Root-lesion Nematode Research Articles

Population Development of the Root-Lesion Nematode Pratylenchus dakotaensis on Soybean Cultivars.

Two greenhouse experiments were conducted with the new species of root-lesion nematode, Pratylenchus dakotaensis, discovered in North Dakota, USA in 2017 and named in 2021. Experiment 1 was conducted to ascertain resistance levels of soybean (Glycine max [L.] Merr.) cultivars to the new species P. dakotaensis and Experiment 2 was conducted to evaluate the population levels of P. dakotaensis in roots versus soil. A total of 20 soybean cultivars, and the positive control, cultivar Barnes, accompanying a nonplanted control, were evaluated in both experiments; they each had five replicates and the experiments were repeated. Among the 20 soybean cultivars evaluated, a cultivar with the ID# 13 consistently produced the greatest population densities of P. dakotaensis across all the experiments and therefore it was selected as the susceptible check. The ratio of the final nematode population density of a test cultivar relative to the final population density of the susceptible check was used to scale resistance rating. Combined results of all the trials indicated that seven of the cultivars were moderately resistant, nine of the cultivars plus 'Barnes' were moderately susceptible, and four of the cultivars were susceptible. However, none of the cultivars tested were classified as resistant. Analysis of P. dakotaensis population levels revealed that ≥50% of the population resided in the root habitat and the remaining nematodes were recovered from soil at 9 weeks after planting for a majority of the cultivars tested. These results provide an insight into the virulence of P. dakotaensis on commercial soybean cultivars.

Interaction of root-lesion nematode (Pratylenchus thornei) and crown rot fungus (Fusarium culmorum) associated with spring wheat resistance under simulated field conditions

Interaction of root-lesion nematode (Pratylenchus thornei) and crown rot fungus (Fusarium culmorum) associated with spring wheat resistance under simulated field conditions

Early Detection and Temporal Dynamics of Pratylenchus scribneri Infection in Potato Roots Determined Using Quantitative PCR and Root Staining.

The root-lesion nematode, Pratylenchus scribneri, is a migratory endo-parasitic nematode that impacts potato production on a large scale. Effective management of this nematode requires an understanding of its population dynamics alongside early detection. Typically, the nematode population estimates are made from infested soil; however, considering the endo-migratory lifestyle of this nematode, it also is crucial to determine the nematode population residing inside the host roots. In this study, a SYBR green-based quantitative real-time PCR (qPCR) assay was developed for detection and quantification of P. scribneri in potato roots. The assay used a previously reported primer pair (ITS-2F/ITS-2R), and it proved to be specific and sensitive, detecting as low as 1/128th equivalents of a P. scribneri individual per 0.2 g of potato roots. The robustness of the assay was reflected in high correlation observed between the P. scribneri densities determined microscopically and the densities detected by qPCR in artificially inoculated (R2 = 0.93) and naturally infected (R2 = 0.73) root samples. A time-course experiment conducted in the greenhouse using qPCR detected P. scribneri in potato roots as early as 5 days after planting. The results correlated well with the microscopic observations (R2 = 0.80) and were complemented further with root staining. Additionally, three P. scribneri reproduction peaks were observed during one 3-month growth cycle of potato. Overall, the assay developed in this study is specific to P. scribneri in DNA extracts of root tissue and allows early detection and understandings of reproduction timings of this important nematode of potato.

Kök lezyon nematodlarının (Pratylenchus thornei) nohut bitkisinin rhizobium bakterileri üzerinde etkisi

Chickpea (Cicer arietinum) is one of the most significant legume crops and supply high-quality protein for human nutrition. legume crops such as chickpea are important agriculturally because of their symbiotic ability to nitrogen fixation with specific soil bacteria. Legumes like chickpea depend on nitrogen provided by the activity to grow, but these rhizobium bacteria are affected by plant-parasitic nematodes that cause less activity and decrease the number of nodules in the chickpea plant. The root-lesion nematodes (Pratylenchus thornei) are common and economically important pests described as one of the major limiting factors in agriculture and the growing chickpea field in the world. In this study, the effects of this nematode on the number of rhizobia (nodules) and rhizobium bacteria activity were assessed in both wild and domesticated accession of Cicer species under laboratory conditions. We inoculated all Cicer accession with the Mesorhizobium bacteria and with one species of the genus Pratylenchus (P. thornei). The result showed that P. thornei has a negative impact on the number of nodules and the activity of rhizobium bacteria. Nematode infection on chickpea caused decreased nodulation. Where, nematode infected plant formed 4-8 nodules/root and less nodule number than an uninfected plant.

