Rotylenchulus Reniformis Research Articles

Nematicide influence on cotton yield and plant-parasitic nematodes in conventional and sod-based crop rotation.

Plant-parasitic nematodes (Rotylenchulus reniformis (reniform, RN), Helicotylenchus dihystera (spiral), and Mesocriconema ornatum (ring)) and yield were investigated in cotton phases of conventional (peanut–cotton–cotton) and sod-based (bahiagrass–bahiagrass–peanut–cotton) rotations with or without irrigation and fluopyram nematicide at a long-term research site, established in 2000, in Quincy, Florida, USA. Objectives were to determine impacts of nematicide application on cotton yield and evaluate effects of nematicide on plant-parasitic nematodes in these rotations in 2017 and 2018. Reniform nematode population densities were greater in conventional cotton than sod-based cotton. Ring and spiral nematode population densities were greater in sod-based cotton than conventional cotton. Plots receiving nematicide had increased RN population densities in preplant 2018 soil samples and spiral nematode population densities in preplant 2017, harvest 2017, preplant 2018, and harvest 2018 soil samples compared to untreated plots. Cotton seed yield in conventional rotation was increased by 18% following nematicide application in 2017 but decreased by 10% in sod-based rotation in 2018, relative to the untreated control. Sod-based rotation had greater cotton yield than conventional rotation in 2017 and 2018. Nematicide application did not improve cotton yield in sod-based rotation and was inconsistent in conventional rotation.

Determining the Profitability of Reniform Nematode Control Practices in the Mississippi Cotton Production System

The reniform nematode, Rotylenchulus reniformis, can be damaging in silt loam soils that have predominantly supported cotton (Gossypium hirsutum L.) production in the Mid-Southern United States. The objective of this research was to determine the profitability of integrated nematode management options in Mississippi cotton production in soils naturally infested with the reniform nematode. Experiments were conducted near Hamilton, MS, in 2016 and Oswego and Tchula, MS, in 2017. Commercially available seed treatments included a base seed treatment of azoxystrobin + fludioxonil + mefenoxam and seed-applied nematicides including thiodicarb + imidacloprid and fluopyram. In-furrow nematicides included aldicarb and fluopyram + imidacloprid. Lastly, 1,3-dichloropropene was applied preplant to soil followed by cotton seed with and without treatment. Cotton yield was 40 kg/ha greater when 1,3-dichloropropene was applied, and a base fungicide seed treatment was utilized compared with the base seed treatment alone. Cotton yield was at least 73 kg/ha greater when the base seed treatment was followed by aldicarb or fluopyram + imidacloprid in-furrow compared with seed treatments alone. Economic analyses suggested that seed treatment and in-furrow nematicides without 1,3-dichloropropene provided the greatest return on investment.

Susceptibility of four passion fruit species to the reniform nematode

Abstract Reniform nematode (Rotylenchulus reniformis) is a major pest of sour-passion fruit (Passiflora edulis) in Brazil, and few management methods are currently available, mainly due to the lack of host-plant resistance. Other species of passion fruit species are also commercially available in Brazil, which could be a source of resistance. Cultivars of three species (P. setacea ‘BRS-Pérola-do-Cerrado’, P. cincinnata ‘BRS-Sertão-Forte’, and P. alata ‘BRS-Mel-do-Cerrado’), and one susceptible cultivar (P. edulis BRS-Gigante-Amarelo) were evaluated for reniform nematode susceptibility in two greenhouse trials. Results showed that the cultivars were susceptible. Therefore, reniform nematode management in passion fruit must be rely on a combination of nematode-free seedlings and nematode-free fields.

