Integrated management of root-knot nematode (Meloidogyne incognita) for tomato production and productivity. Bayuh Belay1* ... important food and cash crop of the farmers and is ...... some part of the research budget without any reservation.
Full Text Available Introduction: Iran is among the world leading kiwifruit producers with 2.816 ha cultivated and 31.567 tones production. Plant parasitic nematodes cause damages to a variety of agricultural crops throughout the world. Interest in biological control of nematodes has increased because of the need for alternative methods to fumigant and non-fumigant nematicides and overall improvement of IPM programs. Bacterial species with nematicidal activity have also been used with some success for controlling root-knot diseases, including Streptomyces spp., Serratia spp., Bacillus spp. and Pseudomonas spp. The goal of the current study was to isolate, identify and investigate the potential of local Streptomyces bacteria for controlling and reducing root-knot nematode population in the north of Iran. Materials and Methods: In order to evaluate the effect of antagonistic bacteria on control of root-knot nematode of Kiwifruit, 100 isolates of bacteria were collected from Kiwifruit rhizosphere in the north of Iran and screened for pigmented microorganisms especially Streptomyces by applying standard serial dilution plate technique, using starch casein nitrate agar and glycerol asparagine agar. Morphological characterizations were achieved by the microscopic method. The microscopic characterization was done by cover slip culture method. The mycelium structure, color and arrangement of conidiospore and arthrospore on the mycelium were observed through the oil immersion (100X. The observed structure was compared with Bergey’s Manual of Determinative Bacteriology and the organism was identified. Various biochemical tests performed for the identification of the potent isolates are as follows: casein hydrolysis, starch hydrolysis, urea hydrolysis, esculin hydrolysis, acid production from sugar, NaCl resistance, temperature tolerance. Soil samples (100g were collected, and then processed for nematode egg and larvae extraction Hussey method. The suspension was pipetted
Full Text Available The root-knot nematodes (Meloidogyne spp are difficult to manage once established in the field because of their wide host range, and soil-borne nature. Thus, the aim of the present study was to examine the use of resistant root stock of wild brinjal (Solanum sisymbriifolium to reduce the loss caused by the nematodes on tomato. For the management of root-knot nematodes, grafted plant with resistant root stock of the wild brinjal was tested under farmers’ field conditions at Hemza of Kaski district. Grafted and non-grafted plants were produced in root-knot nematode-free soil. Around three week-old grafted and non-grafted tomato plants were transplanted in four different plastic tunnels where root-knot nematodes had been reported previously. The plants were planted in diagonal position to each other as a pair plot in 80 × 60 cm2 spacing in an average of 20 × 7 m2 plastic tunnels. Galling Index (GI was recorded three times in five randomly selected plants in each plot at 60 days intervals. The first observation was recorded two months after transplanting. Total fruit yield was recorded from same plants. In the grafted plants, the root system was totally free from gall whereas in an average of 7.5 GI in 0-10 scale was recorded in the non-grafted plants. Fruits were harvested from time to time and cumulated after final harvest to calculate the total fruit yield. It was estimated that on an average tomato fruit yield was significantly (P>0.05 increased by 37 percent in the grafted plants compared with the non-grafted plants. Grafting technology could be used effectively for cultivation of commonly grown varieties, which are susceptible to root-knot nematodes in disease prone areas. This can be used as an alternative technology for reducing the use of hazardous pesticides for enhancing commercial organic tomato production.
Sirca, S.; Urek, G.; Karssen, G.
The root-knot nematode Meloidogyne ethiopica Whitehead originally described from Tanzania is also distributed in South Africa, Zimbabwe, and Ethiopia (3). Although this species is a relatively unknown root-knot nematode, M. ethiopica parasitizes several economical important crops, such as tomato,
Jansson, Hans-Börje; Jeyaprakash, A.; Zuckerman, Bert M.
The endoparasitic nematophagous fungus Meria coniospora reduced root-knot nematode galling on tomatoes in greenhouse pot trials. The fungus was introduced to pots by addition of conidia at several inoculum levels directly to the soil or addition of nematodes infected with M. coniospora to the soil; both methods reduced root galling by root-knot nematodes. These studies represent a part of a recently initiated effort to evaluate the potential of endoparasitic nematophagous fungi for biocontrol...
Fassuliotis, G.; Bhatt, D. P.
Plant protoplast technology is being investigated as a means of transferring root-knot nematode resistance factors from Solanum sisymbriifolium into the susceptible S. melongena. Solanum sisymbriifolium plants regenerated from callus lost resistance to Meloidogyne javanica but retained resistance to M. incognita. Tomato plants cloned from leaf discs of the root-knot nematode resistant 'Patriot' were completely susceptible to M. incognita, while sections of stems and leaves rooted in sand in t...
Sweelam, M E [Econ. Entomology Dept., Fac. Agric. Menoufia University Shebin El-Kom, (Egypt)
The experiment was carried out at the experimental station of the faculty of agriculture, Menoufia Univ. To determine the sensitivity of root-knot nematode, Meloidogyne Javanica infecting tomato plants exposed to different doses of gamma irradiation 0,20,40,60,80 Gy, salinity levels 0. 1000, 2000, 4000 ppm and the plant growth regulator cycocel 0,200 ppm. Treated seeds were planted clay pots and salinity levels and cycocel concentrations were applied. Fresh weights and nematode populations were computed 3 months after application. Results indicated that 20 Gy, 1000 ppm salinity and cycocel gave the highest fresh weight of shoots and roots. The developmental stages and egg-laying females of nematode decreased by the increasing of irradiation dose and salinity levels. Root-knot galls decreased with 40 and 60 Gy, while significant increase was observed with 0 and 80 Gy, salinity levels decreased root galls. Cycocel decreased nematode population, egg-lying females and root-knot galls.
