Research Project: Improved Plant Genetic Resources and Methodologies for Rangelands, Pastures, and Turf Landscapes in the Semiarid Western U.S.

Location: Forage and Range Research

2021 Annual Report

Objectives
The semiarid rangelands, irrigated pastures, and turfgrasses of the western U.S. provide a broad array of critical ecosystem services, but invasive weeds, frequent drought, hotter temperatures, wildfires, and other disturbances are increasing the rate of rangeland and pasture degradation and threaten their long-term productivity. Therefore, the long-term objective of the Forage and Range Research Lab (FRR) is to develop resilient, weed resistant, and productive plant materials and methodologies to help prevent and solve these important natural resource issues. Research will be in the areas of (1) Rangeland Conservation and Restoration, and (2) Pasture and Turf Productivity and Sustainability. Specifically, during the next five years we will focus on the following five objectives: Objective 1: Develop new plant materials for pasture, rangeland, and turf systems with increased resilience to harsh and variable environments. Sub-objective 1A: Identify populations of bluebunch wheatgrass wheatgrass [Pseudoroegneria spicata (Pursh) Á. Löve] with superior seedling development under environmental fluctuations. Sub-objective 1B: Elucidate the genetic basis and extent of genotypic variation for drought and salt tolerance in common pasture, rangeland, and turf grasses. Sub-objective 1C: Develop pasture and rangeland grass and legume cultivars and germplasm with improved cold, salt, and drought tolerance. Objective 2: Develop new plant materials and management practices that decrease the impact of invasive species and improve productivity, utility, and restoration of semiarid rangelands. Sub-objective 2A: Develop weed resistant plant materials with improved seed yield, seedling establishment, and persistence for conservation and restoration of rangelands. Sub-objective 2B: Identify seeding methodology that increases establishment of desirable plants and reduces weed invasion on rangelands. Objective 3: Develop new plant materials with improved nutritive value and forage productivity, thereby increasing livestock performance and carrying capacity of pastures and rangelands. Objective 4: Develop new turfgrass plant materials with improved aesthetic value when grown under reduced maintenance conditions. Sub-objective 4A: Identify genetic methods that improve the efficiency of developing reduced-maintenance turfgrass germplasm. Sub-objective 4B: Determine the extent of Genotype x Environment x Management (GxExM) interactions on reduced maintenance turfgrass performance. Objective 5: Identify efficient pasture and rangeland-based grazing strategies that simultaneously improve economic and environmental sustainability of livestock production.

Approach
Traditional plant breeding, augmented by genomics and ecology, multi-location field evaluation, greenhouse microcosm experiment, deficit irrigation and physiological, genomic and molecular marker approaches will be used to achieve project objectives. Sub-objective 1A: Seedling mortality is a threat to revegetation success in semiarid ecosystems. Microcosm experiments will determine the variation for seedling response to environmental gradients of temperature, soil moisture, and nutrients. Sub-objective 1B: Deficit irrigation experiment will determine the feasibility of meadow fescue for the western U.S. Physiological and molecular markers will elucidate the response of turf species to drought and salt stresses; identify and characterize the alien Triticeae genes in wheat that confer salt tolerance and stem rust resistance; and create a DNA map of drought genes in bluebunch wheatgrass. Subobjective 1C: Multi-location evaluation will be employed to develop winter-hardy, drought-tolerant, and/or salt-resistant germplasm of orchardgrass, timothy, and alfalfa. Sub-objective 2A: Native grasses and legumes often lack seed production and establishment. Utah sweetvetch, basalt milkvetch, and Salina wildrye germplasms with improved seed production will be developed. The effect of pre-plant seed treatment on establishment of Utah trefoil will be determined. Genomic selection’s (GS) greatest benefit is when phenotypic evaluation is ineffective; therefore, the potential of GS to improve seed production and establishment in rangeland species will be determined using bluebunch wheatgrass as a model. Subobjective 2B: Many Conservation Reserve Program and Bureau of Land Management plantings in the western U.S. are unsuccessful due to poor establishment of native grasses, legumes and forbs. Seed mixtures that increase seedling establishment success in semiarid regions will be identified. Rapid root development, a potential trait enabling perennial grass seedlings to compete with annual grasses, will be quantified. Objective 3: Recurrent and genomic selection and will develop tall fescue, meadow bromegrass, and tall and intermediate wheatgrass germplasms with improved nutritive value throughout the grazing season. Candidate genes for digestibility will be identified in perennial ryegrass using ribonucleic acid sequencing (RNA-seq) and quantitative trait loci (QTL) analyses. Sub-objective 4A: Kentucky bluegrass and hard fescue have complex genomes that slow their genetic improvement. Genomic and molecular marker approaches will characterize and find functional genes for reduced-maintenance traits. Subobjective 4B: Turfgrass irrigation is not environmentally sustainable, therefore, wheatgrass, bermudagrass, and zoysiagrass will be characterized in mixtures and for color retention in cold temperatures. Objective 5: Reduced dry matter intake (DMI) of pasture by grazing cattle is a major factor limiting livestock performance. Grass-legume pastures that require fewer inputs, have high mass and nutritive value, and have high DMI will be identified.