Yield Loss of Cotton Cultivars Due to Rotylenchulus reniformis and the Added Benefit of a Nematicide

The objective was to determine cotton yield loss due to Rotylenchulus reniformis and document any yield benefit from the addition of a nematicide. Field trials were established in two adjacent fields: one infested with R. reniformis and one where R. reniformis was not detected. In both fields, seven cotton cultivars were planted with and without Velum Total (1.02 liters/ha). In 2017, R. reniformis reduced cultivar yields by an average of 59% between the noninfested and the R. reniformis-infested field. The nematicide application increased seed cotton yields in the R. reniformis field by 55%, and no yield increase was observed in the noninfested field. In 2018, R. reniformis reduced seed cotton yields by an average of 42% between the noninfested field and the R. reniformis-infested field. Across the cultivars, addition of the nematicide increased seed cotton yields by an average of 6% in the R. reniformis-infested field and an average of 8% in the noninfested field. The nematicide reduced R. reniformis eggs per gram of root by an average of 92% in 2017 and 78% in 2018 across all cotton cultivars. Overall, R. reniformis reduced seed cotton yields by 50%, which was equivalent to 2,225 kg/ha.

First report of Rotylenchulus reniformis infecting turmeric in Vietnam and consequent damage.

Turmeric (Curcuma longa L.) is one of the common medicinal crops of high economical value in Vietnam. A survey in the Central Highlands of Vietnam revealed a turmeric growing area showing serious disease symptoms, including stunting of the plant, yellowing or darkening of the leaf margins and tips, and underdeveloped dry and rotten rhizomes. An inspection for plant pathogens in soil samples from this area revealed a high density and frequency of Rotylenchus reniformis, with a significant relationship between the density of R. reniformis, rhizome weight, and level of plant damage. This study provides the first report of R. reniformis found in parasitic association with turmeric in Vietnam with the support of molecular data and examines its resulting damage.

Evaluation of Seed Treatment, Herbicide, and Nematicide on Tobacco Thrips (Thysanoptera: Thripdae) and Reniform Nematode (Tylenchida: Hoplolaimidae) Control

Numerous pests infest cotton early in the season. Some economically important are Palmer amaranth, Amaranthus palmeri (S. Wats); tobacco thrips, Frankliniella fusca (Hinds); and reniform nematode, Rotylenchulus reniformis (Linford and Oliveira). Thrips and weed management are essential to prevent delayed maturity and reduced crop yield. A field study was conducted during 2015 and 2016 to evaluate the influence of insecticide seed treatment, herbicide, and nematicide on tobacco thrips and reniform nematode control, as well as the impact on cotton growth, development, and yield. Treatments consisted of insecticide seed treatment (insecticide seed treatment and fungicide only), herbicide application (S-metolachlor, glufosinate, S-metolachlor plus glufosinate, and no herbicide), and nematicide application (1, 3-dichloropropene and no nematicide). There were no significant interactions between insecticide seed treatment, herbicide, and nematicide for any parameter. Nor were there any interactions in respect to nematode densities, thrips densities, thrips injury, herbicide injury, or plant biomass. Nematode densities were reduced with the use of 1,3-dichloropropene when sampled at first square and post-harvest. Thrips densities and injury were reduced at the 1- to 2-leaf stage sample timing with an insecticide seed treatment, but not at the 3- to 4-leaf stage sample timing. Herbicide injury was the greatest following S-metolachlor plus glufosinate applications (< 12%). A significant interaction between nematicide and insecticide seed treatment was observed for cotton yield, where the use of 1,3-dichloropropene and the insecticide seed treatment resulted in greater yields than all other treatments.

Registration of four upland cotton germplasm lines with elevated levels of seed oil oleic acid

AbstractFour upland cotton (Gossypium hirsutum L.) germplasm lines, HOa1 (Reg. no. GP‐1072, PI 691652), HOa2 (Reg. no. GP‐1073, PI 691653), HOa3 (Reg. no. GP‐1074, PI 691654), and HOa4 (Reg. no. GP‐1075, PI 691655), with elevated levels of seed oil oleic acid were developed and released by the USDA‐ARS. High seed oil levels of oleic acid have been reported for a small number of G. barbadense L. accessions. Included among these accessions is GB713, which is also known as a source of reniform nematode (Rotylenchulus reniformis Linford and Oliveira) resistance and has been used to breed this trait into an upland cotton background. Root‐knot nematode resistance was bred into the GB713‐based reniform‐resistant lines to yield germplasm with resistance to both nematodes. Testing the nematode‐resistant lines for seed oil fatty acid composition revealed elevated levels of oleic acid in some seeds. Selection and propagation of individual plants with the highest oleate levels indicated that the trait was stable for three successive generations with approximately double the level of oleic acid found in normal cottonseed oil. Oils with high levels of oleic acid are considered to be healthier and have improved oxidative stability at elevated temperature, making them preferred for some cooking and frying applications.

