Location: Floral and Nursery Plants Research2013 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.
3. Progress Report:
This is the final report for this project which terminated 2/5/13 and will be replaced by new project 1230-21000-065-00D. Substantial results were realized over the life of this project. Creeping bentgrass (Agrostis stolonifera L.) is the premier turfgrass species used on golf course putting greens, fairways, and tees. One of the difficulties in determining the progenitors of the cultivated bentgrasses is the lack of accurate ploidy determinations for many of the Agrostis accessions maintained in the National Plant Germplasm System (NPGS). ARS scientists working in Beltsville, MD analyzed 75 Agrostis accessions representing 15 distinct species along with two Apera and four Polypogon accessions using flow cytometry and 1,309 DNA markers. Cluster analysis clearly separated the common turf-type Agrostis species into distinct groups. The inclusion of previously understudied species within these groups offers insights into the genomic origins of creeping bentgrass that will be useful in future breeding efforts. In addition, the data suggest a narrowing of the genetic diverstiy within cultivated creeping bentgrasses. The turfgrass diseases dollar spot and brown patch, caused by the fungi Sclerotinia homoeocarpa and Rhizoctonia solani, are the most widespread fungal diseases of highly managed turfgrass species such as Creeping bentgrass (A. stolonifera). More money is spent to manage these diseases than all other turfgrass diseases combined. Dollar spot and brown patch are widespread during the summer months in warm humid areas of the United States, and spray programs are generally scheduled at regular intervals to safeguard against disease establishment. However, these spray strategies can lead to the fungi developing fungicide resistance and this has become a major issue in certain regions of the county. ARS researchers at Beltsville, MD are using new high throughput DNA sequencing technologies to determine the genes that are important in the interaction of these important fungal pathogens with turfgrass plants. In order to establish a better understanding of the location of genes that influence dollar spot resistance, two experimental mapping populations were developed and genetic linkage maps created. An experimental mapping population was developed at Rutgers University by crossing a resistant creeping bentgrass plant to a susceptible creeping bentgrass plant. AFLP and SSR genetic markers were then used to develop a linkage map of this population and determine the location of genome regions influencing dollar spot resistance. A second experimental mapping population was also developed at Rutgers that involves a cross between resistant colonial bentgrass and susceptible creeping bentgrass. AFLP markers were also used to develop a linkage map of this cross for determining the genome location of resistance genes. In the future it may be possible to utilize genetic markers for the selection of dollar spot resistance which would dramatically speed up the development of dollar spot resistant creeping bentgrass germplasm and lead to a significant reduction in golf course fungicide applications.