Progress Report
Progress was made on all five objectives, with the first four objectives under National Program 215, Component 2, Improve the Physiology and Genetics of Animals and Plant Materials for Enhanced Health, Vitality and Utility of Pasture, Biomass for Feed and Fuel, and Rangeland, and Turf Systems, and the fifth objective under NP 215 Component 4, Generate Strategies to Manage Grass, Forage, and Rangeland Agroecosystems that Simultaneously Contribute to Environmental Conservation and are Beneficial to Human and Animal Use. In support of Sub-objective 1A, ARS scientists at Logan, Utah, made progress in identifying populations of bluebunch wheatgrass with superior seedling development under environmental fluctuations. Variation in seed germination and seedling growth and root development rates were evaluated using an automated imaging robot. Experiments were completed at 25 degrees Celsius, but due to COVID restrictions, low temperature experiments were postponed until late-2021. Research also continued determining if bluebunch wheatgrass plants match resource capture strategies to specific soil moisture and nutrient conditions by evaluating seedling nitrogen use and drought stress responses. Progress on Sub-objective 1B included elucidating the genetic basis and extent of genotypic variation for drought and salt tolerance in common pasture, rangeland, and turf grasses. Field-based evaluations of salt tolerance were completed for Kentucky bluegrass, alkaligrass, and perennial ryegrass. Greenhouse screening for drought tolerance in Kentucky bluegrass and perennial ryegrass was completed, as well as a field-based drought tolerance evaluation for perennial ryegrass. Research also continued to develop molecular DNA markers for salinity tolerance and stem rust Ug99 resistance with primer pairs for eight markers of stem rust resistance designed to look for stem rust resistance in a wild relative of wheat. Five putative molecular markers were also identified to trace salinity and drought tolerance in the wild relative. In support of Sub-objective 1C, to develop pasture and rangeland grass and legume cultivars and germplasm with improved cold, salt, and drought tolerance, plant breeding continued to develop orchardgrass and timothy cultivars with increased drought tolerance and winterhardiness. However, due to COVID limitations, evaluation of forage production and nutritive value continued for an additional year at the two Utah and two of the four Canadian sites. Therefore, establishment of orchardgrass and timothy polycross nurseries and peer-reviewed publications were delayed until next year. The development of salt-tolerant alfalfa continued with plants that exhibited superior salt tolerance and high forage production identified and crossed to obtain seed. A manuscript entitled, “Genomic-wide association and prediction of traits related to salt tolerance in autotetraploid alfalfa (Medicago sativa L.)” was published that identified candidate genes associated with enhanced salt tolerance in alfalfa. In addition, Foundation seed, a pending alfalfa cultivar with improved drought tolerance and persistence, was produced and used to establish trials in multiple locations, including some under grazing. For Sub-objective 2A, ARS scientists at Logan, Utah, made progress in developing weed resistant plant materials with improved seed yield, seedling establishment, and persistence for conservation and restoration of rangelands. Genomic selection for improved bluebunch wheatgrass continued with nearly 900 half-sib families of bluebunch wheatgrass seeded into replicated plots in late 2020 and evaluated for seedling emergence in spring of 2021. Results will be integrated with seed-size, plant height, seedling root development, and other data taken from parents of the half-sib families to make genomic prediction models and develop germplasm with improved seedling establishment traits. Preliminary genome sequence assemblies of bluebunch wheatgrass were also completed that will be also be used in development of genomic selection models and to identify genome regions controlling functionally important traits of range grasses. Foundation seed of Utah sweetvetch with improved persistence and seed and forage production was produced pending testing and cultivar release. Finally, recurrent selection continued for the development of improved salina wildrye and non-shattering creeping wildrye germplasms. In support of Sub-objective 2B, we continued identifying seeding methodology that increases establishment of desirable plants and reduces weed invasion on rangelands. Species density, pollinating flowers, and bee estimates were collected on three 32-acre studies in Nephi, Utah, and Malta and Ririe, Idaho, as part of a USDA-Farm Service Agency research grant to study the establishment of pollinator species. The legumes, sainfoin and alfalfa, appeared to provide adequate flowers for bee survival. In a seed mixture study in