First report of the Soybean Cyst Nematode, Heterodera glycines, in New York

Authors: Wang, Xiaohong; BERGSTROM, GARY - Cornell University; CHEN, SHIYAN - Cornell University; THURSTON, DAVID - Cornell University; CUMMINGS, JAIME - Cornell University; Handoo, Zafar; Hult, Maria; Skantar, Andrea

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2017
Publication Date: 6/30/2017
Citation: Wang, X., Bergstrom, G., Chen, S., Thurston, D., Cummings, J., Handoo, Z.A., Hult, M.N., Skantar, A.M. 2017. First report of the Soybean Cyst Nematode, Heterodera glycines, in New York. Plant Disease. https://doi.org/10.1094/PDIS-06-17-0803-PDN.
DOI: https://doi.org/10.1094/PDIS-06-17-0803-PDN

Interpretive Summary: The soybean cyst nematode (SCN; Heterodera glycines) is the most damaging pathogen of soybean causing more than $1 billion in yield losses annually in the United States. Prior to 2016, SCN was detected in all major soybean-producing states in the U.S. except West Virginia and New York. Soybean shows great economic promise in NY and its acreage in the region has been expanding rapidly. Assessment of soybean diseases including SCN has been conducted since 2013 in NY and a recent soil sample from a soybean field in Cayuga County was found to contain nematode cysts, which were further confirmed as the soybean cyst nematode by morphological and molecular analyses. This is the first detection of SCN in New York and studies are urgently needed for effective management of this destructive soybean pest in New York fields.

Technical Abstract: The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is the most damaging pathogen of soybean (Glycine max (L.) Merr.), causing more than $1 billion in yield losses annually in the United States (Koenning and Wrather 2010). The SCN distribution map updated in 2014 showed that SCN were detected in all major soybean-producing states in the U.S. except West Virginia and New York (Tylka and Marett 2014). Soybean shows great economic promise in NY and its acreage in the region has been expanding rapidly. In coordination with a statewide soybean disease survey, soil samples have been collected from seventeen counties throughout NY since 2013 to search for the presence of SCN. A post-harvest soil sample collected in the fall of 2016 from a soybean field in Cayuga County, NY was processed using the sugar centrifugal-flotation method and a few brown and lemon-shaped cysts, similar to SCN, were isolated. The lemon-shaped cysts were light to dark brown and had a zigzag pattern and ambifenestrate vulval cone. Morphometrics of cysts (n = 5) included body length (L) including neck (520 to 866 µm, mean = 696.0 µm); body width (W) (320 to 495 µm, 399.8 µm); L/W (1.4 to 2.1, 1.7 µm); neck length (60 to 100 µm, 74.0 µm) and width (45 to 55 µm, 50.0 µm); fenestra length (52 to 65 µm, 58.4 µm) and width (32 to 40 µm, 37.4 µm); well-developed underbridge (70 to 110 µm, 80.0 µm); vulval slit (42 to 52 µm, 48.2 µm); and many bullae varying from round to finger-like. Second-stage juveniles (J2s) were vermiform. Lateral field with four incisures equally spaced. Stylet robust with anteriorly protruding knobs. Tail tapering uniformly to a finely rounded terminus. The key morphometrics of J2s (n = 15) included length of body (range = 381 to 510 µm, mean = 438.5 µm); stylet (22.5 to 25.0 µm, 23.8 µm); tail (42 to 50 µm, 47.3 µm), and hyaline tail terminus (22.5 to 27.5 µm, 25. 1 µm). Morphology of the cysts and J2s was in agreement with those of Heterodera glycines (Ichinohe 1952; Subbotin et al. 2010). Genomic DNA was extracted from manually hatched juveniles (n = 3) and ribosomal DNA of the ITS and 28S regions were PCR amplified using primers TW81 and AB28, and D2A and D3B (Skantar et al. 2012), respectively. PCR products were cleaned with the Monarch DNA Gel Extraction Kit (NEB, Ipswitch, MA) and cloned into vector pSC-A-amp/kan using the StrataClone PCR Cloning Kit (Agilent, Santa Clara, CA). Plasmid DNA was prepared with the Monarch Plasmid Miniprep Kit (NEB) and sequenced by Macrogen, Inc. All nucleotide sequences (KY795943-KY795945; KY794755-KY794765) were submitted to GenBank. A BLASTN search was performed to verify the identity of the sequences. The three 28S sequences were identical to one another and 100% identical to those of H. glycines from China (GU595446) and 99% identical to several other accessions. The ITS sequences varied at between 2-6 bp; the consensus sequence from all clones matched a Chinese population sequence (HM560783) at 99% identity. BLASTN of individual ITS sequences matched several other H. glycines sequences in GenBank at 99% identity. These morphological and molecular analyses confirmed the identity of the nematode species as Heterodera glycines. To our knowledge, this is the first report of SCN in New York. The HG type of the SCN population needs to be determined in order to deploy appropriate resistant cultivars for managing SCN in the infested field.