2012 Annual Report
1a.Objectives (from AD-416):
Identify, characterize, and develop grass germplasm suitable for turf uses with improved heat tolerance, disease tolerance, drought tolerance, water-use efficiency, and salt tolerance using conventional and molecular methods to improve the germplasm enhancement process. Emphasis will be placed on heat tolerance and disease resistance through the period of this project plan. Identify molecular markers and construct linkage maps of bentgrass (Agrostis spp.) that identify regions that impact heat tolerance. Work will also be conducted through cooperative agreements on low maintenance turfgrass species such as Koeleriamacrantha and Danthoniaspicata. Identify genetic markers for bentgrass foliar disease resistance to (dollar spot) and use them to select highly resistant Agrostisgermplams. Construct comparative maps to align genomes of selected forage and turf plants with cereal food crops and utilize this information to improve grass genetic resources.
1b.Approach (from AD-416):
Collect germplasm from natural grasslands worldwide of species having potential as turfgrasses; collaborate with forage, rangeland, and turfgrass scientists to identify, locate and collect germplasm. Study establishment, persistence, survival under different management strategies, and resistance to pests and diseases. Determine presence of endophytes, and whether endophytes affect resistance to pests, diseases, or environmental stresses. Examine physiology under different stresses and inputs to determine genetic mechanisms of resistance to biotic and abiotic stresses. Develop molecular markers from segregating populations, to allow introgression of desirable genes into germplasm with other valuable traits. Identify and isolate genes for resistance to pests and pathogens for potential genetic engineering of adapted selections. Create intra-specific, inter-specific, and inter-generic hybrids with superior turfgrass characteristics.
Chromosomal regions in bentgrass that influence heat tolerance have been determined to be primarily located in species other than creeping bentgrass, the primary cultivated bentgrass species. In order to effectively transfer heat tolerance traits from related bentgrass species, a crossing program and cytogenetic chromosome pairing studies have been initiated to determine the most effective method for transferring desirable traits from one bentgrass species to another.
Interspecies crossing experiments have been established to transfer improved Sclerotina resistance from bentgrass germplasm into the cultivated creeping bentgrass. A total of 34 wide hybridizations were established and progeny will be screened to determine if they are the result of a successful interspecific hybridization or a self-fertilization. Hybrid progeny will be screened for Sclerotinia resistance and backcrossed to cultivated creeping bentgrass to improve overall turf quality while retaining Sclerotinia resistance.
ARS researchers in Beltsville, MD are working with a native grass species Danthonia spicata (Poverty oatgrass) that is drought tolerant and persists well in low pH, high iron soils commonly found on the east coast of the U.S. Poverty oatgrass has a symbiotic association with a fungal species that may contribute to its ability to tolerate severe abiotic stresses such as drought and poor soil fertility. Research is being conducted to develop a better understanding of the reproductive biology and unique stress tolerance mechanisms of this grass.
Diploid bentgrass diversity. Creeping bentgrass is an important turfgrass species often grown on golf courses in regions of the U.S. where it is adapted. Important breeding objectives for creeping bentgrass are improved heat and drought tolerance and resistance to common turfgrass diseases such as dollar spot. ARS researchers in Beltsville, MD evaluated Diploid germplasm to identify plant material closely related to the cultivated polyploidy creeping bentgrass. The diversity analysis of 181 diploid bentgrass selections identified five subpopulations with nine selections being genetically similar to cultivated creeping bentgrass. This improved understanding of the potential progenitors of cultivated creeping bentgrass may help breeders transfer important stress tolerance traits to the cultivated gene pool.
Amundsen, K.L., Rotter, D., Jung, G., Belanger, F., Warnke, S.E. 2012. Miniature inverted-repeat transposable element identification and genetic marker development in Agrostis. Crop Science. 51:854-861.
Amundsen, K.L., Warnke, S.E. 2012. Species relationships in the genus Agrostis based on flow cytometry and MITE-display molecular markers. Crop Science. 51:1224-1231.