ARS | Publication request: A POLYMERASE CHAIN REACTION ASSAY BASED ON ACTIN GENE SEQUENCES FOR DISTINGUISHING BETWEEN SUGARBEET FUNGAL PATHOGENS

Submitted to: Canadian Journal of Plant Pathology
Publication Type: Abstract Only
Publication Acceptance Date: July 8, 1997
Publication Date: N/A

Technical Abstract: Sugarbeet yield can be reduced significantly due to infection by root, crown and foliar fungal pathogens. For damping off or root rotting diseases, current standard assays involve incubation of diseased tissue to allow proliferation of the pathogen, followed by identification of the pathogen using microscopic techniques. Such techniques can take several days to complete. A more rapid technique based on the polymerase chain reaction (PCR) was developed, therefore, for discriminating between sugarbeet fungal pathogens. Deoxyoligonucleotide primers were designed based on consensus sequences derived from the comparison of fungal actin genes. These primers were used in a PCR- based assay, using genomic DNA of Aphanomyces cochlioides, Rhizoctonia solani Pythium ultimum, Phoma betae, and Cercospora beticola as template. Product DNA amplified in these reactions was polymorphic in size and varied in the number of products amplified in a manner dependant on the organism tested. Sizes for most of the amplified products were consistent with that predicted for the region of the actin gene targeted by the primers. After artificial inoculation of sugarbeet seedlings with Aphanomyces in the greenhouse, the PCR-based assay was able to detect the fungus in surface-sterilized, diseased seedling hypocotyls. The method may lead to a rapid and inexpensive means of distinguishing fugal pathogens of sugarbeet in diseased tissue.