Discovery of Root-Lesion Nematode (Pratylenchus scribneri) on Corn in Hainan Province of China.

Corn (Zea mays L.) is a very important cereal crop and serves as food, feed, and industrial material (Liu et al. 2016). The root-lesion nematode (RLN) is considered one of the most important plant-parasitic nematodes and can cause economic losses in agriculture worldwide (Jones et al. 2013). In January 2020, five samples were collected from a corn field in Lingshui Lizu Autonomous County, Hainan Province, China. The collected corn plants (cv. Denghai 685) were growing poorly and roots showed distinct lesions and rot. Corn fields with symptoms of stunted plants, and brown lesions on roots were widespread. This corn disease was severe in Lingshui Lizu Autonomous County. RLN were extracted from soil samples by the modified Baermann funnel (Hooper et al. 2005). All the samples contained RLN ranging from 9 to 82 (average 39) RLN per 100 cm3 of soil and 113 to 257 (average 194) RLN per 5 g roots. The extracted RLN were sterilized and cultured on carrot disks at 25°C for 90 days. Afterwards, seeds of corn (cv. Denghai 685) were sown in pots containing 1.8 liters of sterilized soil. Eight plants, one per pot, were infested with 1,000 RLN, eight pots of noninfested corn plants were used as controls, and plants were kept in a greenhouse at 25°C. At 75 days after inoculation, symptoms were like those initially observed in corn fields, whereas no symptoms were observed in the control plants. Nematodes in the soil and roots were extracted using the same method as previously described (Hooper et al. 2005). The average number of RLN per pot was approximately 4,250 in soil and 820 in roots, the reproduction factor (final number of nematodes/initial number of nematodes) was 5.07, no RLN were found in the control. The experiment was conducted twice. The morphological and molecular studies of RLN were examined to confirm species identification. The main morphological measurements of adult females (n = 15) included body length = 526.0 μm ± 17.1 (standard error) (range = 498.0 to 560.5 μm), stylet = 16.0 μm ± 0.3 (15.5 to 16.5 μm), tail length = 29.0 μm ± 1.5 (26.5 to 31.0 μm), a = 23.6 ± 0.6 (22.6 to 24.4), b = 5.6 ± 0.3 (5.2 to 6.0), c = 18.3 ± 0.9 (16.4 to 19.7), V = 78.2% ± 0.6 (77.4 to 79.2%), lip region with two annules. No males were found in the samples. This population was identified as Pratylenchus scribneri, based on the morphological characters (Castillo and Vovlas, 2007). DNA was isolated from individual nematodes followed by proteinase K-based lysis (Wang et al. 2011). The D2/D3 expansion region of the 28S rRNA gene, rDNA-internal transcribed spacer (ITS) region, and mitochondrial cytochrome oxidase I (mtDNA-COI) gene were amplified with primers D2A/-D3B (De Ley et al. 1999), TW81/ AB28 (Vovlas et al. 2011) and JB3/ JB5 (Liu et al. 2018), respectively. The PCR products were purified and ligated into pJET 1.2/blunt cloning vectors and transformed to Escherichia coli strain DH5α, and then sequenced. The obtained 28S rRNA gene D2/D3 region sequences (785bp), ITS sequences (886 bp) and mtDNA-COI (447bp) in this study were submitted to GenBank. The D2/D3 region of the 28S rRNA sequences of the RLN collected in Lingshui (GenBank accession no. MZ701843) showed 99.75% identity with P. scribneri sequences available in the GenBank (KX842628 and KX842625). The ITS sequences of the RLN collected in this study (MZ701842) showed the highest identity of 97.06% with P. scribneri sequences available in the GenBank (KX842626). The mtDNA-COI sequences of the RLN collected in this study (OK040228) showed 100% identity with P. scribneri (MN366409). Both morphological and molecular data confirmed the identity of P. scribneri. P. scribneri has been reported on corn in Inner Mongolia, Hebei, Shanxi, Shandong, Henan, Jiangsu, and Liaoning provinces of China (Li et al. 2019). As far as we know, this is the first report of P. scribneri on corn in Hainan Province, China. Since the RLN can cause considerable damage to corn, strategic measures should be taken to prevent the spread of P. scribneri to other regions in China.

