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United States Department of Agriculture

Agricultural Research Service


item Kroop Bradley R
item Albee Steve
item Flint Karen M
item Zambino Paul
item Szabo, Les
item Thomson Sherman

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Since the introduction of Dyers woad into the United States, it has become a serious problem in western rangelands where this noxious weed is spreading rapidly. Dyers woad is well suited to growth on the dry rocky soils found throughout much of the Intermountain West and as a result it is a threat to native plant communities. Control of dyers woad through conventional means is not feasible due to the rugged and often remote areas in which it grows. However, the use of a natural fungal pathogen (Puccinia thlaspeos) may provide an economical and practical solution. The development of this biocontrol agent has been hindered by the long latent period, of up to a year, in the infection process. We have developed a method for the early detection of this rust fungus, based on a set of primers (short segments of DNA) that are specific to Puccinia. This method allows the detection of a specific segment of DNA in this fungus by amplifying this segment up to a million-fold. This amplification process is called polymerase chain reaction (PCR). This development will benefit both scientists studying this fungal disease, as well as others doing basic work on this group of rust fungi.

Technical Abstract: Rust-specific PCR primers selectively amplified ribosomal DNA of a rust fungus (Puccinia thlaspeos) from infected dyers woad. PCR enabled DNA of the fungus to be detected in symptomatic plants as well as in asymptomatic parts of diseased plants. The use of PCR enabled early detection of rust infections in dyers woad plants during the first season when they are often asymptomatic. Dried plant samples stored at room temperature for several months worked at least as well as lyophilized material for DNA extraction prior to PCR. This PCR-based detection method should facilitate further studies on the biology and artificial infection of this and other systemic rusts which have potential for use in biocontrol of weeds.

Last Modified: 06/24/2017
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