Research Project: Improving Forage and Bioenergy Plants and Production Systems for the Central U.S.

Location: Wheat, Sorghum and Forage Research

2020 Annual Report

Objectives
1. Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources. (NP215 1A, 2C, 4B, 4C) 2. Develop new forage and biomass germplasm and cultivars for central U.S. growing conditions. (NP215 1A, 2C) 3. Identify molecular, biochemical and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. (NP215 1A, 2C)

Approach
Project objectives are to develop best management practices for annual and perennial grasses for livestock production, provide feedstocks for bioenergy, develop new forage and biomass cultivars for the central U.S., and identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production and complement breeding and management research. Perennial grass breeding techniques will be refined to design improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of new cultivars by enhancing establishment, yield, and utilization by livestock and by the bioenergy industry. Molecular biology and biochemistry/physiology information will be utilized to improve breeding and management products. The project is a continuation of a long-term perennial grass research program with plant materials, management, and related studies in various stages of development and completion. Research will be conducted on C3 (cool-season) and C4 (warm-season) perennial grasses, and C3 annual grasses. All are needed to maximize the length of the growing season and more fully utilize available land. Switchgrass, big bluestem, and indiangrass are the primary C4 species being evaluated for use in livestock and/or bioenergy production systems. Triticale, a winter annual, will be developed for forage/cover crop use as a double-crop option with early spring grazing and improved soil conservation. New technologies from this research, when utilized on 6 million hectares in the Midwest, could produce biofuels for 15 million cars, increase beef production per hectare by 10%, and increase early spring forage production by 6 million animal unit months.

Progress Report
The project has three main components, breeding, management, and molecular biology/biochemistry. This project leads the development of switchgrass into a biomass energy crop and has numerous collaborations. This project has developed most of the grasses and associated management information used for grassland reseeding in the central USA, and much of the management information for switchgrass grown as a biomass energy crop. Fundamental science has been developed on cell wall properties and their genetic control, and information and data are being used extensively in switchgrass genomics. The overall objectives of this continuing long-term project are to develop improved perennial grasses, management practices, and technologies for use in grazing lands and biomass energy production systems in the central USA. Over the next five years, the following specific objectives will be addressed. (1) Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation's natural resources; (2) Develop new forage and biomass germplasm and cultivars for central US growing conditions; and (3) Identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. Objective 1: Research focuses on developing best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation's natural resources. In Subobjective 1A, integrated crop-livestock systems for the Great Plains that include smooth bromegrass, switchgrass, triticale, wheat, rye, corn, and soybeans are being evaluated. The smooth bromegrass has produced steer average daily gains (ADG) of up to 4 lbs/head/day and the switchgrass components have produced ADG of about 1 lb/head/day. The Shawnee switchgrass is being converted to a warm-season grass mix to provide increased animal performance. Grazing wheat, rye, and triticale in the spring before soybeans produced an ADG of 3.9 to 4.1 lbs/hd/day in 29 grazing days. In the first 16 years of growing switchgrass and no-till corn on marginally productive cropland, N and harvest management have a significant impact on biomass yield, soil organic carbon (SOC), and greenhouse gas emissions (GHG). Increased SOC was the major GHG sink in all feedstock systems, but net agronomic GHG outcomes hinged on soil nitrous oxide emissions controlled by N fertilizer rate. This long-term field study is the first to demonstrate that annual crop and perennial grass systems respectively maintain or mitigate atmospheric GHG contributions during the agronomic phase of bioenergy production, providing flexibility for land-use decisions on marginally productive croplands. Field-scale production of Liberty switchgrass, big bluestem, and a low-diversity warm-season grass mixture continues with reduced N rates to evaluate biomass and GHG emissions. Additionally, 'Independence', a new switchgrass cultivar, was planted at the site in spring 2019. In the previous 7 years, this marginally productive site in eastern Nebraska has reliably produced 5 U.S. tons/acre per year to meet potential feedstock demands for the bioeconomy. Objective 2: Research focuses on developing new forage and biomass germplasm and cultivars for the central USA. In Subobjective 2A, five perennial grass species are being bred for both livestock and bioenergy production systems. Breeding values of both parents and progeny have been quantified in multi-generational analyses. A genomic selection framework using quantitative trait locus mapping, classical genetics, physiology, transcriptomics, and virology has been evaluated to maximize the genetic potential of switchgrass for biomass and lignin yield and disease resistance. Two progeny tests of switchgrass have been planted in the field. Harvests of 4 bromegrass progeny tests have been completed. Three open-pollinated crossing nurseries of Indiangrass have been field planted. Two types of regional trials were planted, one for cultivar and germplasm release and one for evaluating GxE interactions. In Subobjective 2B, field evaluations have been initiated to determine the relative importance of additive and dominance genetic variation in switchgrass. Ramets were collected from the field, planted into pots, and crossed in the greenhouse. In Subobjective 2C, tetraploid and octoploid switchgrass crosses were completed in the greenhouse to transfer genes for adaptation and yield and increase genetic diversity. Ramets were collected from the field, planted into pots, and crossed in the greenhouse. Data collected from field-grown plants are being analyzed. In Subobjective 2D, phenotypic data have been collected and most of the previous progeny generations were genotyped by sequencing (GBS). The final cycle of progeny testing was planted in the field and some data analysis has been initiated. Crosses were made for the mapping population and one was chosen and transplanted into the field. In Subobjective 2E, an additional year of biomass yield was collected, but early spring green-up evaluation was delayed due to COVID-19. Consequently, the combined traits of early spring green-up and yield are missing and will be collected in 2021 to identify candidate lines for advancement. Objective 3: Research focuses on molecular, biochemical, and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. Related work was initiated but has currently been suspended due to maximized telework. Subobjective 3A has been suspended due to loss of field replicates. In Subobjective 3B, tillers from twelve plants were collected after a killing frost in November 2019. Plant material has been dried, but further processing has been halted. It is anticipated that clonal replication of plants will be completed in spring of 2021, if conditions so permit. For Subobjective 3C, the presence and expression of genes uniquely present in leaves of upland and lowland cultivars of switchgrass has been published. This study demonstrated that the lowland cultivar 'Kanlow' possessed greater expression of defense-related genes under control conditions, potentially accounting for its better resistance to plant pathogens as compared to the more susceptible upland cultivar 'Summer'. Other work mined expression datasets from rhizomes sampled throughout a growing season from cultivar 'Kanlow' to discover potential pathways and genes unique to the lowland cultivar compared to the upland cultivar 'Summer'.

