Location: Nematology LaboratoryTitle: Root-knot nematodes in golf course greens of the western United States Author
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2011
Publication Date: 5/1/2012
Citation: McClure, M.A., Nischwitz, C., Skantar, A.M., Schmitt, M.E., Subbotin, S.A. 2012. Root-knot nematodes in golf course greens of the western United States. Plant Disease. 96(5):635-647. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plant roots and cause an estimated ten billion dollars of crop loss each year in the United States and 100 billion dollars globally. Root-knot nematode (RKN) species are parasitic on a wide range of host plants, including alfalfa, turfgrasses, and numerous other crops. The anatomical features of many RKNs are similar, confounding accurate species identification. In this study, an ARS scientist and colleagues from Arizona, California, and Utah used DNA markers to identify and establish relationships among dozens of RKN populations that were isolated from turfgrass throughout the western United States, and developed a molecular test to discriminate two closely related species. This research is significant because new molecular information obtained for these populations will facilitate future identification of RKN. This report will aid researchers and diagnosticians in accurately identifying economically important root-knot nematodes that are difficult to tell apart by comparing anatomical features alone.
Technical Abstract: A survey of 238 golf courses in ten of the Western U.S. found root-knot nematodes (Meloidogyne spp.) in 60 % of the putting greens sampled. Sequence and phylogenetic analyses of 18S rRNA, D2-D3 of 28S rRNA, ITS-rRNA and mtDNA gene sequences were used to identify specimens from 110 golf courses. The most common species, M. naasi, was found in 58 golf courses, distributed from Southern California to Washington, in the coastal and/or cooler areas of those states. In the warmer regions of the Southwest, M. marylandi was recovered from 38 golf courses, and M. graminis from 11 golf courses. This constitutes the first report of M. marylandi in Arizona, California, Hawaii, Nevada, and Utah, and the first report of M. graminis in Arizona, Hawaii, and Nevada. Two golf courses in Washington were infested with M. minor, the first record of this nematode in the Western Hemisphere. Columbia root-knot nematode was found in a single golf course in California. PCR RFLP of the intergenic region between the cytochrome oxidase and 16S rRNA genes in the mitochondrial genome with restriction enzyme SspI was able to distinguish populations of M. graminis from M. marylandi, providing a fast and inexpensive method for future diagnosis of these nematodes from turf.