Nevada, cheatgrass control and native species diversity was greatest in seed mixes where Siberian wheatgrass made up between 40 and 50% of the seed mix. Unfortunately, due to the drought, wild horses had eaten the entire study. Research continued to determine “best-practices” for establishing Utah trefoil with a field trial planted to compare establishment of acid-scarified versus un-scarified seed. Root development rate was evaluated for various bottlebrush squirreltail and Sandberg’s bluegrass varieties that differ in maturity rates. However, contrary to the project plan, growth experiments were conducted in both small pots and transparent growth containers to enhance the characterization of unique root development patterns, and field establishment was monitored at only one site due to seeding failures at the other study site. Follow-up microcosm studies were conducted according to the contingencies described in the Project Plan. In related work, the studies on the how root development of these species influences competitive interactions with invasive annual grasses continued. Contrary to the project plan, mixed-species density competition experiments were replaced with potted-plant studies and conducted at a fixed planting density to precisely quantify differences in water use patterns of each variety and estimate competitive ability. For Objective 3, ARS scientists at Logan, Utah, continued to develop new plant materials with improved nutritive value and forage productivity. Plant Variety Protection applications were submitted for the recently released tall wheatgrass cultivar ‘AlkarXL’ and meadow bromegrass cultivar ‘HighWest’. The analysis of morphological data in support of a putative tall fescue cultivar release, was only partially completed due to COVID restrictions. Development of perennial ryegrass with increased cell wall digestibility continued with the breeding population evaluated for forage quality and DNA extracted for quantitative trait loci (QTL) mapping and genotype by sequencing library creation. Breeding continued in the development of orchardgrass with increased water-soluble carbohydrate concentration. However, due to delay in receiving seed from European cooperators, evaluation of forage yield, nutritive value, and water-soluble carbohydrate concentration continued this year with selections and crosses now scheduled to take place next year. In support of developing a genomic selection model for forage and grain production traits in intermediate wheatgrass, plant establishment and seed yield were evaluated in replicated plots of 900 half-sib families of intermediate wheatgrass. The results will be integrated with seed size, seed shattering, and seed threshing data taken from parent plants of the half-sib families to develop genomic prediction models. A subset of 95 superior genotypes were also selected from a population of 2,233 intermediate wheatgrass plants to be used as the training population for the genomic selection model. As part of a subordinate project (Agreement # 58-2080-1-005), genome sequencing was used to identify, characterize, and select intermediate wheatgrass plants containing each of the 14 chromosomes of durum wheat, and selections were intermated to create a new experimental breeding population. In support of Sub-objective 4A, to identify genetic methods that improve the efficiency of developing reduced maintenance turfgrass germplasm, ARS scientists at Logan, Utah, evaluated hard fescues for disease resistance and wear tolerance in field locations throughout the United States. A hard fescue genome assembly using DNA sequencing was also completed. For Kentucky bluegrass, selected varieties were genotyped using a genotyping by sequencing platform. In support of Sub-objective 4B, to determine the extent of Genotype x Environment x Management interactions on reduced maintenance turfgrass performance, research continued on the development of turf-type germplasms of North American and Eurasian wheatgrass germplasm with improved aesthetics and performance when grown with reduced irrigation and fertilizer. Selection for advanced lines occurred within crested, thickspike, and western wheatgrass populations; plot evaluation nurseries were established for each species. A peer-reviewed journal article was also published. Evaluation of warm-season turfgrass germplasm green color retention when grown in cool temperatures continued. The zoysiagrass cool temperature color retention evaluations were completed, and the data analyzed. In support of Objective 5, to identify efficient pasture and rangeland-based grazing strategies that simultaneously improve economic and environmental sustainability of livestock production, ARS scientists at Logan, Utah, reported in peer-reviewed papers that dairy cattle eat more and have better growth performance when grazing pastures containing mixtures of high-energy grass and the legume birdsfoot trefoil compared to grass only pastures.

