Multigene phylogeny of root-knot nematodes and molecular characterization of Meloidogyne nataliei Golden, Rose & Bird, 1981 (Nematoda: Tylenchida)

Sergio Álvarez-Ortega,Janete A. Brito,Sergei. A. Subbotin

doi:10.1038/s41598-019-48195-0

Abstract

The root-knot nematodes of the genus Meloidogyne are highly adapted, obligate plant parasites, consisting of nearly one hundred valid species, and are considered the most economically important group of plant-parasitic nematodes. Six Meloidogyne species: M. arenaria, M. hapla, M. incognita, M. microtyla, M. naasi and M. nataliei were previously reported in Michigan, USA. For this study, Meloidogyne nataliei was isolated from the grapevine Vitis labrusca from the type locality in Michigan, USA, and was characterized using isozyme analysis and ribosomal and mitochondrial gene sequences. No malate dehydrogenase activity was detected using macerate of one, five, six, seven or ten females of M. nataliei per well. However, one strong band (EST = S1; Rm: 27.4) of esterase activity was detected when using homogenates of ten egg-laying females per well. Phylogenetic analyses of sequences of the partial 18S ribosomal RNA, D2-D3 of 28S rRNA, internal transcribed spacer of rRNA, mitochondrial cytochrome oxidase subunit I genes and the cytochrome oxidase subunit II-16S rRNA intergeneric fragment from fifty-five valid Meloidogyne species and M. nataliei were conducted using Bayesian inference and maximum likelihood methods. From these results, we infer 11 distinct clades among studied species, with M. nataliei and M. indica composing a basal lineage. Seventy five percent of these species belong to seven clades within the Meloidogyne superclade. Characterization of these clades is provided and evolutionary trends within the root-knot nematodes are discussed.

Highlights

The root-knot nematodes (RKNs) of the genus Meloidogyne are highly adapted obligate plant parasites
During a nematology survey conducted at multiple sites in Southwest Michigan in 2017, several grape root and soil samples were collected from the type locality of M. nataliei
The females of M. nataliei protrude from the root surface and they are usually cover by a massive eggs mass (Fig. 1)

Summary

Introduction

The root-knot nematodes (RKNs) of the genus Meloidogyne are highly adapted obligate plant parasites. Their worldwide distribution and broad host range (parasitizing nearly every species of higher plant) contribute to their status as the most economically important group of plant-parasitic nematodes[1]. Meloidogyne nataliei is characterized by its unique morphology, cytogenetics and biology It was detected in 1977 from root samples of grape During 1983–1984 an attempt to eradicate this nematode species in the type locality was made[6], but it was rediscovered on the original farm in 2012 and 20174 While this species is morphologically and cytologically well characterized, no molecular and isozyme data are available for M. nataliei. We leverage these collected specimens to i) perform molecular and isozyme analysis of M. nataliei; ii) elucidate evolutionary relationships of M. nataliei with its congeners while iii) gaining insight on the phylogeny of the root-knot nematodes using a multigene dataset containing species reference sequences of partial 18S rRNA, the D2-D3 of 28S rRNA, ITS1 rRNA partial COI mtDNA gene and the COII-16S rRNA intergeneric fragment

Methods

Results

Conclusion