Progress 05/01/99 to 04/30/05
Outputs
We have continued to add DNA sequence of plant feeding nematodes to GenBank, including regulated and unregulated species. Many of these accessions are linked to voucher web pages we have generated and linked to GenBank through the Linkout function. We are continually testing and validating sequence based nematode identifications.
Impacts
By incorporating molecular identification techniques into a regional potato survey, we were able to determine that root-knot nematodes recovered as infective juveniles in the soil were not regulated potato pests. Therefore those potato growers are elgible to receive phytosanitary certification allowing access to international markets.
Publications
- Mullin, P.G., T.S. Harris, and T.O.Powers. 2005. Phylogenetic relationships of Nygolimina and Dorylaimina (Nematoda: Dorylaimida) inferred using small subunit ribosomal DNA. Nematology 7:59-79.
- Powers, T.O. P.G. Mullin, T.S. Harris, L. A. Sutton, and R.S. Higgins. 2005 Incorporating molecular identification into a large-scale regional nematode survey. Journal of Nematology. 37:226-235.
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Progress 10/01/03 to 09/30/04
Outputs
We have continued to add nematode sequences to GenBank. This year we emphasized validation and voucher documentation of submitted sequences. We worked closely with Scott Federhen at NCBI/NIH to design specific "link-out" pages that accompany GenBank DNA accession numbers. We have also conducted a molecular diagnostic workshop in Mexico City September 29-October 1st that included quarantine officials from numerous Latin American countries. Continued correspondence with paticipants by email has helped others adopt diagnostic protocols. We have accumulated new nematode species that require genetic characterization.
Impacts
Our nematode database is the largest in existance that includes digital photographs and collateral information about the specimens.It is useful for rapid identification of pest nematodes and for understanding the performance of the different diagnostic markers used for identification.
Publications
- Neher, D.A. and Powers, T.O. 2004. Nematodes. In: Hillel, D., Rosenzweig, C., Powlson, D., Scow, K., Singer, M. and Sparks, D. (editors) Encyclopedia of Soils in the Environment, Academic Press, New York. Pg. 1-6.
- Brito, J., T.O.Powers, P.G.Mullin, R.N.Inserra, and D.W.Dickson. 2004. Morphological and molecular characterization of Meloidogyne mayaguensis isolates from Florida. Journal of Nematology. 36: 232-240.
- Duncan,G.A., P.H. Adler, K.P. Pruess, and T.O.Powers. 2004. Molecular differentiation of two sibling species of the black fly Simulium vittatum (Diptera: Simuliidae), based on randomly amplified polymorphic DNA. Genome 47(2) 373-380.
- Powers, T.O. 2004. Nematode molecular diagnostics: From bands to barcodes. Annual Review of Phytopatology. 42:367-385 .
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Progress 10/01/02 to 09/30/03
Outputs
This past year we have added numerous sequences to our nematode sequence databases. There are now over 250 edited partial 18S rDNA sequences representative of nematodes from North America. This database includes all species recovered from Konza Prairie, plant-feeding and free-living, present in 0.2% or more of samples (8,400 nematodes examined). Many species are represented by more than a single sampling location. The mitochodrial and ITS1 databases have also been constructed with an emphasis on Meloidogyne and other regulated pest species found in North America. With regard to quarantine nematodes, we are continuing to screen tubers and soil samples for nematodes that prevent exportation of potatoes. This has included examination of shipments rejected based on the presence of regulated pest species. Twice we have examined rejected potato shipments including potatoes from their respective storage bins and field soil samples, and not found nematodes of regulatory
status. In September 2003, I participated in a conference with Mexican and U.S. regulatory officials to discuss the identification criteria of regulated nematodes.
Impacts
Our nematode database is the largest in existance that includes digital photographs and collateral information about the specimens.It is useful for rapid identification of pest nematodes and for understanding the performance of the different diagnostic markers used for identification.
Publications
- Brito, J., Powers, T.O., Mullin, P.G., Inserra, R.N., and Dickson, D.W. 2004. Morphological and molecular characterization of Meloidogyne mayaguensis isolates from Florida. Journal of Nematology (accepted).
- Mullin, P.G., Harris, T.S. and Powers, T.O. 2004Systematic status of Campydora (Nematoda: Campydorina) Nematology (in press).
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Progress 10/01/01 to 09/30/02
Outputs
At the Fourth International Congress of Nematology I met with leading regulatory officials from Europe and the UK. We are discussing the development of world-wide standards for nematode identification that include molecular diagnostics. Our laboratory continues to maintain the Plant and Insect Parasitic Nematode web site which includes a considerable amount of information on nematode identification. This is the most active nematode web site on the internet, averaging access by 120 unique (first-time) users daily. This web site includes the official site for the Society of Nematology in which we maintain the SON membership list, job bulletin board, meeting registrations, journal guidelines, NEMA-L discussion group, and other society functions. Another official page is the APHIS sponsored Nematodes of Quarantinable Concern, which presents information regarding the nematode regulatory status. Other additions include a database of nematode descriptions including thousands
of photomicrographs of key morphological features, an updated 50 page web document on nematode techniques, a searchable database of references, and numerous features for extension and teaching. We have initiated a region-wide diagnostic service for identification of nematodes of regulatory concerns (those blacklisted by U.S. trade partners). We are now the only nematode diagnostic lab providing DNA- based tests on a routine basis.
