First Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in Ohio

Abstract

HomePlant DiseaseVol. 101, No. 7First Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in Ohio PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in OhioK. E. Ankrom, H. Lopez-Nicora, T. L. Niblack, and L. E. LindseyK. E. AnkromSearch for more papers by this author, H. Lopez-NicoraSearch for more papers by this author, T. L. NiblackSearch for more papers by this author, and L. E. LindseySearch for more papers by this authorAffiliationsAuthors and Affiliations K. E. Ankrom , Department of Horticulture and Crop Science, Ohio State University, Columbus 43210 H. Lopez-Nicora T. L. Niblack , Department of Plant Pathology, Ohio State University, Columbus 43210 L. E. Lindsey , Department of Horticulture and Crop Science, Ohio State University, Columbus 43210. Published Online:5 May 2017https://doi.org/10.1094/PDIS-12-16-1728-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In a statewide soybean survey in June of 2013, 2014, and 2015, 588 soil samples were collected from fields planted to soybean (Glycine max) in 36 counties representing the soybean production area of Ohio. The soil had variable amounts of sand, silt, and clay, and the fields were planted to corn (Zea mays) or soybean during the previous year. Nematodes were extracted from 100 cm3 soil from each sample by decanting and sieving followed by sucrose centrifugal flotation. Phytoparasitic nematodes were identified and counted based on morphological traits to genus at 40× to 100× magnification. Pin nematodes (Paratylenchus spp., family Tylenchulidae) were detected in 69, 52, and 36% of fields sampled in 2013, 2014, and 2015, respectively. Paratylenchus species can cause substantial crop loss (Braun and Lownsbery 1975; Wang et al. 2016). Females accounted for a large percentage (>50%) of the Paratylenchus populations in some soybean samples, which suggested that they were actively reproducing on soybean. The maximum number of Paratylenchus observed in a single sample was 3,346/100 cm3 soil; the nematode was initially identified as P. projectus, which reduced soybean yield at lower population densities (Niblack 1992). Individuals from one sample were hand-picked and identified to species under a compound light microscope as P. neoamblycephalus Geraert (Ghaderi et al. 2014). The females (n = 20) had conical truncate heads, strong spears (s = 29.3 to 33.9 μm, mean = 31.4 μm), and rounded basal knobs. The cuticles were distinctly annulated, with lateral fields containing 4 incisures. Present were single, outstretched ovaries as well as posteriorly located vulvae (mean v = 83.2). Spermathecae were present without sperm and no males were observed. The anus was often obscure, with tail conical and tapering in shape. Body length ranged from 349.6 to 435.0 μm (mean = 397.0 μm). These morphological traits were consistent with Paratylenchus observed from all the Ohio fields. DNA was extracted from five adult females (n = 5) and the 18S rRNA region was amplified with the 5′-3′sequence of the 18s primer pair, forward: CGAATRGCTATTACAACAGC (23 bases); and the reverse: GCGGTATCTGATCGCC (18 bases). PCR products were purified, sequenced, and deposited in GenBank (GenBank accession no. KY584087). The sequence was compared with previously deposited sequences by means of a BLASTN search, which resulted in a 97% identity match with P. neoamblycephalus (AY284634.1). No previously deposited sequence for the D2/D3 molecular marker for the 28S rRNA region existed for P. neoamblycephalus; ours is the first deposited for this marker region (KY584086). One soil sample with 150 P. neoamblycephalus/100 cm3 soil was used to infest soybean cultivar Lee 74. After 12 weeks in a greenhouse maintained at 27°C, the P. neoamblycephalus population increased to more than 1,000/100 cm3 soil (reproduction factor [RF] 6.7). This increase was split into three pots (∼300 P. neoamblycephalus/pot) of Lee 74, and after 10 weeks at 27°C each pot had RF >1 (1.3 to 6.9). The molecular and morphological observations confirmed the presence of P. neoamblycephalus in the sample, and the greenhouse tests confirmed soybean as a host. The nematode has been reported from commercial vegetables in Tennessee (Bernard 1980), but not from soybean. Management recommendations for soybean will depend on its distribution and pathogenicity. To our knowledge, this is the first report of P. neoamblycephalus in Ohio and as a parasite of soybean.