Accomplishments
1. Release of the new high yielding and nutritious meadow bromegrass cultivar, ‘HighWest’. Many ranchers are using less productive agricultural lands for pasture as an alternative to public grazing. These areas are often dry, salty, low in soil nutrients, and receive little irrigation making plant establishment and growth difficult. Therefore, ARS researchers in Logan, Utah, developed a new meadow brome named ‘HighWest’ with improved seedling establishment, higher protein and energy, and more forage growth compared to other available cultivars. Not only was HighWest total forage production 23% greater, but regrowth after cutting was nearly twice that of the other cultivars. Furthermore, HighWest had up to six % greater protein and 22% more energy making it an excellent grass for grazing. HighWest meadow brome provides ranchers a new pasture grass with excellent seedling establishment, forage production, and nutritional quality.

2. Dairy cattle eat more when grazing pastures containing mixtures of high-energy grass and the legume birdsfoot trefoil. Milk production from cows grazing pasture is the fastest growing segment of organic agriculture. However, these cows produce up to 32% lower milk, mostly due to eating up to 30% less. ARS researchers in Logan, Utah, in collaboration with researchers at Utah State University, determined how much young dairy cattle eat and grow when grazing four different grasses alone or in mixtures with the legume, birdsfoot trefoil. They found that the grass-birdsfoot trefoil mixtures increased the amount dairy heifers ate by 34%, improved growth by 25%, and resulted in heifers being worth about $166 more than those that ate grass alone. These pasture mixtures are now being used by dairy farmers to increase their cow’s forage intake and milk production.

3. A new basin wildrye with improved seed retention. Great Basin wildrye and other native grasses are planted for livestock grazing, rangeland revegetation, wildlife habitat, and soil conservation in the western United States. On many of these grasses, the seeds shatter and fall to the ground when ripe making it difficult for growers to harvest seed. ARS researchers in Logan, Utah, identified a gene that prevents basin wildrye seed from shattering. They then used DNA markers to select plants and develop a new basin wildrye, ‘L-74X’, with improved seed retention. The improved basin wildrye plants had up to 167% more harvestable seed and 20% better seed germination. This new basin wildrye is now being used as a parent by plant breeders to develop commercial varieties of basin wildrye. The resulting varieties will help farmers produce greater quantity and quality of basin wildrye seed for rangeland revegetation and conservation.

4. Sequencing turfgrass DNA to improve drought tolerance. Record droughts are changing how we grow turf, so plant breeders are working to develop new drought-tolerant turf varieties. Traditional plant breeding is a slow process, especially among the many turf grasses. However, knowing the DNA sequence of turf grasses would allow researchers to quickly identify genes for drought tolerance as well as other important turf traits. Therefore, ARS researchers in Logan, Utah, in collaboration with six other ARS locations and 10 universities, have sequenced the DNA of nine major turf grasses, including Kentucky bluegrass, annual bluegrass, creeping bentgrass, colonial bentgrass, perennial ryegrass, annual ryegrass, hard fescue, bermudagrass, and centipedegrass. These DNA sequences have already been used by ARS, six universities, and three companies to identify genes that are responsible for drought tolerance and disease resistance. This work has potential to fast-track the development of new drought tolerant turf grasses and save billions of gallons of irrigation water.

