2011 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.
Field and greenhouse data from 2008 and 2009 was used to search for chromosome locations influencing drought and heat tolerance in Bentgrass. The analysis identified several important chromosomal regions governing stress tolerance traits in Bentgrass species. The importance of these chromosomes in tolerance to multiple stresses may be most useful in future studies for the development of marker assisted selection for both heat and drought tolerant creeping bentgrasss cultivars.
Sclerotinia resistance screening. Plant tissue of creeping bentgrass inoculated with both Sclerotinia homoeocarpa and Rhizoctonia solani was collected and is being prepared for study using high throughput DNA sequencing. Gene expression differences that occur during infection may provide clues to the methods of resistance to these two important turfgrass pathogens. The goal of this work is to develop more efficient methods of selecting disease resistant grass that will lead to a reduction in fungicide applications to turfgrasses.
Agrostis genetic diversity. Newly developed genetic markers were used to study the genetic diversity of both diploid and tetraploid creeping bentgrass germplasm. The analysis with these markers identified important relationships between bentgrass species and will allow us to develop crossing strategies to transfer important traits such as heat and drought resistance and disease resistance from closely related bentgrass germplasm. The analysis indicates that during the process of creeping bentgrass cultivar development, significant reductions in genetic diversity have occurred. Reduced genetic diversity can lead to critical crop vulnerabilities to disease and stress that could result in sudden crop losses. Knowledge gained from this research will be used to enhance the genetic diversity of creeping bentgrass.
Genetic diversity of bentgrass. ARS scientists in Beltsville, MD used DNA technologies to develop an improved understanding of the genetic diversity of bentgrasses. Bentgrasses are an important group of turfgrasses widely used on golf courses throughout the world. Bentgrasses are highly diverse; however, during the process of cultivar development much of the genetic diversity present in the species can be lost. New DNA marker technologies were used to understand the relationships between bentgrass species and to develop new strategies for transferring important stress tolerance genes between species to reduce golf course inputs and develop more sustainable turfgrass management practices.