Efficacy of soaking cotton seeds within salicylic acid and potassium silicate on reducing reniform nematode infection

ABSTARCTThe efficiency of soaking cotton cv. Giza 45 seeds in five concentrations of salicylic acid and potassium silicate (5, 10, 15, 20 and 25 mg L−1 against Rotylenchulus reniformis infection showed a significant (P < 0.05) improvement in the tested plant parameters that was distinct in soaked seeds in salicylic acid for 24 hours compared with potassium silicate in greenhouse (28 ± 5 °C). The application of concentration (20 mg L−1) stated the highest values of improvement of plant criteria, while high concentration (25 mg L−1) revealed the maximum reduction rates in the total nematode population for both potassium silicate and salicylic acid. Moreover, seed soaking in salicylic acid and potassium silicate achieved a considerable increment in nitrogen, phosphorus, potassium, phenol and chlorophyll contents in cotton leaves with changeable values.

Population survey of phytonematodes in soybean crop in the Middle Plateau region in Rio Grande do Sul

The objective of this study was to determine and quantify the main phytonematodes found in soybean crops in the state of Rio Grande do Sul and to estimate the population level where they are found. Therefore, samples of soil and soybean roots were received from 154 municipalities of the Middle Plateau region of Rio Grande do Sul, from 2014 to 2016. After receiving and registering the samples, nematodes were extracted, identified and quantified in each sample. Through these data, it was determined the absolute frequency (AF), relative frequency (RF), absolute density (AD) and relative density (DR) of each nematode genus as well as their average population level in the municipalities. The main genera found in the study were Meloidogyne (found in 7.5% of the samples), Pratylenchus (6.2%), Heterodera (4.3%), Rotylenchulus (1.6%) and Helicotylenchus (22.9%). The species Meloidogyne species was not identified, but for Pratylenchus two species were identified, P. brachyurus and P. zeae. Besides these two genera, others were found, among them Heterodera glycines, Rotylenchulus reniformis and Helicotylenchus dihystera. The most frequently found nematode was H. dihystera, and in relation to population level, Meloidogyne spp. stands out for showing the highest levels in the municipalities in the three years of evaluation.

Single Nucleotide Polymorphism Analysis Using KASP Assay Reveals Genetic Variability in Rotylenchulus reniformis.

This study employed single nucleotide polymorphisms (SNPs) to determine the genetic variability present in 26 isolates of Rotylenchulus reniformis from Louisiana, Mississippi, Arkansas, South Carolina, Georgia, Hawaii, and Alabama. Genomic DNA from reniform nematode was extracted and increased quantitatively using the process of whole genome amplification. More than 162 putative SNPs were identified, 31 of which were tested using a KASP kompetitive allele-specific PCR genotyping assay. Of the SNPs tested, 13, 17, and 19 SNPs revealed genetic variability within reniform nematode isolates from Louisiana, Mississippi, and Arkansas, respectively. Seven SNPs elucidated genetic differences among isolates of reniform nematode from Louisiana, Mississippi, and Arkansas. Eight SNPs determined genetic variability among individual isolates from South Carolina, Georgia, Hawaii, and Alabama. This study is the first to report genetic variability in geographic isolates of reniform nematode employing a SNP assay. This study also demonstrated that SNP markers can be used to evaluate isolates of R. reniformis and could be useful to assess their genetic diversity, origin, and distribution. Such information would be extremely useful in resistance breeding programs.