Present status and future directions for management of root lesion nematode (Pratylenchus thornei) in chickpea

Chickpea is a popular legume crop in Asia and Africa's semi-arid regions. Crop production gains, on the other hand, have been modest, owing to biotic and abiotic stressors. Among the different biotic stresses, nematodes portray serious threat to chickpea production and colossal losses have been reported due to stress-free infection by other pathogens on infection with root lesion nematode (RLN). The worldwide distribution of two major species of RLN namely P. thornei and P. neglectus made them a focus research area especially on management aspect. In dryland farming areas of southeastern Australia, the P. thornei alone can cause yield losses of up to 40% in cereals and legumes. Despite the fact that chickpea breeders have been working persistently to generate superior chickpea varieties with increased resilience or tolerance to biotic and abiotic challenges, contemporary biotechnology technologies can help to speed up this process. To incorporate these tools and/or accelerate breeding programmes, identification of RLN resistant source with its genetic factor is first step in developing improved cultivars. However, study of resistance screening methods for chickpea against RLN is limited and standardization of different factors for development of a stable screening methodology distinguishing various levels of resistance is the need of the hour in RLN research.

Pratylenchus brachyurus Suppression by Organic Fertilizers and the Development of Soybean Plants

The root lesion nematode, Pratylenchus brachyurus (Godfrey) Filipjev & Schuurmans Stekhoven, has been caused significant losses in soybean crops in Brazil. The addition of organic fertilizers may suppress the population of these plant-parasitic nematodes. The aim of this work was to evaluate the action of cattle manure, cattle vermicompost, cattle compost, and slaughterhouse swine compost on the reduction of P. brachyurus population and the development in soybean plants (cv. NR 5909). The experiment was conducted for 90 days after P. brachyurus inoculation (DAI) in the pots, in greenhouse. At 90 DAI, shoots, roots and soil were collected from all experimental units to determine shoot dry matter, root fresh mass and nematodes quantification present in roots and soil. All the organic fertilizers promoted the increase of shoot dry matter and root fresh mass in relation to control, even under nematode infestation in soybean plants (cv. NR 5909). However, organic fertilizers did not promote a suppressive effect on P. brachyurus population in soybean plants.

Kök Lezyon Nematodlarının (Pratylenchus thornei (Sher et Allen) Pratylenchus neglectus (Rensch) Filipjev & Schuurmans Stekhoven (Tylenchida: Pratylenchidae) ve Soğan-sak Nematodu Ditylenchus dipsaci (Kühn, 1857) (Tyleneida) 'nın Nohut Yetiştirme Alanlarında Dikey Dağılımı

Investigation of the vertical distribution of three plant-parasitic nematodes was conducted in two southeastern (Şanlıurfa) and central Anatolia (Ankara) Turkey chickpea fields during 2015/2016 and 2016/2017 growing season. Twelve accessions of wild Cicer species representing three Cicer species (Cicer reticulatum L. and C. echinospermum L.) were used in the experiments for it. Soil samples were collected around the plant roots at a 10-20 cm and 20-30 cm depth by using an auger at each site. Maximum population densities of the root-lesion nematodes (Pratylenchus thornei (Sher et Allen) and (Pratylenchus neglectus (Rensch) Filipjev & Schuurmans) were observed at the depth of 20-30 cm, pod filling stage, and harvest time on most sampling. Also, the population density of root-lesion nematodes at the depths of 20-30 cm was observed as higher than Ditylenchus dipsaci (Kühn, 1857) (Tylenchida: Anguinidae) in the chickpea field. Population density of root-lesion nematodes was positively correlated with the contents of depth, site, time sampling, species chickpea, and there was determined significant difference between soil depth and population density of nematodes in both sites statistically.

