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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 #418019
Research Project: Plant-associated Nematode Management and Systematics and USDA Nematode Collection Curation

Location: Mycology and Nematology Genetic Diversity and Biology Laboratory

Title: Morphological and molecular characters of two Helicotylenchus species from South Africa and relationship of selected soil parameters with H. pseudorobustus

Author
item SHOKOOHI, EBRAHIM - University Of Limpopo
item RENSBURG, CANDICE - University Of The Free State
item Handoo, Zafar
item MASOKO, PETER - University Of Limpopo

Submitted to: Biologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2024
Publication Date: 9/7/2024
Citation: Shokoohi, E., Rensburg, C.V., Handoo, Z.A., Masoko, P. 2024. Morphological and molecular characters of two Helicotylenchus species from South Africa and relationship of selected soil parameters with H. pseudorobustus. Biologia. 79:3349-3359. https://doi.org/10.1007/s11756-024-01785-4.
DOI: https://doi.org/10.1007/s11756-024-01785-4

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that feed on plants and cause an estimated ten billion dollars of crop losses each year in the United States and 100 billion dollars globally. Spiral nematodes are one of the economically important groups of plant parasitic nematodes worldwide. In this study, two spiral nematode species were found in South Africa. Morphological and molecular characteristics were used to identify and distinguish the species. Scanning electron microscopy (SEM) of the species revealed that there were noticeable dissimilarities between the two species as did DNA. This study demonstrates SEM and DNA can be considered highly effective tools to accurately distinguish between the two species. Results are significant because the new molecular and morphological information obtained will facilitate future identifications of spiral nematodes and will be used by scientists, diagnosticians, growers, action agencies, and extension agencies involved in nematode research and control.

Technical Abstract: During a survey of plant-parasitic nematodes in South Africa's Limpopo Province, two species of Helicotylenchus were identified, namely H. dihystera and H. pseudorobustus. The morphological and molecular characteristics of these species were found to be consistent with those of the known species. A phylogenetic analysis of Helicotylenchus populations based on 28S rDNA was conducted, and it was found that the H. dihystera identified in this study belonged to the same group as other H. dihystera specimens with a 1.00 posterior probability support. Moreover, phylogenetic analysis of H. pseudorobustus based on 18S rDNA placed the test population close to other H. pseudorobustus specimens with 0.96 posterior probability. Scanning electron microscopy (SEM) for Helicotylenchus species also revealed noticeable dissimilarities in the labial disc and lateral field of the tail region between the two species from the present study, including H. pseudorobustus, and H. dihystera. The redundancy analysis (RDA) showed that H. pseudodrobustus had a correlation with pH and clay of the soil. In conclusion, despite the challenges associated with identifying Helicotylenchus species, SEM and rDNA markers can be considered as highly effective tools to distinguish the species correctly and accurately.