First Report of Cyst Nematode (Heterodera iri) in Ohio

Abstract

HomePlant DiseaseVol. 102, No. 5First Report of Cyst Nematode (Heterodera iri) in Ohio PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Cyst Nematode (Heterodera iri) in OhioS. Joseph, F. Akyazi, A. Habtewld, T. Mekete, T. Creswell, G. E. Ruhl, and J. FaghihiS. JosephSearch for more papers by this author, F. AkyaziSearch for more papers by this author, A. HabtewldSearch for more papers by this author, T. MeketeSearch for more papers by this author, T. Creswell†Corresponding author: T. Creswell; E-mail: E-mail Address: creswell@purdue.eduSearch for more papers by this author, G. E. RuhlSearch for more papers by this author, and J. FaghihiSearch for more papers by this authorAffiliationsAuthors and Affiliations S. Joseph F. Akyazi A. Habtewld T. Mekete , Entomology and Nematology Department, University of Florida, Gainesville, 32611 T. Creswell † G. E. Ruhl , Plant and Pest Diagnostic Laboratory, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907 J. Faghihi , Department of Entomology, Purdue University, West Lafayette, IN 47907. Published Online:23 Mar 2018https://doi.org/10.1094/PDIS-11-17-1846-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat The cyst nematodes (Heterodera spp.) are a major group of plant-parasitic nematodes and of great economic importance in many countries throughout the world, causing considerable yield losses to many important crops (Jones et al. 2013). The cereal cyst nematodes (CCNs) are a widespread and important group of cyst nematodes that restrict production of cereal crops throughout the world (Rivoal and Cook 1993). The CCNs that belong to the Heterodera avenae complex infect roots of cereals and grasses (Handoo 2002). Four species from this group have been reported in the United States, including H. avenae, H. filipjevi, H. mani, and H. ustinovi (syn. H. iri). H. iri has previously been reported only in New York, Michigan, Connecticut, Massachusetts, and Rhode Island (LaMondia and Wick 1992). Cyst nematodes were identified from an Ohio bentgrass golf course sample submitted to the Purdue Plant and Pest Diagnostic Lab and the Purdue Nematology Lab for diagnosis in 2016. The affected turf had irregular patches of thinning, translucent leaves, and reduced root systems. Cysts were collected from the infested soil by the modified Jenkins sugar flotation method (Jenkins 1964) and identified by morphological and molecular study. Morphometrics (mean ± SD) of second-stage juveniles (n = 12): body length = 661.7 ± 23.8 µm; a = 29.6 ± 1.3 µm; c = 7.3 ± 0.3 µm; c′ = 5.2 ± 0.5 µm; stylet length = 27.3 ± 0.5 µm; maximum body width = 22.4 ± 0.4 µm; body width at anus = 17.5 ± 2.1 µm; tail length = 90.9 ± 5.1 µm; hyaline tail length = 55.4 ± 4.8 µm; and hyaline tail /stylet length = 2.1 ± 0.2 µm. Morphometrics of cysts (n = 10): length (without neck) = 654.4 ± 82.9 µm; width = 461.8 ± 84.2 µm; neck length = 127.4 ± 20.8 µm; length/width = 1.4 ± 0.2. The vulval cone was bifenestrate with a strong vulval bridge and conspicuous bullae. Morphometrics of vulval cone (n = 7): fenestral length = 42.4 ± 4.1 µm; fenestral width = 24.4 ± 2.1 µm; vulval slit = 12.9 ± 1.4 µm; and vulval bridge = 3.1 ± 0.5 µm. Eggs (n = 10) measured length = 136.5 ± 8.9 µm; width = 43.7 ± 2.8 µm; and length/width = 3.1 ± 0.3. These morphological measurements were highly similar with those for H. iri as described by Mathews (1971). Genomic DNA was extracted from five nematodes. The ribosomal region spanning the internal transcribed spacer (ITS) 1, 5.8S gene, and ITS2 was amplified with forward primers AB28F (5′-GTTTCCGTAGGTGAACCTGC-3′) and reverse primer TW81R (5′-ATATGCTTAAGTTCAGCGGGT-3′). A 973-bp fragment was amplified, and the polymerase chain reaction product was purified and sequenced. The sequence was deposited in GenBank (accession no. KX611142). BLAST search results revealed a sequence similarity of 99% with H. iri (e.g., GenBank accession nos. AY148407.1 and AF274400.1) over 100% query cover. Morphological and molecular identification demonstrated that the population of cyst nematodes from Ohio was H. iri. Reproduction on bentgrass was demonstrated by inoculating 1,000 viable eggs onto 5-week-old bentgrass seedlings grown in 4-in. pots (n = 2) of sterilized sand at 23°C. A pot of noninoculated seedlings served as a control. Sixty days after inoculation, cysts were harvested from the plants, and extraction produced approximately 2,000 eggs, demonstrating multiplication on this host. No cysts were found on the control plants. To our knowledge, this detection represents a new record of H. iri in Ohio.