Submitted to: Western Society of Weed Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2001
Publication Date: N/A
Technical Abstract: Yellow Starthistle (Centaurea solstitialis) has been recognized since the 1920s as noxious weed in the Pacific Northwest. Infestations are estimated at over 8 million acre, primarily in California, Oregon, Washington, Idaho, with smaller populations in Nevada, Arizona, Utah and New Mexico are currently infested with yellow starthistle. Yellow Starthistle invades rangeland, pastures and roadsides, competes with native plant communities, and reduces biological diversity and the value of grazing land . As an annual, yellow starthistle relies exclusively on seeds for reproduction, nearly all of which are produced by outcrossing. Rangeland plants may average 10,000 to 40,000 seeds per m2, most of which germinates or is lost to predation or decay within three years. We propose to develop a new strategy for the control of Yellow Starthistle based on a genetic system developed to prevent the spread of transgenes from crops to wild relatives. .We call this strategy the Seed Arrest System (SAS). The basic concept is similar to the use of sterile males in the biological control of insect pest populations. Our proposal is to produce transgenic starthistle plants that contain a controllable gene system that will, when activated by chemical treatment of seed, grow to normal size and appearance. The plants however will not produce seed but will produce pollen that carries a seed development arrest gene. This pollen competes with non transgenic pollen in fertilization of wild starthistle flowers. Flowers fertilized with transgenic pollen do not make seed but continue to compete with fertile plants for resources. Thus fertile plants also produce fewer seeds, further decreasing overall seed output, a significant factor for reducing yellow starthistle populations to establish more desirable vegetative cover.