Molecular characterization of root-knot nematodes (Meloidogyne spp.) from Arkansas, USA

Abstract

Root-knot nematodes (Meloidogyne spp.) are the most common major pathogens of many crops throughout the world, impacting both the quantity and quality of marketable yields. In this study, a total of 244 root-knot nematode populations from various hosts from 39 counties in Arkansas were tested to determine the species diversity. Molecular characterization was performed on these populations by DNA sequencing of the ribosomal DNA 18S-ITS-5.8S, 28S D2/D3 and a mitochondrial DNA fragment flanking cytochrome oxidase gene subunit II - the intergenic spacer. Five species were identified, including M. incognita (Kofoid & White, 1919) Chitwood, 1949 from soybean, cotton, corn and various vegetables (232 samples); M. hapla Chitwood, 1949 from rose (1 sample); M. haplanaria Eisenback, Bernard, Starr, Lee & Tomaszewski, 2003 from okra, tomato, peanut, Indian hawthorn, ash, willow and elm trees (7 samples); M. marylandi Jepson & Golden in Jepson, 1987 from grasses (3 samples); and M. partityla Kleynhans, 1986 from pecan (1 sample) through a combined analysis of DNA sequencing and PCR by species-specific primers. Meloidogyne incognita is the most abundant species that was identified in 95% samples and was the only species in field crops including soybean and cotton, except for one population of M. haplanaria from soybean in Logan County (TK201). Species-specific primers were used to verify M. incognita through PCR by species-specific primers. Unlike historical data, M. arenaria, M. javanica and M. graminis were not detected from any of the samples collected during this study. This result is essential for effective and sustainable management strategies against root-knot nematodes in Arkansas.

Nematode Identification Techniques and Recent Advances

“…With the discovery of new species, however, perineal patterns became inadequate because perineal patterns (and other morphometric characters; [ 11 ]) overlapped between species [ 12 , 13 ]. Currently, RKN species are identified using a combination of morphological and molecular characteristics (e.g., [ 14 , 15 ]).…”

Biology, Taxonomy, and Management of the Root-Knot Nematode (Meloidogyne incognita) in Sweet Potato

“…e M. incognita is the most abundant species identified when compared with other studied species (95%) by this method [54]. A multiplex assay can also be used to identify tropical species of M. incognita, M. javanica, and M. arenaria [56].…”

“…is method was applied by sequencing the deoxyribonucleic acid (DNA) of ribosomal (18S-ITS-5.8S, 28S D2/D3) and mitochondrial fragment flanking cytochrome oxidase genes. It requires the combined analysis of DNA sequencing and polymerase chain reaction (PCR) for the species-specific primers to verify M. incognita [54]. M. incognita, M. enterolobii, and M. javanica could be identified by using three pairs of specific primers.…”

“…Resistance varieties of soybean against the elucidated M. incognita have a maximum amount of phenol, salicylic acid, chlorogenic acid, and ascorbic acid as compared to susceptible plants [54,132]. But the case of resistance in sweet potato plants is not yet described.…”

Effect of seed-applied fluopyram on Meloidogyne incognita infection and maturity in cotton and soybean

“…in the southern USA (Thomas and Kirkpatrick, 2001;Koenning, 2015). Furthermore, it is the most prevalent species of root-knot nematode in Arkansas (Ye et al, 2019). Seed cotton losses in 2018 were estimated at 2.4% (966,600 bales) across the US Cotton Belt (Lawrence et al, 2019).…”