The population of
species group was detected from the soil surronding the roots of peach (
) during a survey of plant-parasitic nematodes in Gilgit-Baltistan, Pakistan. From the results of the ...morphological study, the species was identified as
. Morphometrics of
generally agree with those of the type species and the topotype specimens. Molecular analysis of 18S rDNA of
from Pakistan indicated two nucleotide differences and 99 % similarity with the Chinese (AM086669) and the Australian (AM086685) population of
. Phylogenetic analysis of 18S rDNA placed the Pakistanis population close to
from China and Australia. This species is reported for the first time from Pakistan
Three populations of Xiphinema primum n. sp. and two populations of X. pachtaicum were recovered from natural forests and cultural regions of northern Iran. Both species belong to the X. ...americanum-group and were characterized by their morphological, morphometric and molecular data. The new species, which was recovered in three locations, belongs to the X. brevicolle-complex and is characterized by 2124-2981 μm long females with a widely rounded lip region separated from the rest of the body by a depression, 103-125 μm long odontostyle, two equally developed genital branches with endosymbiont bacteria inside the ovary, which are visible under light microscope (LM), vulva located at 51.8-58.0%, the tail is 26-37 μm long with a bluntly rounded end and four juvenile developmental stages. It was morphologically compared with nine similar species viz. X. brevicolle, X. diffusum, X. incognitum, X. himalayense, X. luci, X. parabrevicolle, X. paramonovi, X. parataylori and X. taylori. The second species, X. pachtaicum, was recovered in two geographically distant points close to city of Amol. Molecular phylogenetic studies of the new species were performed using partial sequences of the D2-D3 expansion segments of the large subunit ribosomal RNA gene (LSU rDNA D2-D3), the internal-transcribed spacer rDNA (ITS = ITS1+5.8S+ITS2), and the mitochondrial cytochrome c oxidase I gene (COI mtDNA) regions. The Iranian population of X. pachtaicum was also phylogenetically studied based upon its LSU rDNA D2-D3 sequences. Both species were also inspected for their putative endosymbiont bacteria. Candidatus Xiphinematobacter sp. was detected from two examined populations of the new species, whereas the second endosymbiont bacterium, detected from three examined isolates of X. pachtaicum, was related to the plant and fungal endosymbionts of the family Burkholderiaceae. The phylogenetic analyses of the two endosymbiont bacteria were performed using partial sequences of 16S rDNA. In cophylogenetic analyses, significant levels of cophylogenetic signal were observed using both LSU rDNA D2-D3 and COI mtDNA markers of the host nematodes and 16S rDNA marker of the endosymbiont bacteria.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In 2018 to 2019, soil and root samples from some declining peach orchards were collected in Edgefield County, South Carolina, USA. Excavated roots of Guardian
peach (
) rootstock showed strong gall ...symptoms. Extracted root-knot nematodes (RKN) were identified by both morphological and molecular methods as
. This is the first detection of the peach RKN in South Carolina and the third state in the USA after Florida and California.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Xiphinema americanum
group has a cosmopolitan distribution, with several species having particular importance as virus-vectors of four economically important nepoviruses naturally occurring in the ...USA with IAI quarantine status for Europe. The morphological diagnosis of the species is problematic due to the limited diagnostic characters, overlapping morphometrics and incomplete taxonomic descriptions. An ongoing issue within the
X. americanum
group is the determination of species belonging to the
X. brevicolle
subgroup. By using a phylogenetic framework, molecular and morphometric data of the topotype population we demonstrate that certain of the published DNA sequences have been misidentified and belong to closely related species such as
X. taylori
,
X. diffusum
or unknown/unidentified species. Studying again the morphology and morphometrics of populations identified as
X. brevicolle
from the Czech Republic the identity, phylogenetic position and genetic variability of these populations have been clarified. These belong to a different species that is described herein as
X. parataylori
n. sp. Multi-gene phylogenies were reconstructed using nuclear ribosomal (18S rRNA gene, ITS1 and ITS2 regions, D2-D3 expansion segments of 28S rRNA gene) and mitochondrial DNA (partial
cox
1 and
nad
4) and the position of
X. brevicolle
(topotype population) to the most closely related species is shown. Morphology and species specific sequences were linked and the worldwide distribution discussed. The validity of
X. brevicolle
and the long-standing controversies about the taxonomic status of
X. diffusum
and
X. taylori
have been clarified.
Xiphinema taylori
and
X. diffusum
may represent complexes of cryptic species, however more comprehensive studies involving additional populations and materials from the type localities are needed to support this hypothesis.
