Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 9, 2009
Publication Date: March 17, 2009
Citation: Bushman, B.S. 2009. Improving Stress Tolerance and Yield in Orchardgrass (Dactylis Glomerata). Meeting Abstract. Technical Abstract: Orchardgrass is a forage of choice in irrigated pastures in the western U.S.A. due to its high quality and biomass production. However, orchardgrass periodically suffers from drought and freezing stresses, to a greater extent than some other forage grasses. Additionally, U.S. orchardgrass breeding efforts usually focus on varieties for middle and eastern portions of the country that receive more rainfall. Thus, to improve orchardgrass for the western U.S., the USDA-ARS Forage and Range Research Lab (FRRL) initiated a breeding and improvement program. Orchardgrass breeding populations have been developed for: 1) germplasm with increased yield under irrigation in semi-arid conditions, 2) germplasm with winter-hardiness in locations without snow cover, and 3) semi-hybrid germplasm for potential increased yield. Further studies are underway to develop DNA marker resources in orchardgrass, to and discover the genetic mechanisms of winter-hardiness and flowering time. An EST library was constructed from cold-hardened crowns, salt and drought stressed shoots, and salt and drought stressed roots. Over 15,000 EST unigenes were sequenced from the library, providing 1,200 EST-SSR markers. Most markers showed high homology to ESTs and genes in other grasses and have been assigned putative genetic map positions based on synteny with orthologous genes in rice. A set of 23 SSR markers were used to compare genetic relationships of three cultivars to 15 orchardgrass subspecies. It was found that subspecies lobata was the nearest relative to all three cultivar checks and that within population variation was less in cultivars than it was in subspecies. Future research at the FRRL will continue to focus on developing cultivars for the semi-arid western U.S.A., determining genetic mechanisms responsible for stress tolerance traits and identifying DNA markers associated with stress tolerance genes.