Genetic characterization of Gossypium arboreum accession PI 529740 for reniform nematode resistance

AbstractBreeding for reniform nematode (Rotylenchulus reniformis) resistance is hindered by the lack of resistance in upland cotton (Gossypium hirsutum) cultivars. Resistance has been frequently identified in accessions from the Gossypium arboreum germplasm collection with accession PI 529740 rated as highly resistant. Accession PI 529740 was crossed with the susceptible G. arboreum accession PI 529729 to develop an F2 population for genetic characterization. The population showed quantitative variation suggesting multiple genes conferred the resistant phenotype. Thirteen of the 216 F2 plants showed resistance similar to the resistant parent and these data supported a two recessive gene model. Sixty plants were classified as resistant or moderately resistant, indicating a single recessive gene conferred the moderately resistant phenotype. The classification of 24 F2:3 families for nematode resistance generally supported the classification of the corresponding F2 plants; however, most families were highly variable for infection with no families rated as resistant. This information will aid in the introgression of resistance into upland cotton as larger populations will be required to successfully recover resistance conferred by multiple recessive genes.

Screening Cotton Genotypes for Reniform Nematode Resistance.

A rapid non-destructive reniform nematode (Rotylenchulus reniformis) screening protocol is needed for the development of resistant cotton (Gossypium hirsutum) varieties to improve nematode management. Most protocols involve extracting vermiform nematodes or eggs from the cotton root system or potting soil to determine population density or reproduction rate. These approaches are generally time-consuming with a small number of genotypes evaluated. An alternative approach is described here in which the root system is visually examined for nematode infection. The protocol involves inoculating cotton seedling 7 days after planting with vermiform nematodes and determining the number of females attached to the root system 28 days after inoculation. Data are expressed as the number of females per gram of fresh root weight to adjust for variation in root growth. The protocol provides an excellent method for evaluating host-plant resistance associated with the ability of the nematode to establish an infection site; however, resistance that hinders nematode reproduction is not assessed. As with other screening protocols, variation is commonly observed in nematode infection among individual genotypes within and between experiments. Data are presented to illustrate the range of variation observed using the protocol. To adjust for this variation, control genotypes are included in experiments. Nonetheless, the protocol provides a simple and rapid method to evaluate host-plant resistance. The protocol has been successfully used to identify resistant accessions from the G. arboreum germplasm collection and evaluate segregating populations of more than 300 individuals to determine the genetics of resistance. A vegetative propagation method for recovering plants for resistance breeding was also developed. After removal of the root system for nematode evaluation, the vegetative shoot is replanted to allow the development of a new root system. More than 95% of the shoots typically develop a new root system with plants reaching maturity.

Effects of cover crops on Rotylenchulus reniformis and Hanseniella sp. populations

Until the last decade, pest management in a pineapple crop was efficiently done using pesticides. However, most of the pesticides are now banned for use in European overseas territories. An alternative is to establish a rotation, or rotations, between pineapple and plants that limit the development of these parasites. We tested 32 plants (mainly Fabaceae and Poaceae) for their potential to decrease the soil inoculum of the nematode Rotylenchulus reniformis and of the symphylid Hanseniella sp., the two main parasites affecting the growth and the production of pineapple crops in Martinique. Several field, greenhouse and climatic chamber experiments showed that among the cover plants tested Crotalaria juncea and C. spectabilis showed a strong suppressiveness for both parasites.

Convergent evolution of saccate body shapes in nematodes through distinct developmental mechanisms

BackgroundThe vast majority of nematode species have vermiform (worm-shaped) body plans throughout post-embryonic development. However, atypical body shapes have evolved multiple times. The plant-parasitic Tylenchomorpha nematode Heterodera glycines hatches as a vermiform infective juvenile. Following infection and the establishment of a feeding site, H. glycines grows disproportionately greater in width than length, developing into a saccate adult. Body size in Caenorhabditis elegans was previously shown to correlate with post-embryonic divisions of laterally positioned stem cell-like ‘seam’ cells and endoreduplication of seam cell epidermal daughters. To test if a similar mechanism produces the unusual body shape of saccate parasitic nematodes, we compared seam cell development and epidermal ploidy levels of H. glycines to C. elegans. To study the evolution of body shape development, we examined seam cell development of four additional Tylenchomorpha species with vermiform or saccate body shapes.ResultsWe confirmed the presence of seam cell homologs and their proliferation in H. glycines. This results in the adult female epidermis having approximately 1800 nuclei compared with the 139 nuclei in the primary epidermal syncytium of C. elegans. Similar to C. elegans, we found a significant correlation between H. glycines body volume and the number and ploidy level of epidermal nuclei. While we found that the seam cells also proliferate in the independently evolved saccate nematode Meloidogyne incognita following infection, the division pattern differed substantially from that seen in H. glycines. Interestingly, the close relative of H. glycines, Rotylenchulus reniformis does not undergo extensive seam cell proliferation during its development into a saccate form.ConclusionsOur data reveal that seam cell proliferation and epidermal nuclear ploidy correlate with growth in H. glycines. Our finding of distinct seam cell division patterns in the independently evolved saccate species M. incognita and H. glycines is suggestive of parallel evolution of saccate forms. The lack of seam cell proliferation in R. reniformis demonstrates that seam cell proliferation and endoreduplication are not strictly required for increased body volume and atypical body shape. We speculate that R. reniformis may serve as an extant transitional model for the evolution of saccate body shape.