Accomplishments
1. Management controls the net greenhouse gas outcomes of growing bioenergy feedstocks on marginally productive croplands. Bio-based energy is key to developing a globally sustainable low-carbon economy. Lignocellulosic feedstock production on marginally productive croplands is expected to provide substantial climate mitigation benefits, but long-term field research comparing greenhouse gas (GHG) outcomes during the production of annual versus perennial crop-based feedstocks is lacking. Researchers in Lincoln, Nebraska, and Fort Collins, Colorado, determined that long-term (16 years) switchgrass (Panicum virgatum L.) systems mitigate GHG emissions during the feedstock production phase compared to GHG-neutral continuous corn (Zea mays L.) under conservation management. Increased soil organic carbon was the major GHG sink in all feedstock systems, but net agronomic GHG outcomes hinged on soil nitrous oxide emissions controlled by nitrogen fertilizer rate. This field study is the first to demonstrate that annual crop and perennial grass systems respectively maintain or mitigate atmospheric GHG contributions during the agronomic phase of bioenergy production, providing flexibility for land-use decisions on marginally productive croplands.

2. Expression of defense-related genes differentiate lowland and upland switchgrass cultivars. Switchgrass is a native perennial that can provide a sustainable supply of biomass on marginal lands. This biomass can have multiple end uses, including those as a feedstock for bioenergy. Upland and lowland cultivars of switchgrass can differ in their ability to withstand attack by plant pathogens. Possible molecular dynamics that drive these differences in non-infected plants have not been assessed. Here, the 4th emerging leaf from greenhouse grown Kanlow (lowland) and Summer (upland) switchgrass cultivars were collected from emergence through leaf senescence. RNA extracted from these leaves were subjected to high-throughput next generation sequencing. Researchers in Lincoln, Nebraska, analyzed data which indicated similar and cultivar-specific changes in gene expression. Overall development of leaf functions and transition to senescence were similar; however, Kanlow plants had a much greater number of expressed genes that could be involved in defense against pathogens. These data suggested that Kanlow plants could provide useful traits for the continued improvement of switchgrass germplasm with improved disease resistance.

