2012 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.
During FY 2012, research under this project continued to make advances in developing, selecting, and evaluating superior grass germplasm for the purpose of developing improved forage grass cultivars. Data from kleingrass (Panicum coloratum) forage evaluation plots at Beeville, College Station, San Angelo, and Stephenville, TX, will establish if a new synthetic line is more productive and better adapted than commercially available kleingrass cultivars. More than 600 kleingrass seedlings from seed that was collected from a kleingrass polycross block were established in a field nursery to identify the superior genotypes that will be used to produce additional synthetic lines. In a cooperative study with Texas A&M University scientists to develop perennial sorghum plants that will be used as bioenergy feedstocks, the relationship between winter hardiness and different metabolites in the rhizomes of robust Johnsongrass (Sorghum halepense) genotypes was investigated. It was determined that water soluble carbohydrates, ethanol soluble carbohydrates, and the concentrations of fructans in the rhizomes are positively correlated to over-wintering, while starch and crude fat concentrations are negatively correlated to over-wintering. With the exception of crude fat concentrations, methods were developed using infrared spectroscopy (NIRS) to quickly and effectively predict the concentrations of each of these metabolites within rhizome tissue. This information can be used to screen rhizomatous sorghum species and predict their ability to survive winters in Texas. Buffelgrass genotypes with high and low seed fertility were identified and a set of molecular tools known as EST-SSR markers were developed in an effort to identify genes for seed sterility in the species. Appropriate analysis of these markers is underway.
Molecular characterization of wild perennial sorghum hybrids. Sorghum offers great potential as a biomass crop for biofuel production. New, more biomass-productive sorghum types are necessary if sorghum is to realize its full potential in bioenergy production. ARS scientists at College Station, Texas, working with researchers at Texas A&M University, developed modern molecular biology tools to characterize different types of sorghums, including hybrid species. The work showed that the tools (known as molecular markers) can be applied effectively in research on sorghum to more quickly identify/develop better sorghum types for cultivation as feedstocks for biofuel production.
Chromosome numbers of buffelgrass lines. The ability of closely related grass lines to interbreed is greatly influenced by their chromosome number, with lines of equal chromosome number having the greatest fertility. ARS scientists at College Station, Texas, used modern molecular biology tools to determine the chromosome numbers of 568 buffelgrass (Pennisetum ciliare) lines. About half of the lines had 36 chromosomes, but others had 45, 54, and even 63 chromosomes. This work has documented the great chromosomal diversity that occurs in the National Plant Germplasm System buffelgrass collection; relevant data obtained by the work has been entered into the Germplasm Information Resources Network (GRIN) database, where it is readily available and will be of great value to breeders in their work to improve the agronomic traits and forage value of buffelgrass.
Jessup, R.W., Whitmire, D.K., Burson, B.L. 2012. Molecular characterization of non-flowering perennial Sorghum spp. hybrids. American Journal of Experimental Agriculture. 2(1):9-20.
Burson, B.L., Actkinson, J., Jessup, R.W., Hussey, M.A. 2012. Ploidy determination of buffel grass accessions in the USDA National Plant Germplasm System collection by flow cytometry. South African Journal of Botany. 79:91-95.
Bartek, M.S., Hodnett, G.L., Burson, B.L., Stelly, D.M., Rooney, W.L. 2012. Pollen tube growth after intergeneric pollinations of iap-homozygous Sorghum. Crop Science. 52:1553-1560.