Submitted to: Meeting Abstract
Publication Type: Popular Publication
Publication Acceptance Date: July 21, 2009
Publication Date: August 13, 2009
Citation: Haudenshield, J.S., Hartman, G.L. 2009. Utilization of Molecular Detection Techniques to Find Soybean Pathogens [abstract]. Agronomy Day Brochure, August 13, 2009 , Champaign, IL. 2009:7. Technical Abstract: Soybeans continue to rise in prominence as a source of feed, food, oil, and renewable energy. Of many factors impacting yield, microbial pathogens alone can cause significant losses in production. Management of soybean diseases and pests involves many approaches including cultural aspects like crop rotation, tillage practices and cultivar or variety selection. Other management practices include pesticide applications of fungicides or insecticides to the surface of seed or on plant foliage for protection from disease and pest organisms. Both field diagnosis (for immediate disease control) and research on disease epidimeology and management, inherently require a method of detecting and quantifying the presence of the pathogen responsible. Traditional methods often require highly skilled diagnosticians, animal-based antibodies, lenghthy grow-out or culturing procedures, laboratory equipment and methods unique to each pathogen (nematodes, fungi, etc.), and tissue fixation and microscopic evaluation or even electron microscopic analysis. Recent advances in molecular biology, however, now permit identification and quantification based on the presence of the pathogen DNA. The amount of pathogen DNA present is directly proportional to the number of pathogen cells present, which in turn is proportional to the mass of mycleium, the number of fungal spores, bacteria, or protozoa, or the quantity of virus. Because DNA is fundamental to all life, and yet the primary structure of the DNA is unique to every species, it is possible to employ a streamlined procedure to isolate the DNA from infected plant specimens (or infested soil), and then to utilize a common type of molecular assay (Q-PCR) to determine the precise identity and quantity of pathogen present. Q-PCR assays are already available for pathogens causing many soybean diseases, including: anthracnose, charcoal rot, sudden death syndrome, soybean rust, phytophthora root and stem rot, brown stem rot, and soybean cyst nematode. New and/or improved assays are being continually reported. The soybean disease laboratory at the National Soybean Research Center has developed or is in the process of developing Q-PCR assay for the major soybean diseases.