Location: Wheat, Sorghum and Forage Research
2019 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.
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. 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 component has produced steer average daily gains of up to 4 lbs/hd/day. After 20 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 storage, greenhouse gas emissions, and nutrient removal by each crop. Field-scale production of ‘Liberty’ switchgrass, big bluestem, and a low-diversity mixture of big bluestem, indiangrass, and sideoats grama on a marginally-productive site had no clear differences in response to N rate, so lower N rates are being evaluated at the field scale. Perennial grasses grown on marginally-productive cropland in eastern Nebraska can reliably produce 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 Sub-objective 2A, five perennial grass species are being bred for both livestock and bioenergy production systems. The new breeding program maintains parents for 1-2 generations, quantifies the breeding values of both parents and progeny in multi-generational analyses, integrates the pedigree into the prediction process, and assesses the value of including disease traits for rusts and mosaic virus in the selection index. A genomic selection framework using quantitative trait locus mapping, classical genetics, physiology, transcriptomics, and virology is being explored 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 G x E interactions. In Sub-objective 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 maintained into the greenhouse. Greenhouse crosses have been initiated. In Sub-objective 2C, greenhouse and field studies were initiated to develop crosses between tetraploid and octoploid switchgrass to transfer genes for adaptation and yield and increase genetic diversity. Ramets were collected from the field, planted into pots, and maintained in the greenhouse to initiate greenhouse crosses. Data collected from field-grown plants are being analyzed to extract the same information. In Sub-objective 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. In Sub-objective 2E, triticale lines were visually evaluated. However, early-season evaluation was delayed due to furlough. Plant yield has been collected and will be analyzed to identify candidate lines.
Objective 3: The research goal is to identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production to improve breeding and management. Field and lab work are in progress. Leaves will be collected at regular intervals from field-grown big bluestem and switchgrass plants during growing season. Leaves will be extracted for RNA and protein to validate experimental protocols required for FY20 growing season. Internodes will be collected from 12 parent plants in late August 2019 and November 2019 to develop baseline data about the parent plants. Available RNA-Seq data are being mined to develop foundational information about gene expression in two switchgrass cultivars of importance to the ARS breeding program. A preliminary manuscript analyzing gene-expression profiles over leaf development in the contrasting switchgrass cultivars has been submitted to a peer-reviewed journal.
Accomplishments
1. Specific genes control adaptation in switchgrass. Understanding how specific genes interact with the environment is critical to breeding improved crops for agricultural production. A research team including ARS scientists in Lincoln, Nebraska, mapped genes for four switchgrass populations across 10 sites ranging from Texas to South Dakota. We demonstrated that most genes that control locally adaptive traits are beneficial in some environments but have little or no detectable cost in other parts of the geographic range of switchgrass. Consequently, genes that contribute to local adaptation vary in the degree to which they are costly in alternative environments but typically result in greater benefits than costs. As a result, locally advantageous alleles could be combined to breed new high-yielding locally adapted switchgrass varieties.
Review Publications
Fielder, J.D., Lanzatella, C., Edme, S.J., Palmer, N.A., Sarath, G., Mitchell, R., Tobias, C.M. 2018. Genomic prediction accuracy for switchgrass traits related to bioenergy within differentiated populations. Biomed Central (BMC) Plant Biology. 18:142. doi.org/10.1186/s12870-018-1360-z.
Varsani, S., Zhou, S., Koch, K.G., Williams, W.P., Heng-Moss, T., Sarath, G., Luthe, D., Jander, G., Louis, J. 2019. 12-Oxo-phytodienoic acid acts as a regulator of maize defense against corn leaf aphid. Plant Physiology. 179:1402-1415. https://doi.org/10.1104/pp.18.01472.
Guptar, A.K., Scully, E.D., Palmer, N.A., Geib, S.M., Sarath, G., Hein, G.L., Tatineni, S. 2019. Wheat streak mosaic virus alters the transcriptome of its vector, wheat curl mite (Aceria tosichella Keifer), to enhance mite development and population expansion. Journal of General Virology. 100(5):889-910. https://doi.org/10.1099/jgv.0.001256.