Effect of Biofumigation on Population Densities of Pratylenchus spp. and Verticillium spp. and Potato Yield in Eastern Canada

Biofumigation has been proposed as an alternative to soil fumigation to manage soil-borne diseases including potato early dying disease complex (PED). This study examined the potential of using brown mustard (Mustard juncea) biofumigation to manage PED under rain-fed potato production in New Brunswick, Canada in two trials between 2017 and 2020 in comparison with chloropicrin fumigation and a conventional barley rotation. Biofumigation increased yield in one trial, but not in a second trial where the potato crop experienced severe drought, whereas chloropicrin fumigation increased yield in both trials. Biofumigation was effective in suppressing root-lesion nematode (RLN, Pratylenchus spp.) counts in both trials, but was ineffective in suppressing V. dahliae population density. Chloropicrin fumigation was effective in suppressing RLN counts and V. dahliae population density only in the hill where injected, but the effect was short-lived as the population density of V. dahliae in the hill increased to the level of the control in one potato growing season. Biofumigation may be an alternative to chloropicrin fumigation in managing PED, particularly in fields with high RLN population but relatively low Verticillium population density. However, neither biofumigation nor fumigation used alone may be sustainable in the short-term potato rotations commonly used in New Brunswick, and additional beneficial practices are required to sustain productivity in the long-term.

Interaction effect of Root Lesion Nematodes and Fusarium culmorum Sacc. on disease complex in some wheat cultivars

The study was conducted to assess a possible interaction between fungal pathogen of Fusarium culmorum Sacc. and Root lesion nematodes at sequentially and simultaneously inoculation. Fusarium culmorum spore suspension effect evaluated on plant disease severity and nematode density on moderate resistant wheat line to F. culmorum (2-49) and susceptible wheat variety (İkizce) under controlled condition. The disease severity was higher on İkizce cv. than 2-49. This indicates that there is a considerable important pathogen resistance. Simultaneous and sequential inoculation of Pratylenchus thornei and F. culmorum reduced the final nematode density and reproduction rate more than inoculation with only nematode on İkizce cv. The simultaneously P. penetrans and F.culmorum inoculation (N+F) affected the positively of final density on İkizce cv. The N+ F treatment affected the positively of P. neglectus density on İkizce cv., whereas negative effect was found in pre or post inoculation of F. culmorum treatments. No synergistic interactions were detected on 2-49 when plants were co-infected by the root lesion nematode and fungus. It was determined that P. thornei had a positive effect on disease severity when it entered the plant simultaneously and before the F. culmorum on İkizce cv.. The disease severity decreased in F. culmorum was applied four weeks after the P. neglectus treatment on 2-49 wheat line and İkizce cv. In the interaction with F. culmorum on İkizce cv., differences were determined between the species of root lesion nematodes.

Commercial Potato Cultivars Exhibit Distinct Susceptibility to the Root Lesion Nematode Pratylenchus penetrans

The root lesion nematode Pratylenchus penetrans is an important plant-parasitic nematode of potato. In this study, the susceptibility of commercial potato cultivars to P. penetrans was assessed. Nematode penetration was evaluated in cultivars Agria, Camel, Kennebec, Laura, Royata, and Stemster at 1, 3, 7, and 15 days after inoculation (DAI) with 750 nematodes/plant, and an egression assay at 3 DAI with 1000 nematodes/plant. Reproduction assays of cultivars Agata, Agria, Camel, Désirée, Dirosso, Kennebec, Laura, Picasso, Royata, and Stemster were performed in 2 L pots inoculated with four P. penetrans/g soil and quantified at 60 DAI. Tenue or moderate root cell browning to advanced necrotic areas were observed after nematode penetration, and the number of nematodes/g of root gradually increased with time of infection. A lower number of deposited eggs and nematodes were observed within the roots of cultivar Laura in all assays comparatively to other cultivars. The susceptibility index (SI) was significantly lower in cultivar Laura (0.4–0.6), followed by cultivars Camel and Picasso (0.8–0.9). All remaining cultivars showed SI values above 1. Although the potato susceptibility to the nematode varied among cultivars, no differences on the average number or weight of tubers produced by each plant of inoculated versus non-inoculated plants were detected. Our data reveals that these cultivars have a distinct ability to support the reproduction of P. penetrans.