Review Publications
Souza, D., Jimenez, A.V., Sarath, G., Meinke, L.J., Miller, N.J., Siegfried, B.D. 2020. Enhanced metabolism and selection of pyrethroid-resistant western corn rootworms (diabrotica virgifera virgifera leconte). Pesticide Biochemistry and Physiology. 164:165-172. https://doi.org/10.1016/j.pestbp.2020.01.009.
Becana, M., Yruela, I., Sarath, G., Catalan, P., Hargrove, M.S. 2020. Plant hemoglobins: a journey from unicellular green algae to vascular plants. New Phytologist. Tansley review 1-18. https://doi.org/10.1111/nph.16444.
Kumar, S., Sood, K., Sieverding, H., Thandiwe, N., Bly, A., Wienhold, B.J., Redfearn, D., Archer, D.W., Ussiri, D., Faust, D.R., Landblom, D., Grings, E., Stone, J., Jacquet, J., Pokharel, K.P., Liebig, M.A., Schmer, M.R., Sexton, P., Mitchell, R., Smalley, S., Osborne, S.L., Ali, S., Senturklu, S., Sehgal, S., Owens, V., Jin, V.L. 2019. Facilitating crop–livestock reintegration in the northern great plains. Agriculture, Ecosystems and Environment. 111(5):2141-2156. https://doi.org/10.2134/agronj2018.07.0441.
Jin, V.L., Schmer, M.R., Stewart, C.E., Mitchell, R., Williams, C.O., Wienhold, B.J., Varvel, G.E., Follett, R.F., Vogel, K.P., Kimble, J. 2019. Management controls the net greenhouse gas outcomes of growing bioenergy feedstocks on marginally productive croplands. Science Advances. 5(12):1-6. https://doi.org/10.1126/sciadv.aav9318.
Lowry, D.B., Lovell, J.T., Zhang, L., Bonnette, J., Fay, P.A., Mitchell, R., Lloyd-Reilley, J., Boe, A.R., Wu, Y., Rouquette, F.M., Wynia, R.L., Weng, X., Behrman, K.D., Healey, A., Barry, K., Lipzen, A., Bauer, D., Sharma, A., Jenkins, J., Schmutz, J., Fritschi, F.B., Juenger, T.E. 2019. QTL x environment interactions underlie adaptive divergence in switchgrass across a large latitudinal gradient. Proceedings of the National Academy of Sciences. 116(26):12933-12941. https://doi.org/10.1073/pnas.1821543116.
Palmer, N.A., Rekalakunta Venka, C., Muhle, A., Tatineni, S., Yuen, G., Edme, S.J., Mitchell, R., Sarath, G. 2019. Transcriptome divergence during leaf development in two contrasting switchgrass (Panicum virgatum L.) cultivars. PLoS One. 14(9):e0222080. https://doi.org/10.1371/journal.pone.0222080.
Tetreault, H.M., Gries, T.L., Palmer, N.A., Funnell-Harris, D.L., Sarath, G., Sattler, S.E., Sato, S., Ge, Z. 2020. Overexpression of ferulate 5-hydroxylase increases syringyl units in Sorghum bicolor. Plant Molecular Biology. 103(3):269-285. https://doi.org/10.1007/s11103-020-00991-3.
Chanbusarakum, L.J., Bragg, J.N., Cheng, P.K., Aucar, S., Sarath, G., Palmer, N.A., Edme, S.J., Tobias, C.M. 2020. Gene expression and physiological differences in neo-octoploid switchgrass subjected to drought stress. BioEnergy Research. 13:63-78. https://doi.org/10.1007/s12155-020-10092-0.