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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #35823


item Tooley, Paul
item Garfinkel D J

Submitted to: Molecular Plant Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: DNA that can move inside living cells, or moveable DNA (sometimes referred to as "jumping genes"), is known to exist in plants and animals. Evidence for moveable DNA has been found in the fungus that causes late blight disease of potato. For centuries, the fungus, Phytophthora infestans, has eluded attempts to control it, overcoming resistance in potato varieties sometimes within a single season and also becoming tolerant to fungicides applied to control the disease. The fungus first gained notoriety by causing the Irish potato famine in the mid-1800's and since then has been perhaps the most destructive potato disease worldwide. Reasons for the fungus' powerful capacity for rapid genetic change have long been sought. Using a new biological technique for producing large amounts of a specific DNA segment, P. infestans was found to contain segments characteristic of a certain type of moveable DNA. The moveable DNA could be triggered to move within the fungus's chromosome and cause genetic changes to occur. These findings will help scientists understand the ways in which destructive pathogens change and will lead to the development of more effective strategies for control of potato late blight and perhaps other destructive plant diseases

Technical Abstract: DNA sequences related to those present in moveable genetic elements known as retroviruses were identified in the potato blight pathogen, Phytophthora infestans. The sequences were identified by polymerase chain reaction (PCR) amplification of the sequences followed by sequencing of the PCR products. Primers used flanked the active site coding region of the enzyme reverse transcriptase and were specific to retroelements of the Ty1-copia group. PCR products of ca. 280 and 360 bp were amplified from five P. infestans isolates from Mexico and the U.S. using the above primers. PCR products obtained from Mexican isolate 580 and U.S. isolate 176 were cloned and 14 of the products sequenced. The P. infestans sequences showed between 40 and 65 percent similarity with others in the Ty1-copia group. RNA hybridization experiments suggested that the elements are actively transcribed and two major transcripts were observed. The putative retroelement sequences were found to be present in multiple copies within the P. infestans genome, with enough observed polymorphism in hybridization patterns to be potentially useful in pathogen detection, genetic mapping, and population studies