Expanding the RNA virome of nematodes and other soil-inhabiting organisms.

In recent years, several newly discovered viruses infecting free-living nematodes, sedentary plant-parasitic nematodes, and migratory root lesion nematodes have been described. However, to the best of our knowledge, no comprehensive research focusing exclusively on metagenomic analysis of the soil nematode community virome has thus far been carried out. In this work, we have attempted to bridge this gap by investigating viral communities that are associated with soil-inhabiting organisms, particularly nematodes. This study demonstrates a remarkable diversity of RNA viruses in the natural soil environment. Over 150 viruses were identified in different soil-inhabiting hosts, of which more than 139 are potentially new virus species. Many of these viruses belong to the nematode virome, thereby enriching our understanding of the diversity and evolution of this complex part of the natural ecosystem.

Genome-Wide Association Study of Root-Lesion Nematodes Pratylenchus Species and Crown Rot Fusarium culmorum in Bread Wheat.

Triticum aestivum L., also known as common wheat, is affected by many biotic stresses. Root diseases are the most difficult to tackle due to the complexity of phenotypic evaluation and the lack of resistant sources compared to other biotic stress factors. Soil-borne pathogens such as the root-lesion nematodes caused by the Pratylenchus species and crown rot caused by various Fusarium species are major wheat root diseases, causing substantial yield losses globally. A set of 189 advanced spring bread wheat lines obtained from the International Maize and Wheat Improvement Center (CIMMYT) were genotyped with 4056 single nucleotide polymorphisms (SNP) markers and screened for root-lesion nematodes and crown rot resistance. Population structure revealed that the genotypes could be divided into five subpopulations. Genome-Wide Association Studies were carried out for both resistances to Pratylenchus and Fusarium species. Based on our results, 11 different SNPs on chromosomes 1A, 1B, 2A, 3A, 4A, 5B, and 5D were significantly associated with root-lesion nematode resistance. Seven markers demonstrated association with P. neglectus, while the remaining four were linked to P. thornei resistance. In the case of crown rot, eight different markers on chromosomes 1A, 2B, 3A, 4B, 5B, and 7D were associated with Fusarium crown rot resistance. Identification and screening of root diseases is a challenging task; therefore, the newly identified resistant sources/genotypes could be exploited by breeders to be incorporated in breeding programs. The use of the identified markers in marker-assisted selection could enhance the selection process and cultivar development with root-lesion nematode and crown rot resistance.

A Semi-supervised approach to cluster symptomatic and asymptomatic leaves in root lesion nematode infected walnut trees

• Pratylenchus vulnus infection in walnut detectable with hyperspectral data. • Agglomerative clustering with spectral angle mapper can isolate symptomatic leaves. • MDPA between control and infected histograms allows high-throughput phenotyping. • Rootstocks ranked least to most impacted by P. vulnus : VX211, MS1 122, MS1 127. Breeding strategies for many crops require quantitative evaluations of many genotypes from within as large of a diverse breeding pool as possible. In selecting pathogen tolerant genotypes, accurate and fast phenotyping to investigate genetic responses to pathogen infection and reproduction is crucial. Analyzing leaf tissues with spectral tools along with ground truth data offers potentially large gains in screening efficiency. However, ground truth labels per plant may not capture the effects of asymptomatic leaves and heterogeneous canopy responses to stress. We explored a semi-supervised clustering-based technique in which spectral patterns unique to and common among leaves from nematode infected plants are distinguished from patterns with no relationship to infection; we utilize these spectral patterns in ranking genotype tolerances to infection as a secondary objective. Proximal hyperspectral leaf scans (360 nm–1700 nm) of three walnut rootstock genotypes (MS1 122, VX211, MS1 127) were used in an agglomerative clustering procedure based on spectral angle mapper (SAM) distances to choose a spectral endmember representing the root lesion nematode, Pratylenchus vulnus , stress symptom on leaf per genotype. The histogram of SAM distances between control samples and the endmember was calculated. Next, the histogram of SAM distances between infected samples and the endmember was calculated. The shift between these histograms was then found using the minimum difference of pair assignments (MDPA) measure. The MDPA measures were 4.88, 3.14, and 5.48 for MS1 122, VX211, and MS1 127, respectively. This meant a genotype ranking in the order VX211, MS1 122 and, MS1 127 from the least affected by nematode infection to most impacted, which agreed with classification by nematological examinations of the plants. Clustering leaves based on their spectral response has the potential to overcome the limitation of heterogeneous canopy responses to stress in high-throughput phenotyping and other applications.

