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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Mycology and Nematology Genetic Diversity and Biology Laboratory » Research » Publications at this Location » Publication #323837
Title: First report of the stubby root nematode Paratrichodorus allius on potato in North Dakota

Author
item YAN, GUIPING - North Dakota State University
item PLAISANCE, ADDISON - North Dakota State University
item HUANG, DANQIONG - North Dakota State University
item UPADHAYA, ARJUN - North Dakota State University
item GUDMESTAD, NEIL - North Dakota State University
item Handoo, Zafar

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2016
Publication Date: 5/6/2016
Citation: Yan, G.P., Plaisance, A., Huang, D., Upadhaya, A., Gudmestad, N.C., Handoo, Z.A. 2016. First report of the stubby root nematode Paratrichodorus allius on potato in North Dakota. Plant Disease. 100(6):1247.

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. Stubby root nematodes are an important problem damaging the roots of many kinds of plants worldwide. One problem with determining the extent of damage to crop plants is that the nematodes present in many areas are not known, such as in North Dakota. This brief report describes how a team of North Dakota State University and ARS scientists identified from a potato field in Sargent County, ND, a species of stubby root nematode called Paratrichodorus allius by both morphological and molecular means. This discovery is significant because it is the first report of this nematode in North Dakota and the molecular information obtained will allow this nematode to be more easily distinguished from closely related species. Therefore, this research will be used by scientists, growers, action agencies, and extension agencies involved in nematode research and control.

Technical Abstract: Stubby root nematodes (Paratrichodorus and Trichodorus) are migratory ectoparasites that feed on roots and vector tobraviruses. These nematodes are important to the potato industry as they transmit Tobacco rattle virus (TRV) causing corky ringspot (CRS) disease that has a direct economic impact on growers due to abandon or rejection of crops for processing industry or fresh sale market. In October 2014, three soil samples were collected from a potato field in Sargent County, North Dakota to determine the occurrence of stubby root nematodes. Most of the field was harvested but a portion of the field was abandoned due to 80 to 90% of the tubers (cv. Milva) exhibiting brown necrotic rings, arcs and spots, typical symptoms of CRS. Diseased tubers from this field were tested and found to be infected with TRV. Nematodes were extracted and one of the samples was found to contain stubby root nematodes (44 per kg of soil) along with several other nematodes. In April 2015, forty-nine soil samples were collected from the same field and seven of the samples had stubby root nematodes ranging from 135 to 300 (mean = 175) per kg of soil. Nematodes were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 550.0 to 690.0 µm, mean = 606.8 µm), onchiostyle (40.0 to 47.5, 43.9), body width (35.0 to 58.0, 42.3), anterior end to basal bulb (90.0 to 150.0, 114.7), a (10.3 to 18.6, 14.7), b (4.0 to 6.7, 5.3), and V (50.0 to 60.0%, 53.8%). The anus and caudal pores are subterminal. The nematode species was identified as Paratrichodorus allius (Jensen, 1963) Siddiqi, 1974 according to morphological and morphometric characteristics (Decraemer, 1980). DNA was extracted from single nematodes (n = 7) isolated from three soil samples in 20 'l of extraction buffer (1×PCR buffer, 60 µg/ml Proteinase K). D2/D3 region of 28S rRNA, partial 18S rRNA, and ITS1 rDNA were amplified with primer pairs D2A/D3B, SSUF07/SSUR26 and BL18/5818, respectively. PCR products were cloned using pGEM-T easy vector and sequenced. Since sequences from all samples for each genomic region were identical, only one of the sequences from that region was submitted to GenBank and thus represents a consensus sequence. The 18S rRNA sequence (GenBank Accession No. KU094058, 919 bp) was 100% identical to one population of P. allius (AJ439572) from Washington, and was 99% identical to P. teres, a closely related species of P. allius, and less than 99% identical to other Paratrichodorus spp. The ITS1 rDNA sequence (KU094059, 832 bp) was 99% homologous with two populations of P. allius from North Carolina (KJ934124) and Washington (AM087124), but had no significant similarity with P. teres and other Paratrichodorus spp. The 28S D2/D3 sequence (KU094057, 799 bp) was 91% or less homologous with P. teres and other Paratrichodorus spp., but no P. allius sequence was available, indicating our P. allius population lacks similarity to P. teres and other species. The combination of the molecular tests confirmed the identity as P. allius. P. allius is known to be the most prevalent vector of TRV in Washington and Oregon. To our knowledge, this is the first report of P. allius in North Dakota.