Location: Forage Seed and Cereal Research2011 Annual Report
1a. Objectives (from AD-416)
Provide the seed industry with improved grass germplasm and management practices that reduce the impact of salinity, weeds, and diseases on seed quality and profitability. Identify bioactive compounds and genes that mediate the response of Lolium and Festuca to salinity related stress. Develop approaches to characterize, select and utilize components of host genetic resistance to pathotypes of the stem rust pathogen in Lolium. Determine whether a small molecular weight bioherbicide, produced by selected naturally occurring soil rhizobacteria (Pseudomonas sp.), that inhibits the germination of Poa annua can reduce the impact of this weed on seed production and turf quality. Develop molecular methods and tools that facilitate germplasm improvement for diverse uses. Develop a means to improve gene stability and minimize escape of transgenes in forage and turf grasses (Lolium sp.). Characterize genetics of host resistance to stem rust, and develop molecular markers for stem rust resistance in Lolium. Identify candidate genes that can be exploited to increase biomass of cool-season grass plants (Lolium sp.) to improve forage quality and source material for bioenergy production.
1b. Approach (from AD-416)
Conduct complex basic and applied research to improve the production and utilization of seed and grain from forage and turf seed cropping systems which include wheat. Traditional breeding and molecular genetics will be used to identify the genetic basis for stem rust resistance, factors that impact seed quality, flowering, and abiotic stress tolerance. Develop molecular and traditional approaches useful for altering plant developmental pathways and plant structures, and enhancing forage quality in end-use environments that differ from the seed-producing region. Bioherbicides that reduce weed presence in seed production and turf environments will be identified and characterized to enable commercialization of new products.
3. Progress Report
Progress was made on both objectives and their subobjectives which fall under National Program 215, Component 2, Pasture Management Systems to Improve Economic Viability and Enhance the Environment, Component 3, Sustained Harvested Forage Systems for Livestock, Bioenergy and Bioproducts, and Component 4, Turf Plant Materials. Progress on this project focuses on Problem D, the need for appropriate plant materials to improve economic viability and enhance the environment in pasture-based livestock systems, Problem H, the need for improved plant materials that enhance the environment while improving the economic viability of harvesting and using grasses and forage legumes for livestock, bioenergy and bioproducts, Problem J, the need for improved management practices that enhance the environment and increase the economic viability of growing, harvesting, and storing forage grass and lebumes for bioenergy and byproduct systems, and Problem K., the need for improved germplasm that is adapted to biotic and abiotic stresses and meets the economic and environmental objectives of turf producers and users. Under Objective D.2, we made significant progress by sequencing the complete genome of the strain of Pseudomonas fluorescens that secretes a germination arrest factor (GAF) with herbicidal activities against an array of grassy weeds. This sequence information permits direct comparison of gene sequences in closely related strains of the bacterium that do not produce GAF, enabling us to understand how GAF production is regulated. Under Objective H.2, we made progress by introducing genes encoding proteins that have potential to enhance yield and quality into model grass species and are currently assessing their effects. To address Objective J.1., we successfully operated a farm-scale gasification unit that produced a medium heating value syngas, and used the syngas to supplement diesel fuel required to fuel a generator. Significant progress was made in addressing Objective K.1 by our success in demonstrating an approach to disrupt specific gene function in forage and turf grass species through virus-induced-gene-silencing, and by the development of an in-house transformation system for Lolium. We also established the foundation for further progress in developing genetic resistance to stem rust by completing a genetic map for perennial ryegrass by adding an additional type of genetic marker to our preliminary map. The map was used to locate regions of the genome associated with quantitative resistance to stem rust on chromosomes 1, 6 and 7.
1. Bioherbicide identified. Grassy weeds present a constant problem for agriculture that affects the yield and productivity of many crops throughout the US. Germination arrest factor (GAF) is a naturally occurring bioherbicide that was found to irreversibly arrest germination of the seeds of grassy weeds, such as annual bluegrass (Poa annua), without significantly affecting the growth of established grass seedlings and mature plants or germination of the seeds of broadleaf plant species (dicots). The specific compound responsible for this inhibition of germination was isolated and identified by ARS scientists in Corvallis, Oregon, and Oregon State University collaborators. The structural analysis of the compound is the first step toward the potential commercialization of this bioherbicide to control grassy weeds in agricultural production systems, a measure that will decrease inputs and increase yield of crops.
2. Grasses respond to wounding. Grasses are continually cut for hay and grazed by livestock, however very little is known concerning the molecular events that occur in grass plants as a result of wounding. ARS scientists in Corvallis, Oregon, identified a signal that activated a signaling protein in response to wounding in certain forage and turf grasses. The activation of this signaling protein occurs very rapidly, within 2-3 minutes of wounding, and this wound signal is transmitted to distant unwounded portions of the plant within 5 minutes. This is the first report of a systemic wound signal being transmitted from one tiller to an adjacent tiller through the root crown in grasses. This finding is a critical first step towards understanding how to improve and increase yields, sustainability and quality of grass feed stocks utilized for livestock and for biofuel production after wounding or when environmental stresses are present.
Kimbrel, J.A., Givan, S.A., Halgren, A.B., Creason, A.L., Mills, D.I., Banowetz, G.M., Armstrong, D.J., Chang, J.H. 2010. An Improved, High-Quality Draft Genome Sequence of the Germination-Arrest Factor-Producing Pseudomonas fluorescens WH6. Biomed Central (BMC) Genomics. 11:522-536.