Population fluctuations and reaction of chickpea genotypes to root lesion nematodes (Pratylenchus thornei and P. neglectus) in Turkey

Population fluctuations and reaction of chickpea genotypes to root lesion nematodes (Pratylenchus thornei and P. neglectus) in Turkey

Biofertilizers in the control of Pratylenchus brachyurus in soybean crop

Nematodes are of great importance in soybean cultivation, especially the Pratylenchus brachyurus known as root lesion nematode. Its attack on plant roots causes less efficiency in the absorption of water and nutrients, in addition to damaging the plant's development. There is still no fully efficient method to control this phytopathogen, however, some products are available on the market, including biological control. Thus, the aim of this study was to evaluate commercial biological products in the efficiency of reducing the nematode population in soybean crop in Goiás, Brazil. The design was completely randomized in a 2x4 factorial scheme, the first factor being two soybean genotypes (Brasmax Bônus and Nidera NS 8383) and the second factor the treatments consisting of different dosages in an association of three commercial products: No-Estio®, Bio-fertility® and Radic®. The treatments used were: T1 control - without application of the products; T2 half the recommended dose; T3 the recommended dose and T4 a dose and a half that recommended by the manufacturer. Plant evaluation was carried out after 75 days of nematode inoculation. The results obtained showed that both cultivars hosted P. brachyurus, however, the treatments using the products had a lower population density of this nematode. It was concluded that the two soybean cultivars are hosts of Pratylenchus brachyurus. The agronomic character plant height was more affected when there was no application by the biological method. The association of No-Estio®, Bio-fertility® and Radic® products reduced the population density of nematodes in infected plants.

Identification and pathogenicity ofPratylenchus scribnerion tomato in Sichuan Province of People's Republic of China

AbstractRoot-lesion nematodes (Pratylenchusspp.) are a group of economically important pathogens that have caused serious economic losses in many crops. In 2019, root-lesion nematodes were recovered from tomato (Solanum lycopersicum) root samples collected from Sichuan Province, People's Republic of China (PRC). Extracted nematodes were disinfected, and one individual female was cultured on a carrot disc for propagation at 25 °C by parthenogenesis and designated the SC isolate. Afterwards, the isolate was identified on the basis of morphometric and molecular markers. Both morphometric characters and molecular analysis of the internal transcribed spacer region gene (ITS) of ribosomal DNA, the D2-D3 expansion region of the 28S rDNA gene and the mitochondrial cytochrome oxidase I (mtDNA-COI) gene revealed that the species of root-lesion nematode wasPratylenchus scribneri. The Bayesian tree inferred from the ITS rDNA, 28S rDNA and mtDNA-COI gene sequences also showed that this isolate formed a highly supported clade with otherP. scribneriisolates. The pathogenicity of the root-lesion nematode SC isolate on tomato was assessed, showing that tomato was a suitable host forP. scribneri. To the best of our knowledge, this is the first report ofP. scribnerion tomato in Sichuan Province, PRC. These are also the first molecular data obtained fromP. scribnerion tomato in the PRC, and the pathogenicity ofP. scribnerito tomato was studied for the first time. This study provides scientific data for the detection, identification and control of tomato root-lesion nematode disease.