5. Bluegrass and wheatgrass mixtures have better turf quality and require less irrigation water. Turf is grown on millions of acres, but in the western United States requires large amounts of irrigation water. In contrast, wheatgrasses are common on range and are more drought tolerant but have low turf quality. Therefore, ARS researchers in Logan, Utah, evaluated mixtures of common turfgrasses like Kentucky bluegrass and hard fescue with drought tolerant wheatgrasses when only using 50% or less of normal turf irrigation. They found that the mixtures looked better and had better turf color, cover, and quality than Kentucky bluegrass or the wheatgrasses grown alone. The use of these combinations of turfgrasses can potentially save billions of gallons of water in turf irrigation.

6. First molecular DNA map of bluebunch wheatgrass. Bluebunch wheatgrass is a common grass in the western United States. However, the genetic makeup of bluebunch wheatgrass was not known. Therefore, ARS researchers in Logan, Utah, in collaboration with researchers at Utah State University and Shandong Agricultural University in China, mapped DNA markers to the chromosomes of bluebunch wheatgrass. These DNA markers allowed quantifying the resemblance between bluebunch wheatgrass and wheat, barley, and other wheatgrasses. This work laid the basis for DNA sequencing of bluebunch wheatgrass that will ultimately benefit plant improvement of both the wheatgrasses and cereal crops.