Survey of nematodes associated with Flowering plants in Khordha district, Odisha

A survey was carried out to study the association of nematodes with ornamental flowering plants in 105 locations of Khordha district, Odisha during November 2014 to May 2015 by collecting soil samples from rhizosphere of 34 ornamental flowering plants (OFP). Estimation of mean nematode population/200 cc soil samples revealed the presence of eight plant parasitic nematodes and three groups of free living nematodes. Among eight plant parasitic nematodes, Hoplolaimus indicus was associated with highest number of OFP (24) followed by Rotylenchulus reniformis (22), Helicotylenchus dihystera (16), Xiphinema insigne (20), Meloidogyne incognita (8) Criconemella ornata (4), Caloosia exilis (2) and Tylenchorhynchus mashhoodi (1). In context to free living nematodes, Dorylaimids were associated with highest number of OFP (31) followed by Rhabditids (27) and Mononchids (12). Community analysis of nematodes species associated with 34 OFP indicated that the highest prominent value was recorded in R. reniformis (179.4) followed by M. incognita (36.4), H. indicus (26.1), H. dihystera (24.3), X. insigne (17.2), T. mashhoodi (5.5), C. ornate (3.7) and C. exilis (0.3) in descending order. Rotylenchulus reniformis occurred in high densities, which was 233.5 nematodes/200 cc soil followed by followed by M. incognita (83.5), T. mashhoodi (58.0), H. dihystera (36.2), H. indicus (30.5), C. ornata (15.3). As regards to free living nematodes, Dorylaimids were having highest frequency (93.3%), mean density (39.3) and prominence value (38.0) followed by Rhabditids and Mononchids.

Validation of the Chemotaxis of Plant Parasitic Nematodes Toward Host Root Exudates

Plant parasitic nematodes (PPN) are microscopic soil herbivores that cause damage to many economic crops. For the last century, it has been proposed that chemotaxis is the primary means by which PPN locate host plant roots. The identities and modes of action of chemoattractants that deliver host-specific messages to PPN, however, are still elusive. In this study, a unique multidimensional agar-based motility assay was developed to assess the impacts of root exudates on the short-range motility and orientation of PPN. Three PPN (Rotylenchulus reniformis, Meloidogyne incognita and Heterodera glycines) and root exudates from their respective host and non-host plants (cotton, soybean, and peanut) were used to validate the assay. As predicted, R. reniformis and M. incognita were attracted to root exudates of cotton and soybean (hosts), but not to the exudates of peanut (non-host). Likewise, H. glycines was attracted to soybean (host) root exudates. These results underpinned the intrinsic roles of root exudates in conveying the host specificity of PPN. In particular, PPN selectively identified and targeted to hydrophilic, but not hydrophobic, fractions of root exudates, indicating that groundwater should be an effective matrix for chemotaxis associated with PPN and their host plant interactions.

A genomic resource for the sedentary semi-endoparasitic reniform nematode, Rotylenchulus reniformis Linford & Oliveira.