Description of Rotylenchus zhongshanensis sp. nov. (Tylenchomorpha: Hoplolaimidae) and discovery of its endosymbiont Cardinium.

A new bisexual species of Rotylenchus is described and illustrated based on morphological, morphometric and molecular characterizations. Rotylenchus zhongshanensis sp. nov. is characterized by having a conoid lip region complying with the basic pattern for Hoplolaimidae, but with pharyngeal glands slightly overlapping intestine dorsally and cuticle thickened abnormally in female tail terminus. Females have robust stylet (30.1-33.8 μm). The pharyngeal gland has short dorsal (11.2-16.8 μm) overlap on the intestine. The vulva is located at 48.0-56.5% of body length, and phasmids are pore-like, 4-6 annuli posterior to the anus. For males, phasmids are pore-like, 11-17 annuli posterior to cloaca. The spicules are ventrally arcuate (21.0-28.5 μm) with gubernaculum in 5-8 μm length. The rRNA and mitochondrial COI genes were successfully sequenced from the assembled whole-genome sequences of the new species, and were used for reconstructing the phylogenetic relationships of the new species. A new strain of cyto-endosymbiont Cardinium was also discovered from the genome sequences of R. zhongshanensis sp. nov. The 16S rRNA phylogeny analyses revealed that this new bacterial strain is closed to that from cyst and root-lesion nematodes.

Phytonematodes as a limiting biotic factor of agricultural production in the world (review)

Purpose. To analyze domestic and foreign scientific literature on the species composition and harmfulness of the world's most dangerous parasitic species of phytonematodes in crops.
 Results. Today, according to the available literature, the most dangerous species of phytonematodes include: gall nematode (Meloidogyne spp.), cyst-forming nematode (Heterodera spp. and Globodera spp.), root lesion nematode (Pratylenchus spp.), banana drill nematode (Radoholus similis), stem nematode (Ditylenchus dipsaci), pine stem nematode (Bursaphelenchus xylophilus), reniform nematode (Rotylenchulus reniformis), xiphinema index (Xiphinema index), false head nematode (Nacobbus aberrans), and rice leaf nematode (Aphelenchoides besseyi).
 Conclusions. The results of research on the prevalence and harmfulness of parasitic nematode species in crops convince us of the need for a more detailed study of this group of microorganisms. Due to the rapid development of molecular genetic methods in the last decade, scientists have been able to expand and improve their knowledge of identifying species, races and pathotypes of phytonematodes, their biological and environmental characteristics, and most importantly, to discover and understand extremely complex mechanisms of parasite and host plants. Nematologists are confident that further research in these and other areas in the future will create a basis for developing a new strategy for long-term and environmentally safe control of these dangerous plant parasites.

Molecular and Morphological Characterization of The Root -lesion Nematode, Pratylenchus Neglectus, on Corn from Henan Province of China.

SummaryRoot-lesion nematodes, Pratylenchus spp., are economically important pathogens because of their detrimental and economic impact on a wide range of crops. In August 2018, two samples of both roots and rhizosphere soil were collected from a corn field in Liangyuanqu of Shangqiu city, Henan Province, China. Root-lesion nematodes were recovered from the roots and soil samples using the modified Baermann funnel extraction method. Both the morphological characters and molecular analysis of the internal transcribed spacer (ITS) and D2-D3 expansion region of 28S ribosomal RNA sequences confirmed that the root-lesion nematode population collected from corn in this study was P. neglectus. Phylogenetic analyses showed that this isolate formed a highly supported clade with other P. neglectus isolates. To the best of our knowledge, this is the first report of P. neglectus on corn in Henan Province of China. This study reports the first partial sequences of 28S D2-D3 region of P. neglectus on corn in China. Due to the great harmfulness of root-lesion nematodes to corn, care should be taken to prevent the spread of P. neglectus to other regions in China. At the same time, further study on the biological characteristics of P. neglectus is needed, which will be helpful to develop corresponding management and control strategies.