Review Publications
Boe, A., Kephart, K.D., Berdahl, J.D., Peel, M., Brummer, E.C., Xu, L., Wu, Y. 2020. Breeding alfalfa for semiarid regions in the Northern Great Plains: History and additional genetic evaluations of novel germplasm. Agronomy Journal. 10(11). Article 1686. https://doi.org/10.3390/agronomy10111686.
Hong, X., Helong, Y., Mengli, Z., Monaco, T.A., Yuping, R., Ding, H., Qian, S., Kun, Z. 2020. Soil extracellular enzyme activities and the abundance of nitrogen-cycling functional genes responded more to N addition than P addition in an Inner Mongolian meadow steppe. Science of the Total Environment. 741. Article 143541. https://doi.org/10.1016/j.scitotenv.2020.143541.
Benfriha, H., Mefti, M., Robbins, M.D., Thorsted, K., Bushman, B.S. 2021. Molecular characterization of Algerian populations of cocksfoot and tall fescue: Ploidy level determination and genetic diversity analysis. Grassland Science. 67:167-176. https://doi.org/10.1111/grs.12304.
Larsen, R.E., Cook, D., Gardner, D.R., Lee, S.T., Shapero, M., Althouse, L., Dennis, M., Forero, L.C., Davy, J.S., Rao, D.R., Horney, M., Brown, K., Rigby, C.W., Jensen, K.B. 2021. Seasonal changes in forage nutrient and toxicity levels on California central coast rangelands: a preliminary study. Grasslands. 31(1):15-24.
Larsen, R.E., Shapero, M., Striby, K., Althouse, L., Meade, D.E., Brown, K., Horney, M.R., Rao, D.R., Davy, J.S., Rigby, C.W., Jensen, K.B., Dahlgren, R.A. 2021. Forage quantity and quality dynamics due to weathering over the dry season on California annual rangelands. Rangeland Ecology and Management. 76:150-156. https://doi.org/10.1016/j.rama.2021.02.010.
Larson, S.R., Jones, T.A., Johnson, L.M., Waldron, B.L. 2020. Improving seed retention and germination characteristics of North American basin wildrye by marker-assisted gene introgression. Agronomy. 10(11). Article 1740. https://doi.org/10.3390/agronomy10111740.
Zhang, Y., Fan, C., Chen, Y., Wang, R., Zhang, X., Han, F., Hu, Z. 2021. Genome evolution during bread wheat formation unveiled by the distribution dynamics of SSR sequences on chromosomes using FISH. BMC Genomics. 22. Article 55. https://doi.org/10.1186/s12864-020-07364-6.
Rose, M.F., Waldron, B.L., Isom, S.C., Peel, M., Thornton, K., Miller, R., Rood, K., Hadfield, J.A., Long, J., Henderson, B., Creech, J.E. 2021. The effects of organic grass and grass-birdsfoot trefoil pastures on Jersey heifer development: Herbage characteristics affecting intake. Journal of Dairy Science. 104. https://doi.org/10.3168/jds.2020-19563.
Crain, J., Larson, S.R., Dorn, K.M., Kantarski, T., Dehaan, L., Poland, J. 2020. Sequenced-based paternity analysis to improve breeding and identify self-incompatibility loci in intermediate wheatgrass (Thinopyrum intermedium). Theoretical and Applied Genetics. https://doi.org/10.1007/s00122-020-03666-1.
Wang, R., Li, X., Robbins, M.D., Larson, S.R., Bushman, B.S., Jones, T.A., Thomas, A. 2020. DNA sequence-based mapping of the St. genome of Pseudoroegneria spicata (Pursh) A. Love versus wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). Genome. 63:445-457. https://doi.org/10.1139/gen-2019-0152.
Jones, T.A., Bell, B.P., Monaco, T.A. 2021. Perennial grass seedlings modify biomass and physiological traits in response to an annual grass neighbor. Rangeland Ecology and Management. 77:93-100. https://doi.org/10.1016/j.rama.2021.04.001.
Amundsen, K., Warnke, S.E., Bushman, B.S., Robbins, M.D., Martin, R.C., Harris-Shultz, K.R. 2020. Colonial bentgrass transcripts-expression differences compared with creeping bentgrass in response to water-deficit stress. 61(3):2135-2147. Crop Science. https://doi.org/10.1002/csc2.20437.
Monaco, T.A., Gunnell, K.L. 2020. Understory vegetation change following woodland reduction varies by plant community type and seeding status: a region-wide assessment of ecological benefits and risks. Plants. 9(9). Article 1113. https://doi.org/10.3390/plants9091113.
Spackman, C., Monaco, T.A., Stonecipher, C.A., Villalba, J.J. 2020. Plant silicon as a factor in Medusahead (Taeniatherum caput-medusae) invasion. Invasive Plant Science and Management. 13(3):143-154. https://doi.org/10.1017/inp.2020.20.
Robins, J.G. 2021. Breeding and genetics of forages for semi-arid and arid rangelands. Agronomy Journal. 11(4). Article 718. https://doi.org/10.3390/agronomy11040718.
Zinnen, J., Broadhurst, L.M., Gibson-Roy, P., Jones, T.A., Matthews, J.W. 2021. Seed production areas are crucial to conservation outcomes: benefits and risks of an emerging restoration tool. Biodiversity and Conservation Journal. 30:1233-1256. https://doi.org/10.1007/s10531-021-02149-z.
Harris, P.G., Johnson, P.G., Kopp, K., Bushman, B.S. 2021. Inheritance of salt tolerance traits among Kentucky bluegrass hybrids. Crop Science. 61:2113-2120. https://doi.org/10.1002/csc2.20417.
Bushman, B.S., Robbins, M.D., Warnke, S.E., Martin, R.C., Harris-Shultz, K.R., Amundsen, K.E. 2020. Gene expression differences for drought stress response in cool-season turfgrasses. International Turfgrass Society Research Journal. https://doi.org/10.1002/its2.25.
Robins, J.G., Jensen, K.B. 2020. Breeding of the crested wheatgrass complex (Agropyron spp.) for North American temperate rangeland agriculture and conservation. Agronomy Journal. 10(8). Article 1134. https://doi.org/10.3390/agronomy10081134.
Sagers, J., Findlay, J.R., Hatch, J., Shewmaker, G., Jensen, K.B., Hogge, J., Roemer, R., Burr, J.M. 2020. Determining quality and performance of cool season pasture grasses at high elevation in eastern Idaho. Journal of the National Association County Agricultural Agents. 13(1).
Hibbard, C., Hibbard, C., Larson, R., Feuz, R., Rigby, C.W., Jensen, K.B., Larsen, R. 2021. Potential to improve winter grazing pastures: Sieben land and livestock study. Rangelands. 143(3):100-110. https://doi.org/10.1016/j.rala.2020.12.007.
Altendorf, K.R., Larson, S.R., Dehaan, L.R., Crain, J., Neyhart, J., Dorn, K.M., Anderson, J.A. 2021. Nested association mapping reveals the genetic architecture of spike emergence and anthesis timing in intermediate wheatgrass (Thinopyrum intermedium). G3, Genes/Genomes/Genetics. 11(3). Article jkab025. https://doi.org/10.1093/g3journal/jkab025.