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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR AND MORPHOLOGICAL SYSTEMATICS AND IDENTIFICATION OF IMPORTANT PLANT PARASITIC NEMATODES
2008 Annual Report


1a.Objectives (from AD-416)
1) Discover, refine, and implement improved microscopic, molecular, and software tools to modernize classification and improve predictive features for plant-parasitic and other agriculturally important nematodes; and.
2)Discover new nematode species, new host associations, and new geographic occurrences among the many nematodes sent to the Nematology Laboratory for identification by various customers.


1b.Approach (from AD-416)
1) Adapt and test recently discovered and potentially promising light and scanning electron microscopic methods to determine if visualization of diagnostically important critical features can be improved in resolution and consistency. Characterize new agriculturally important nematodes with expanded or novel morphological and molecular diagnostic characters for the development of improved diagnostic keys and phylogenetic trees. Identify and prioritize, using phylogenetic methods, potential molecular control targets based on physiologically important peptides within diverse nematodes having analogous phenotypes; and.
2)Characterize unknown or important nematodes by morphology, molecular biology and host range; and continue to computerize and curate the USDA Nematode Collection.


3.Progress Report
Identification of Nematodes and New Methods of Identification: The identification of new species of nematodes and the development of new methods to rapidly and accurately identify plant-parasitic nematodes are urgently needed by researchers, regulators, diagnosticians and growers to design the safest, most effective possible plant disease controls. To this end, ARS researchers are describing new species of root-knot, cyst, lesion, and insect-associated nematodes. A new method for recording a diagnostically important structural pattern on the rear surface of the nematode involving a special kind of polarized light microscopy was implemented in the laboratory. When completed, these pest descriptions, their host associations, and the new microscopic methods will be used by diagnosticians and extension personnel throughout the world to accurately diagnose and select appropriate controls for a wide variety of crops.

The USDA Nematode Collection: The researchers and extension personnel that identify nematodes require a source of nematode reference specimens to assure that identifications are accurate. The USDA Nematode Collection at Beltsville, Maryland, is the most important repository of nematode reference specimens in the world. Curatorial services and maintenance are constantly needed to improve the quality and breadth of the Collection. Therefore, scientists at the Nematology Laboratory in Beltsville added 581 slides and vials from worldwide sources to create a total collection of 42,616 slides and vials, loaned 155 slides and vials containing valuable nematode specimens to scientists around the world to enable them to perform accurate nematode identifications, and entered 230 records of specimens into the computerized database, bringing it to a total of 36,175 records. Nematologists throughout the world are using the specimens and related information in the Collection as essential aids in nematode identification and research.

These activities directly address Component 1 (Disease Diagnosis: Detection, Identification and Characterization of Plant Pathogens) of National Program 303 (Plant Diseases); specifically, Problem Statements 1A (New Diagnostic Methods and Tools) and 1B (Detection, Identification, Characterization, and Classification of Pathogens).

See also subordinate Project Number: 1275-22000-250-01R. Title: Identification of Plant-Parasitic Nematodes for Action Agencies, Period Covered from 10/01/2007 to 09/30/2008, for a description of activities related to providing nematode identifications and related information to USDA APHIS.


4.Accomplishments
1. Stunt Nematode Tail Shape Distribution and Molecular Family Tree.

Stunt nematodes are common and important root parasites that seriously damage many economic and ornamental plants worldwide. A major problem with determining the cause of potential crop loss due to these nematodes is delimiting genera and species from one another using prominent characters such as tail shape. In the present study, ARS scientists from Beltsville, Maryland, discovered with anatomical and DNA sequence data that a family tree of stunt nematodes, constructed with original molecular ribosomal DNA sequences of three species plus others from a public database, provided the framework to demonstrate that some tail shapes were similar among genera that greatly differed molecularly. The results are significant because they provide new details important for scientists to more reliably identify species and determine the relationships of different species to each other. This research is expected to be used by scientists, action agencies, and extension agencies for improving the speed of nematode diagnosis and subsequent management recommendations. This accomplishment directly addresses Component 1 (Disease Diagnosis: Detection, Identification and Characterization of Plant Pathogens) of National Program 303 (Plant Diseases); specifically, Problem Statements 1A (New Diagnostic Methods and Tools) and 1B (Detection, Identification, Characterization, and Classification of Pathogens).

2. Discovery of One New and One Known Species of Stunt Nematode on Coconut and Rice.

New, comprehensive information to rapidly and accurately identify plant-parasitic nematodes are urgently needed by researchers, regulators, diagnosticians and growers to deliver the safest, most effective possible plant disease controls. To this end, ARS researchers and international collaborators described stunt nematodes from soil around the roots of coconut and rice using conventional microscopic anatomical features. These detailed descriptions provide the information that allows these species to be identified. This research is expected to be used by scientists, action agencies, and extension agencies for improving the speed of nematode diagnosis and subsequent management recommendations. This research directly addresses Component 1 (Disease Diagnosis: Detection, Identification and Characterization of Plant Pathogens) of National Program 303 (Plant Diseases); specifically, Problem Statements 1A (New Diagnostic Methods and Tools) and 1B (Detection, Identification, Characterization, and Classification of Pathogens).


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

Number of Web Sites Managed1
Number of Non-Peer Reviewed Presentations and Proceedings4
Number of Newspaper Articles and Other Presentations for Non-Science Audiences1
Number of Other Technology Transfer3

Review Publications
Karanastasi, E., Handoo, Z.A., Tzotzakakis, E. 2008. First record of Mesocriconema xenoplax (Nematoda: Criconematidae) in Greece and first record of Viburnum sp. as a possible host for this ring nematode. Helminthologia. 45:103-105.

Smiley, R.W., Yan, G.P., Handoo, Z.A. 2008. First record of the cyst nematode Heterodera filipjevi on wheat in Oregon. Plant Disease. 92(7):1136.

Ibrahim, I.K., Handoo, Z.A. 2007. A survey of cyst nematodes (Heterodera spp.) in Northern Egypt. Pakistan Journal of Nematology. 25:335-337.

Last Modified: 4/17/2014
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