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Sergei A. Subbotin

Summary

Rapid diagnosis tools for detection of root-knot nematodes play an important role in the disease control and eradication programme. Recombinase polymerase amplification (RPA) assays were developed targeting the IGS rRNA gene of the pacara earpod tree root-knot nematode, Meloidogyne enterolobii. The RPA assays using TwistAmp® Basic and TwistAmp® exo kits allowed detection of M. enterolobii from gall tissues and crude nematode extracts of all stages of target species without a DNA extraction step. The results of real-time RPA assays using a real-time fluorescent detection of a series of crude nematode extracts showed reliable detection with sensitivity of 1/10 of a second-stage juvenile in a RPA reaction tube after 15-20 min. The RPA assay provides affordable, simple, fast and sensitive detection of M. enterolobii.

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Dieter Turhan and Sergei Subbotin

Abstract

Two species of cyst-forming nematodes belonging to the goettingiana group are described from woodland in Germany. Heterodera circeae sp. n., parasitising Circaea lutetiana (Onagraceae), most closely resembles H. carotae and H. cruciferae, from which it differs by larger cysts (430-720 μm) and longer fenestral length (27-54 μm) and rounded stylet knobs of the second-stage juveniles. Heterodera scutellariae sp. n., found on the labiate Scutellaria galericulata (Lamiaceae), is distinguished from the other species of this group by shorter body (358-437 μm) and tail (41-53 μm) of the second-stage juveniles. The ITS-rDNA sequences of the new species are very similar and differ from each other by only a few nucleotides. The phylogenetic position of the new species within the group is presented based on analyses of molecular data. A revised diagnosis of the goettingiana group is proposed. The species of the group have lemon-shaped, ambifenestrate and abullate (small bullae occasionally present) cysts with egg sac, long vulval slit (> 35 μm), thin vulval bridge, low semifenestrae (average fenestral length 30-45 μm), and weak underbridge. Second-stage juveniles are characterised by body length > 400 μm, tail length > 45 μ m, hyaline tail portion > 20 μm, stylet length > 20 μm, lateral field with four incisures and small phasmids. All known species of the goettingiana group exclusively parasitise dicotyledonous plants.

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Sergei E. Spiridonov and Sergei A. Subbotin

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David J. Hunt and Sergei A. Subbotin

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Sergei A. Subbotin, Mundo-Ocampo and J. Baldwin

Volume 8 in the series, appearing in two parts, A and B, deals with the systematics of cyst nematodes of the subfamily Heteroderinae. Cyst nematodes are important pathogens causing extensive damage and significant yield loss to many crops in both temperate and tropical regions. Part A presents summarised information on various aspects of morphology, biology, ecology, pathology, biogeography, control measures and diagnostics of these nematodes. Molecular diagnostic tables and comprehensive tabular and dichotomous keys for species identification, together with descriptions of protocols for extraction, light and electron microscopy studies, and molecular diagnostics are also included. The taxonomic section of part A provides diagnoses for six genera, viz., Globodera, Punctodera, Cactodera, Dolichodera, Betulodera and Paradolichodera, and includes descriptions and morphometrics of 30 valid species. The work is illustrated by 101 drawings and photos. The genus Heterodera is mainly covered in part B, complete descriptions and morphometrics of the 80 known valid species being provided and the species illustrated by 159 line drawings and photos. Identification of the species using morphological and molecular techniques is also covered. Each part includes an extensive bibliography.
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Sergei A. Subbotin, Mundo-Ocampo and J. Baldwin

Volume 8 in the series, appearing in two parts, A and B, deals with the systematics of cyst nematodes of the subfamily Heteroderinae. Cyst nematodes are important pathogens causing extensive damage and significant yield loss to many crops in both temperate and tropical regions. Part A presents summarised information on various aspects of morphology, biology, ecology, pathology, biogeography, control measures and diagnostics of these nematodes. Molecular diagnostic tables and comprehensive tabular and dichotomous keys for species identification, together with descriptions of protocols for extraction, light and electron microscopy studies, and molecular diagnostics are also included. The taxonomic section of part A provides diagnoses for six genera, viz., Globodera, Punctodera, Cactodera, Dolichodera, Betulodera and Paradolichodera, and includes descriptions and morphometrics of 30 valid species. The work is illustrated by 101 drawings and photos. The genus Heterodera is mainly covered in part B, complete descriptions and morphometrics of the 80 known valid species being provided and the species illustrated by 159 line drawings and photos. Identification of the species using morphological and molecular techniques is also covered. Each part includes an extensive bibliography.
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J.J. Chitambar and Sergei A. Subbotin

