site near Nephi, UT, USA during 2007 and 2008. The western wheatgrass cultivars had approximately two times higher seed production than the germplasm accessions during both 2007 and 2008 and also had higher seed weight in 2007 and emergence rate in 2008. The germplasm accessions had higher seed weight in 2008. For the remaining traits there were no differences among the different germplasm sources. Based on principle component analysis a subset of cultivars and germplasm accessions with high seed production and emergence rate were identified that could be used to produce improved cultivars and germplasms. There was little evidence of strong relationship between geographic, genetic, and phenotypic distances among the various lines examined. Additionally, based on genetic marker data, a subset of lines was grouped into three populations. Based on these results, selection among lines could occur to maximize agricultural performance regardless of site of origin, or within population selection could be practiced to meet conservation goals of minimizing hybridization among populations.

Identification of thickspike wheatgrass accessions with superior rhizome spread, seed production, and seed quality

Thickspike wheatgrass (Elymus lanceolatus (Scribn. & J.G. Sm.) Gould [Poaceae]) accessions evaluated for performance in the Intermountain/Great Basin region of the US differed significantly (P = 0.05) for several agronomic and seed quality traits. In this study, 50 accessions of thickspike wheatgrass, including all accessions in the USDA National Plant Germplasm System collection and 5 cultivars were characterized for rhizome spread and seed production at a site near Eureka, Utah, during 2007 and 2008. The resulting seeds from both production years were then further evaluated in laboratory and greenhouse experiments for germination percentage, seed weight, emergence rate, and total emergence after deep seeding. Significant interaction between the accessions and the year of production necessitated characterization of results within each year of production, rather than across years. The Utah Experimental population was among the highest performing accessions for 4 of the traits in at least one of the years of the study. None of the accessions, however, were among the high performers for all 6 evaluated traits. Based on summation of accession standard normalized mean variables for each trait, several accessions including 552794 from Colorado and 562039 from Wyoming showed promise for combining good performance for most of the traits for production in the Intermountain/Great Basin region. Accessions from outside this area were poorly adapted. Thus, untapped potential exists to cultivate thickspike wheat-grass seed sources with higher seed production and seed quality than are now commercially available.

Effects of Elevated CO2 on the Swainsonine Chemotypes of Astragalus lentiginosus and Astragalus mollissimus

Rapid changes in the Earth’s atmosphere and climate associated with human activity can have significant impacts on agriculture including livestock production. CO2 concentration has risen from the industrial revolution to the current time, and is expected to continue to rise. Climatic changes alter physiological processes, growth, and development in numerous plant species, potentially changing concentrations of plant secondary compounds. These physiological changes may influence plant population density, growth, fitness, and toxin concentrations and thus influence the risk of toxic plants to grazing livestock. Locoweeds, swainsonine-containing Astragalus species, are one group of plants that may be influenced by climate change. We evaluated how two different swainsonine-containing Astragalus species responded to elevated CO2 concentrations. Measurements of biomass, crude protein, water soluble carbohydrates and swainsonine concentrations were measured in two chemotypes (positive and negative for swainsonine) of each species after growth at CO2 levels near present day and at projected future concentrations. Biomass and water soluble carbohydrate concentrations responded positively while crude protein concentrations responded negatively to elevated CO2 in the two species. Swainsonine concentrations were not strongly affected by elevated CO2 in the two species. In the different chemotypes, biomass responded negatively and crude protein concentrations responded positively in the swainsonine-positive plants compared to the swainsonine-negative plants. Ultimately, changes in CO2 and endophyte status will likely alter multiple physiological responses in toxic plants such as locoweed, but it is difficult to predict how these changes will impact plant herbivore interactions.

A History of Plant Improvement by the USDA-ARS Forage and Range Research Laboratory for Rehabilitation of Degraded Western U.S. Rangelands

On the Ground Climate change models for the western United States predict warmer winters in the Great Basin and hotter, drier summers in the Mojave Desert, increasing the already high rate of rangeland and pasture degradation, which in turnwill increase annual grass invasion, escalate wildfire frequency, and reduce forage production. These changes in western U.S. rangelands will continue to result in the emergence of novel ecosystems that will require different and/or improved plant materials for successful revegetation. Traditional plant improvement of native and non-native rangeland plant species by the USDA, ARS Forage and Range Research Laboratory (FRRL, Logan, Utah) has been accomplished through rigorous evaluation of seed collections followed by recurrent selection and hybridization of unique plant types within selected populations to identify plants with superior establishment and performance characteristics. After such plant types have been selected, they are further evaluated in multiple ecologically diverse locations to identify broadly adapted superior germplasm for public release. Plant improvement of perennial grasses, legumes, and forbs by the FRRL has provided and will continue to deliver plant materials that support sustainable rangeland management efforts to service productive and functionally diverse rangelands.

Current Status of Feed Quality Breeding and Testing in North America

Although selection for improved feed quality is an important objective for many North American forage breeding programs, especially for those based in dairy regions, it is generally of secondary importance to improved forage mass, persistence, and stress tolerance. The advent of more efficient and high-throughput phenotyping and genotyping procedures will decrease the cost of feed quality analysis and increase the efficiency of trait improvement. At the FRRL, our main focus is forage mass and abiotic stress tolerance in limited precipitation regions. We also seek to develop forage cultivars with increased feed quality. Current breeding populations and molecular biological tools allow us to better dissect the genetics of these traits and incorporate them into improved cultivars.