Molecular and morphological characterization of Tylenchus zeae n. sp. (Nematoda: Tylenchida) from Corn (Zea mays) in South Carolina

Abstract

Specimens of a tylenchid nematode were recovered in 2019 from soil samples collected from a corn field, located in Pickens County, South Carolina, USA. A moderate number of Tylenchus sp. adults (females and males) were recovered. Extracted nematodes were examined morphologically and molecularly for species identification, which indicated that the specimens of the tylenchid adults were a new species, described herein as Tylenchus zeae n. sp. Morphological examination and the morphometric details of the specimens were very close to the original descriptions of Tylenchus sherianus and T. rex. However, females of the new species can be differentiated from these species by body shape and length, shape of excretory duct, distance between anterior end and esophageal intestinal valve, and a few other characteristics given in the diagnosis. Males of the new species can be differentiated from the two closely related species by tail, spicules, and gubernaculum length. Cryo-scanning electron microscopy confirmed head bearing five or six annules; four to six cephalic sensilla represented by small pits at the rounded corners of the labial plate; a small, round oral plate; and a large, pit-like amphidial opening confined to the labial plate and extending three to four annules beyond it. Phylogenetic analysis of 18S rRNA gene sequences placed Tylenchus zeae n. sp. in a clade with Tylenchus arcuatus and several Filenchus spp., and the mitochondrial cytochrome oxidase c subunit 1 (COI) gene region separated the new species from T. arcuatus and other tylenchid species. In the 28S tree, T. zeae n. sp. showed a high level of sequence divergence and was positioned outside of the main Tylenchus-Filenchus clade.

EXISTENCE, MOLECULAR IDENTIFICATION AND GENETIC VARIATION OF NEW ISOLATES OF SEED GALL NEMATODE Anguina tritici PARASITIZING ON WHEAT AND BARLEY IN IRAQ

“…Two universal primers were used for amplification of the internal transcribed spacer (ITS rDNA) region, which contains ITS1, 5.8S rRNA coding sequence, and ITS2 (Skantar et al,2012) included:10 Picomoles (pmol) of forward primer-TW81( 5'GTTTCCGTAGGTGAAC CTGC-3') and 10 pmol reverse primer-AB28 (5'ATATGCTTAAGTTCAGCGGGT-3') provided by Germany company (Jena Bioscience) for the five nematode isolates.The amplification was done as described by Michel and Sikora (2005).The amplified products and a phiX174 DNA / HaeIII marker were separated on 1.5 % agarose gel stained with Gel Red in 1 × TAE,where they were examined under UV light by UV Trans Illumination.…”