The reniform nematode (Rotylenchulus reniformis) is a sedentary semi-endoparasitic species that is pathogenic on many row crops, fruits, and vegetables. Here, the authors present a draft genome assembly of R. reniformis using small- and large-insert libraries sequenced on the Illumina GAIIx and MiSeq platforms.

Plant Parasitic Nematodes Associated with Wheat in Northern and Middle Egypt

Distribution and identification of phytonematodes associated with wheat grown in twelve provinces of Northern and Middle Egypt were investigated during two growing seasons (2016-2017 and 2017-2018). A total of 929 soil and root samples were collected from 119 localities (villages/farms) belonging to 37 districts. Samples contained fourteen nematode genera and species viz., Aphelenchoides, Criconemella, Ditylenchus, Helicotylenchus, Heterodera, Hirschmanniella oryzae, Hoplolaimus, Longidorus,Meloidogyne, Pratylenchus, Rotylenchulus reniformis, Tylenchorhynchus, Ttylenchus and Xiphinema. The stunt nematodes (Tylenchorhynchus spp.), the root-lesion nematodes (Pratylenchus spp.), the spiral nematodes (Helicotylenchus spp.) and the cyst nematodes (Heterodera spp.) were the most frequent nematodes in all samples. The stunt nematodes had the highest occurrence with 47.4%, population density with 48.2 and prominence value with 33.2. The root-lesion nematodes ranked the second after Tylenchorhynchus spp., in terms of frequency of occurrence (13.77%), while the cyst nematodes had the second order after the stunt nematodes, in terms of population density (24.8) and prominence value (5.4). The spiral nematodes occupied the third rank, in terms of frequency of occurrence (5.5%), and the last rank in terms of both of population density and prominence value (9 and 2.1, respectively).

Screening Cucurbit Rootstocks for Resistance to Meloidogyne spp. and Rotylenchulus reniformis

Fusarium wilt [caused by the fungus Fusarium oxysporum f. sp. niveum (FON)] has been a consistent problem in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] production worldwide. One method for combatting this pathogen in the field is to graft a susceptible, high-yielding scion on to a fusarium wilt-resistant rootstock. A concerning issue with rootstocks resistant to fusarium wilt is that they have not been tested for their susceptibility to plant pathogenic nematodes—specifically, root-knot nematodes (RKNs; Meloidogyne spp.) and the reniform nematode (Rotylenchulus reniformis). Preliminary findings have demonstrated that many of these Fusarium-resistant rootstocks are highly susceptible to RKNs. Research was conducted during the Spring and Fall 2015 and 2016 to evaluate the resistance to RKN and reniform nematode in rootstocks with known resistance to fusarium wilt. Six rootstocks were evaluated over the course of four experiments. A nematode-susceptible interspecific hybrid [Cucurbita maxima (Duchesne) × C. moschata (Duchesne)] rootstock ‘Carnivor’ was included as a susceptible control in both years. Results demonstrated that several Citrullus lanatus var. citroides (L.H. Bailey) rootstocks (‘Carolina Strongback’, USVL246-FR2, USVL252-FR2, and USVL-360) and ‘SP-6’ (a commercially available pollinizer cultivar) exhibited resistance to plant parasitic nematodes when compared with the susceptible control. Partial resistance was observed in USVL-482351. When compared with the control, these rootstocks also had fewer Meloidogyne spp. and R. reniformis in root tissue. These findings indicate that rootstocks may be available to manage both fusarium wilt and RKN in grafted cucurbit production system.

Morpho-molecular characterization of Colombian and Brazilian populations of Rotylenchulus associated with Musa spp.

Three populations, two from Colombia and one from Brazil, of Rotylenchulus reniformis associated with banana and plantain, were characterized using morphological, morphometric, and molecular methods. Morphometric data from these populations were similar to type and reference populations of R. reniformis. Partial sequences of both D2-D3 rDNA and mitochondrial cytochrome oxidase subunit I (COI) regions had a strong affinity (99% similarity) to previously published sequences of R. reniformis. Phylogenetic analyses (maximum likelihood and Bayesian inference) suggested that the Colombian populations of R. reniformis corresponded to the previously described Type A of the species. This is the definitive first report in Colombia of R. reniformis associated with banana and plantain crops.