Impacts
Molecular diagnostics permits discrimination between regulated pest species and non-target, morphologically similar species. This discrimination preserves domestic markets when phytocertification is necessary to move agricultural commodities across borders. Conversely, molecular diagnostics provides a high-resolution defense against the unintentional introduction of pathogenic species.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
Our laboratory has created the largest and most comprehensive taxonomic/diagnostic database in nematology. http://nematode.unl.edu. This database consists of hundreds of photographs of individual nematode species arranged by ecosystem and feeding behavior. In addition to photographs, species descriptions, key diagnostic features, and molecular markers are presented. We believe this site will become a valuable resource for ecologists and nematologists alike. We are currently constructing diagnostic keys and illustrated/annotated pages that provide distinctive characteristics of species complexes of morphologically similar important plant parasites. Our laboratory has used this feature to illustrate the difference between The Columbia Root-Knot Nematode, Meloidogyne chitwoodi and other Meloidogyne species. Other important discriminations we have developed include protocols for soybean,sugar beet,and clover cyst nematodes, Pratylenchus (lesion) species, Bursaphelenchus
species (the Pine wilt nematode)and the seed gall and stem nematodes Anguina and Ditylenchus species. Ongoing studies are directed at improving molecular diagnostic assays.
Impacts
Nematode diagnostics is important for both pest management and agricultural trade. Surveys are conducted to determine the extent of nematode infestations. Ongoing surveys have delimited the distribution of Meloidogyne chitwoodi, the Columbia root-knot nematode, an internationally regulated pest of potatoes. Molecular protocols speed up the identification process and provide greater resolution than conventional morphological methods. These molecular assays have allowed us to differentiate species of ditylenchid, heteroderid, and meloidogyne species that are superficially similar to regulated species. This has reduced the number of false positives in nematode identification.
Publications
- Szalanski, A.L., P. G. Mullin, T. S. Harris, and T. O. Powers. 2001. First report of Columbia Root Knot Nematode (Meloidogyne chitwoodi) in potato in Texas. Plant Disease (submitted).
- Powers, T. O. 2001. Seed Gall Nematodes.(in) The Encyclopedia of Plant Pathology. John Wiley and Sons.
- Powers, T. O. 2001. Earcockle.(in) The Encyclopedia of Plant Pathology. John Wiley and Sons.
- Powers, T. O., Szalanski, A. L., Mullin, P. G., Harris, T. S., Bertozzi, T. and Griesbach, J. A. 2001. Identification of seed gall nematodes of agronomic and regulatory concern with PCR-RFLP of ITS1. Journal of Nematology. 33(4) (in press).
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Progress 10/01/99 to 09/30/00
Outputs
Our laboratory has created the largest and most comprehensive taxonomic/diagnostic database in nematology. http://ianrwww.unl.edu/ianr/plntpath/nematode/wormhome.htm. This database consists of hundreds of photographs of individual nematode species arranged by ecosystem and feeding behavior. In addition to photographs, species descriptions, key diagnostic features, and molecular markers are presented. We believe this site will become a valuable resource for ecologists and nematologists alike. We are currently constructing diagnostic colleges that provide distinctive characteristics of species complexes of morphologically similar important plant parasites. Our laboratory has used this feature to illustrate the difference between The Columbia Root-Knot Nematode, Meloidogyne chitwoodi and other Meloidogyne species. Other important discriminations we have developed protocols for include soybean/sugar beet/clover cyst nematodes, Pratylenchus neglectus isolates, and
Bursaphelenchus species (the Pine wilt nematode). Our web site currently receives around 90 unique hits a day, the majority from educational institutions.
Impacts
The species determination, which we have developed and published in electronic form, can save millions of dollars in establishing early detection of important parasitic species Meloidogyne chitwoodi alone can eliminate potato exports to Mexico if it is detected in a state. Currently nine western states are unable to export potatoes to Mexico due to the presence of M. chitwoodi in their state. Early detection in seed pieces may prevent other states from becoming infested.
Publications
- Szalanski, A.L., Taylor, D.B. and P.G.Mullin. 2000. Assessing nuclear and mitochondrial DNA sequence variation in Steinernema (Rhabditida: Steinernematidae). Journal of Nematology 32:229-233.
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Progress 10/01/98 to 09/30/99
Outputs
We are continuing to design and apply molecular diagonostic methods for a wide range of nematodes. These in cyst, root-knot, lesion, sting, lance, spiral, ring, needle, stunt, and seed and gall plant parasitic nematodes. We are also documenting and achiving species using the WWW. Nematode profiles include species descriptions, photographs, and molecular characteristics. Nematode keys are being developed in electronic format. A database is being developed to rapidly provide biogeographic information.
Impacts
The electronic availability of our nematological research will made a large contribution to workers in the field. In particular ecologists and diagnosticians will be able to obtain definitive information about specific nematode species. The development of additional diagnostic methods will increase precision and speed up nematode assays.
Publications
- No publications reported this period
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