The sheath nematodes belonging to the superfamily Hemicycliophoroidea are unique amongst all plant parasitic nematodes known to man due to the presence of an extra cuticular covering or sheath over the inner cuticle and body of all juvenile and adult life stages. These plant-parasitic nematodes include species of agricultural and quarantine importance.
In Systematics of the Sheath Nematodes of the Superfamily Hemicycliophoroidea John Chitambar and Sergei Subbotin provide a detailed review of the taxonomy and diagnosis of the superfamily, its member genera and 153 related species based on their morphological and molecular analyses, as well as a further understanding of the relationships within the superfamily using molecular phylogenetics. In addition, Chitambar and Subbotin also give detailed information on the global distribution, biology, host-parasite relationships and ecology of sheath nematodes.
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Sergei Subbotin, Maurice Moens and Lieven Waeyenberge

Abstract

Amplified ITS region products of rDNA from 25 valid species and one unidentified species from the genus Heterodera and from Meloidodera alni were digested by 26 restriction enzymes. A combination of seven enzymes clearly separated the agriculturally most important species from each other and from their sibling species. Species specific digestion profiles of ITS regions and a table with approximate sizes of digested fragments for several identification enzymes are given. Heterogeneity of ITS regions was revealed for some cyst forming nematode species. Des fragments amplifiés de la région de l’ITS du rDNA de 25 espèces valides et d’une espèce non identifiée du genre Heterodera et de Meloidodera alni ont été soumis à une digestion par 26 enzymes de restriction. La combinaison de sept enzymes a permis une séparation nette des espèces les plus importantes en agriculture, tant les unes par rapport aux autres que par rapport aux espèces jumelles. Sont donnés les profils spécifiques de digestion des régions de l’ITS et un tableau regroupant les tailles approximatives des fragments digérés pour plusieurs enzymes d’identification. L’hétérogénéité des régions de l’ITS a été révélée chez quelques espèces de nématodes à kyste.

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Sergei Subbotin, Maurice Moens and Deliang Peng

Abstract

A method for rapid identification of juveniles and cysts of the soybean cyst nematode based on PCR with species specific primers is described. The PCR assay was tested on 53 populations originating from China, Russia, USA and Brazil. A single cyst or second stage juvenile of Heterodera glycines alone or in a mixture with other soil inhabiting nematodes was detectable.

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Sergei Subbotin, Zahra Tanha Maafi and Maurice Moens

Abstract

RFLP and sequences of ITS-rDNA of 45 populations of cyst-forming nematodes collected from different parts of Iran were analysed and identified as representatives of 21 species. Eight enzymes generated RFLP for all studied populations. Comparison of RFLP profiles and sequences of the ITS regions with published data confirmed the presence of Heterodera avenae, H. filipjevi, H. glycines, H. hordecalis, H. latipons, H. schachtii and H. trifolii in Iran. RFLP patterns and ITS sequences for H. elachista, H. turcomanica, H. mothi and C. cacti were obtained for the first time in this study. Heterodera humuli, H. goettingiana, H. fici, H. elachista, H. turcomanica and Cactodera cacti are recorded for the first time in Iran. These results correspond with morphological and morphometric identification of the populations. Several populations were not identified at the species level and are attributed to Heterodera sp.; some of these may correspond to new species. Twenty-one new sequences from Iranian cyst-forming nematodes and 36 known sequences were used for the phylogenetic analyses. The cyst-forming nematodes formed several clades corresponding to their morphological features. Heterodera mothi and H. elachista clustered with high support with other Cyperi group species and H. turcomanica formed a moderately to highly supported clade with the Humuli group.