Morphological and molecular characterization of Pratylenchus dakotiensis n. sp.(Nematoda: Pratylenchidae), a new root-lesion nematode species on soybean in North Dakota, USA

Authors: Handoo, Zafar; YAN, GUIPING - North Dakota State University; KANTOR, MIHAIL - Orise Fellow; HUANG, DANQIONG - North Dakota State University; CHOWDHURY, INTIAZ - North Dakota State University; PLAISANCE, ADDISON - North Dakota State University; Bauchan, Gary; Mowery, Joseph

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2021
Publication Date: 1/17/2021
Citation: Handoo, Z.A., Yan, G., Kantor, M., Huang, D., Chowdhury, I.A., Plaisance, A., Bauchan, G.R., Mowery, J.D. 2021. Morphological and molecular characterization of Pratylenchus dakotiensis n. sp. (Nematoda: Pratylenchidae), a new root-lesion nematode species on soybean in North Dakota, USA. Plants. 10(168):1-13. https://doi:10.3390/plants10010168.
DOI: https://doi.org/10.3390/plants10010168

Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plant roots and cause an estimated ten billion dollars of crop loss each year in the United States and 100 billion dollars globally. Lesion nematodes are the most economically important groups of plant-parasitic nematodes that damage the roots of many kinds of plants worldwide. One problem with determining the extent of damage to crop plants is that the nematodes present in many areas are not known, such as in North Dakota. In this study a team of ARS scientists and colleagues from North Dakota State University identified from a soybean field in Richland County, ND, a new species of lesion nematode by both morphological and molecular means. They also discovered how to distinguish the new species from closely related species with molecular and anatomical features. This discovery is significant because new molecular and morphological information obtained for this new species will facilitate future identifications of this lesion nematode. Therefore, this research will be used by scientists, diagnosticians, growers, action agencies, and extension agencies involved in nematode research and control.

Technical Abstract: Root-lesion nematodes (Pratylenchus spp.) of the genus Pratylenchus Filipjev, 1936 are among the most important nematode pests on soybean (Glycine max (L.) Merr.) along with soybean cyst and root-knot nematodes. In May 2015 and 2016 a total of six soil samples were collected from a soybean field in Walcott, Richland County, ND and submitted to the Mycology and Nematology Genetic Diversity and Biology Laboratory (MNGDBL), USDA, ARS, MD. Later, in 2019, additional nematodes recovered from a greenhouse culture on soybean originally from the same field were submitted for further analysis. Males, females and juveniles of Pratylenchus sp. were recovered from the soil samples using the sugar centrifugal flotation method and were examined morphologically and molecularly. DNA from single nematode was extracted and three regions were characterized by sequencing 28S D2-D3, ITS rDNA, and cytochrome oxidase subunit I (COI) gene. Phylogeny trees were constructed to ascertain the relationships with other Pratylenchus spp., and PCR-RFLP was performed to compare the banding patterns. Molecular analysis indicated that it is a new, unnamed Pratylenchus sp. that is different from three morphologically closely related Pratylenchus spp., including P. convellariae, P. pratensis, and P. fallax. Morphologically, another closely related specie is P. flakkensis. However, they differ in several characters such as having high head with 3 annules, slightly longer stylet in females, higher vulva % and longer spicule in males. In conclusion, both morphological and molecular observations with known and above mentioned closely related species indicate that the North Dakota isolate on soybean represents a new root-lesion nematode species which is named and described herein as Pratylenchus dakotiensis n. sp.