One new and three known species of the genus
Xiphinema
from the rhizosphere of fruit trees and rose shrubs in East Azarbaijan province, Iran, are presented based on the morphological, morphometric ...and molecular characters. The new species is distinguished by its 2.0-2.1 mm long body, relatively flattened lip region with 8.7-10.0 µm width, set off from body contour by a deep constriction, odontostyle 82.5-88.0 µm long, V = 52-54, reproductive system didelphic-amphidelphic with symbiotic bacteria in the reflexed ovaries, tail conoid, dorsally convex with rounded to slightly subdigitate tip (42.0-43.5 µm long, c = 61-65, c′ = 1.6-1.8), and males unknown. The new species,
X. babaii
sp. n
., looks very close to
X. californicum
, and is regarded as its cryptic species, being separated from it using some morphological differences. Their separation was further corroborated using molecular data. Three known species belonging to the
Xiphinema americanum
group namely
X. primum
,
X. pachtaicum
and
X. simile
were also collected during present study, and new data were provided for them.
Xiphinema simile
is a new record for the Iran's nematode fauna. Molecular phylogenetic studies using partial sequences of 28S rRNA gene D2-D3 fragments were performed, and the phylogenetic relationships of the new species were discussed.
Dagger and needle nematodes included in the family Longidoridae (viz. Longidorus, Paralongidorus, and Xiphinema) are highly polyphagous plant-parasitic nematodes in wild and cultivated plants and ...some of them are plant-virus vectors (nepovirus). The mitochondrial (mt) genomes of the dagger and needle nematodes, Xiphinema rivesi, Xiphinema pachtaicum, Longidorus vineacola and Paralongidorus litoralis were sequenced in this study. The four circular mt genomes have an estimated size of 12.6, 12.5, 13.5 and 12.7 kb, respectively. Up to date, the mt genome of X. pachtaicum is the smallest genome found in Nematoda. The four mt genomes contain 12 protein-coding genes (viz. cox1-3, nad1-6, nad4L, atp6 and cob) and two ribosomal RNA genes (rrnL and rrnS), but the atp8 gene was not detected. These mt genomes showed a gene arrangement very different within the Longidoridae species sequenced, with the exception of very closely related species (X. americanum and X. rivesi). The sizes of non-coding regions in the Longidoridae nematodes were very small and were present in a few places in the mt genome. Phylogenetic analysis of all coding genes showed a closer relationship between Longidorus and Paralongidorus and different phylogenetic possibilities for the three Xiphinema species.
There is a significant knowledge gap with regard to non-filarial nematodes and their relationships, if any, with intracellular bacteria, with only sporadic reports in the literature. An intracellular ...bacteria Xiphinematobacter, belonging to subdivision 2 of the Verrucomicrobia, was previously reported in the ovaries of three species of the non-filarial Xiphinema americanum-group of nematodes. We explored the diversity of Xiphinematobacter in 22 populations of X. americanum sourced from six continents and conservatively have identified nine phylotypes, six of which have not previously been reported. A geographic basis to the phylotypes was noted with phylotypes A and B only found in Europe, whereas phylotypes F, G, H and I were mainly found in North America. Phylotypes C, D and E showed greater geographical variation. Sequences of Xiphinematobacter from this study help to inform the taxonomy of Verrucomicrobia such that the status and composition of Verrucomicrobia subdivision 2 potentially requires reflection.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The dagger nematodes of the longidorids can cause diseases of various agronomic and horticultural crops, and are consisted of more than 260 valid species. In a forest survey of ecotypes of longidorid ...nematodes, from the root zone soil of Brant’s oak, (
Lindl.) and hawthorn (
L.) trees, three species of
group namely
,
and
were collected and studied based on their morphological and morphometric characters.
is prevalent
species in Iran. In this paper additional data for
and
species are presented.
is a new record for nematode fauna of Iran.
The Xiphinema americanum-group is a large species complex containing more than 50 nematode species. They are economically important because they are vectors of nepoviruses. The species ...differentiation of X. americanum-group is problematic because the species share similar morphological characters. In the present study we collected nematode samples from different locations in the USA, Italy and Russia. Six valid species, X. americanum s. str., X. brevicolle, X. californicum, X. pachtaicum, X. rivesi and X. simile, and four unidentified putative Xiphinema species were characterised by morphology and sequencing of D2-D3 of 28S rRNA, ITS1 rRNA and mitochondrial COI genes. New nematode sequences generated totalled 147. Phylogenetic relationships of the X. americanum-group species reconstructed by Bayesian inference for D2-D3 of 28S rRNA gene sequences did not provide clear species delimitation of the samples studied, although the mtDNA presented interspecific variations useful for demarcation among species. Xiphinema americanum s. str., X. californicum, X. pachtaicum, X. rivesi, and two unidentified Xiphinema species were found in 72 soil samples from California. We also reconstructed the phylogenetic relationships using partial 16S rRNA gene sequences within endosymbiotic bacteria of the genus Candidatus Xiphinematobacter and provided solid evidence for distinguishing 17 species of this genus based on the analysis of new and previously published sequences. Fifty-five new bacterial sequences were obtained in the present study and comparison of the bacterial 16S rRNA and nematode COI phylogenies revealed a high level of co-speciation events between host and symbiont.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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