2013 Annual Report
1a.Objectives (from AD-416):
Objective 1: Develop and evaluate improved grass germplasm for the southern U.S. that is more productive, biologically diverse, tolerant of biotic and abiotic stresses, improved in quality, and easier to establish and maintain in pastures and rural landscapes.
Sub-objective 1.A: Develop and evaluate kleingrass (Panicum coloratum) germplasm with improved forage yield, seedling vigor, and persistence.
Sub-objective 1.B: Produce intraspecific Paspalum hybrids between different dallisgrass biotypes to develop improved forage types.
Sub-objective 1.C: Identify superior Texas bluegrass (Poa arachnifera) genotypes that are rust resistant and adapted to the humid southeastern U.S. to develop a synthetic population from these genotypes.
Objective 2: Use genomic techniques to develop and identify molecular markers associated with traits of interest in forage and turf grasses.
Sub-objective 2.A: Identify molecular markers to further saturate the genomic region controlling apomixis and survey candidate genes for seed sterility in buffelgrass (Pennisetum ciliare).
Sub-objective 2.B: Develop a genetic map of dallisgrass (Paspalum dilatatum) to identify markers linked to apomixis, disease and insect resistance, and other traits of interest.
Objective 3: Develop improved breeding methodologies by determining the cytology, reproductive biology, and genetic diversity of native and introduced germplasm for the production of improved forage and turf grasses.
Sub-objective 3.A: Determine the method of pollination, chromosome number, ploidy level, and mode of reproduction of species in the genera Panicum, Paspalum, Pennisetum, Sorghum, Chloris, Setaria, Stenotaphrum, Tripsacum, and others to facilitate their genetic improvement.
Sub-objective 3.B: Determine the genetic diversity and phylogeny of Paspalum and Pennisetum species using DNA fingerprinting techniques.
1b.Approach (from AD-416):
The long-term objectives of this project are to obtain a better understanding of the cytology, reproductive biology, and genetic diversity of selected forage grasses, and to use this fundamental information in the breeding and development of superior germplasm that will be released as improved cultivars.
Project work in FY 2013 focused on development of a new kleingrass germplasm line and its evaluation in several different geographic areas. Significant progress was made in development of additional kleingrass germplasm lines for evaluation as improved livestock forage grasses for southeastern U.S. environments. During the life of this project, significant advances were made in the development and selection of superior germplasm that will be used as improved forage grasses. Working in collaboration with Texas A&M University and Louisiana State University scientists, a new dallisgrass cultivar was released to provide livestock producers in the southeastern U.S. with a more productive and more persistent option to common dallisgrass. Twenty-four superior Texas bluegrass genetic types were selected from a field nursery in Louisiana, and these were used to develop a new bluegrass line that is adapted to the humid southeastern U.S. Using modern research techniques, the chromosome number was determined for 568 buffelgrass accessions in the National Plant Germplasm System buffelgrass collection, and this information was entered into the Germplasm Information Resources Network to provide information to plant breeders throughout the world as to how to utilize the germplasm in hybridization programs. In collaborative research with Texas A&M University scientists, analyses of the chromosome pairing behavior and the chromosome composition of Sorghum bicolor x S. macrospermum first generation (F1) and subsequent backcross hybrids determined the amount of genetic intermixing (introgression) that occurs between the chromosomes of the two species. The data showed that important genes, such as for disease and insect resistance, can be transferred from wild sorghum species into S. bicolor (commercial grain sorghum). This work established that the iap (Inhibition of Alien Pollen) genetic component (allele) in S. bicolor allowed the pollen from other grass genera to fertilize S. bicolor. Thus, the iap allele allows the transfer of exotic genes into commercial sorghums which increases the genetic diversity of the species. Genetic tools known as molecular markers (specifically SSRs) were used with other appropriate techniques to determine the origin of suspected perennial sorghum hybrids that were growing in the wild. Some hybrids originated from natural crosses between S. bicolor and S. halepense, and others were derivatives from natural backcrosses between S. halepense and S. bicolor x S. halepense hybrids. These markers made it possible to verify interspecific sorghum hybrids and quantify natural gene flow between sorghum species. This project expired in FY 2013, but was replaced by 6202-21000-033-00D which is expanding upon the work of the precursor project.
Perennial biomass sorghums. Although essentially all sorghum types grown for biomass production are annuals in temperate environments, there would be potentially great economic advantages if biomass sorghums were perennial. An appropriate approach for developing perennial biomass sorghums is to transfer genes controlling rhizome development from different rhizomatous Sorghum species to S. bicolor using the genetic technique known as interspecific hybridization. ARS scientists at College Station, Texas, in collaboration with Texas A&M University scientists, used modern genetic techniques to identify candidate genes from rhizomatous sorghums that could be used to convert annual sorghums into perennial sorghums having good biomass potential. The ultimate development of high biomass perennial sorghums should be of high value to the alternative energy industry and should offer good profit potential to producers. An added benefit is that perennial sorghums would likely overwinter successfully in colder climates and could be grown as a dual-purpose crop for both bioenergy production and forage.
Washburn, J.D., Whitmire, D.K., Murray, S.C., Burson, B.L., Wickersham, T.A., Heitholt, J.J., Jessup, R.W. 2013. Estimation of rhizome composition and overwintering ability in perennial Sorghum spp. using near-infrared spectroscopy (NIRS). BioEnergy Research. 6:822-829.
Dowling, C.D., Burson, B.L., Foster, J.L., Tarpley, L., Jessup, R.W. 2013. Confirmation of pearl millet-napiergrass hybrids using EST-derived Simple Sequence Repeat (SSR) markers. American Journal of Plant Sciences. 4:1004-1012.
Kiniry, J.R., Johnson, M., Venuto, B.C., Burson, B.L. 2013. Novel application of ALMANAC: Modelling a functional group, exotic warm-season perennial grasses. American Journal of Experimental Agriculture. 3(3):631-650.