The experiment was carried out at the experimental station of the faculty of agriculture, Menoufia Univ. To determine the sensitivity of root-knot nematode, Meloidogyne Javanica infecting tomato plants exposed to different doses of gamma irradiation 0,20,40,60,80 Gy, salinity levels 0. 1000, 2000, 4000 ppm and the plant growth regulator cycocel 0,200 ppm. Treated seeds were planted clay pots and salinity levels and cycocel concentrations were applied. Fresh weights and nematode populations were computed 3 months after application. Results indicated that 20 Gy, 1000 ppm salinity and cycocel gave the highest fresh weight of shoots and roots. The developmental stages and egg-laying females of nematode decreased by the increasing of irradiation dose and salinity levels. Root-knot galls decreased with 40 and 60 Gy, while significant increase was observed with 0 and 80 Gy, salinity levels decreased root galls. Cycocel decreased nematode population, egg-lying females and root-knot galls
USDA ARS Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, 64 Nowelo St., Hilo, HI 96720. Root-knot nematodes cause root galling and yield reductions in many vegetable crops, including tomato. Three organic treatments to improve root growth and reduce nematode infestation were eval...
Cyst ( Globodera spp. and Heterodera spp.) and root-knot nematodes ( Meloidogyne spp.), one of the most damaging crop pests, are a perfect example of highly adapted, sophisticated root parasites. These nematodes induces specialized feeding structures (cyst
Tomato (Solanum lycopersicum) is one of the most popular vegetable crops worldwide, owing to its high nutritive value and diversified use. Tomato production in Ghana is threatened by plant parasitic nematodes, especially the root knot nematodes (Meloidogyne spp.), which are responsible for huge economic yield losses.
Indigenous strains of Trichoderma viride (ITCC No. 6889), Pseudomonas fluorescens (ITCC No. B0034) and Purpureocillium lilacinum (ITCC No.6887) were isolated from undisturbed forest eco-system of Southern India. These three bio-mediators were evaluated for their antagonism towards root knot nematode, ...
Viaene, N.; Wiseborn, D.B.; Karssen, G.
The root-knot nematode, Meloidogyne minor, was described during 2004 after it was found on potato roots in a field in the Netherlands and in golf courses in England, Wales, and Ireland (2). Since it is associated with yellow patch disease in turf grass and causes deformation of potato tubers (2), it
Edible ginger and turmeric roots are important agricultural commodities for the State of Hawaii. Bacterial wilt, Ralstonia solanacearum, and root-knot nematodes, Meloidogyne spp. are major factors hindering optimum production. An evaluation of tolerance and resistance to M. incognita was undertake...
Oka, Y.; Karssen, G.; Mor, M.
In a turfgrass nursery in Arava, Israel, a population of root-knot nematodes was isolated from poorly growing Zoysiagrass (Zoysia japonica Steud.) with symptoms of foliar chlorosis and roots with very small, smooth galls and protruding egg masses. The isolated population (genus Meloidogyne) included
Castillo, Pablo; Nico, Andrés I.; Azcón González de Aguilar, Concepción; Río Rincón, C. del; Calvet, Cinta; Jiménez-Díaz, Rafael M.
The effects were investigated, under controlled conditions, of single and joint inoculation of olive planting stocks cvs Arbequina and Picual with the arbuscular mycorrhizal fungi (AMF) Glomus intraradices, Glomus mosseae or Glomus viscosum, and the root-knot nematodes Meloidogyne incognita and Meloidogyne javanica, on plant performance and nematode infection. Establishment of the fungal symbiosis significantly increased growth of olive plants by 88·9% within a range of 11·9–214·0%, ...
Rose Rizvi; Rizwan Ali Ansari; Gulshan Zehra; Irshad Mahmood
An experiment was conducted to assess the effect of Rhizobium sp., waste tea leaves, eggshell powder, and composted cow dung manure on the root-knot nematode, Meloidogyne incognita, on lentil in Botany department AMU, Aligarh, India. When used alone, composted cow dung was better in reducing galling and nematode multiplication and improving lentil growth followed by eggshell powder, Rhizobium sp., and waste tea leaves. Significant result in the integrated management of M. incognita was obtain...
Zhu, Zhen; Chen, Fang; Xiao, Tong-jian; Wang, Xiao-hui; Ran, Wei; Yang, Xing-ming; Shen, Qi-rong
Indoor in vitro culture experiment and greenhouse pot experiment were conducted to evaluate the capabilities of three bacterial strains XZ-173 (Bacillus amyloliquefaciens), SL-25 (B. gibsonii), and KS-62 (Paenibacillus polymyxa) that can hydrolyze collagen protein in controlling tomato root-knot nematode. In the in vitro culture experiment, suspensions of XZ-173, SL-25, and KS-62 induced a mortality rate of 75.9%, 66.7%, and 50.0% to the second-stage junior nematode within 24 h, and decreased the egg hatching rate to 17.8%, 28.9% and 37.6% after 7-day incubation, respectively, in contrast to the 17.4% mortality rate and 53.6% egg hatching rate in the control (sterilized water). In the greenhouse pot experiment, the bioorganic fertilizer mixed with equal parts of fermented XZ-173, SL-25, and KS-62 gained the best result, with the root-knot nematode population in rhizosphere soil decreased by 84.0% as compared with the control. The bioorganic fertilizer also decreased the numbers of galls and eggs on tomato roots significantly, and increased the underground and aboveground biomass of tomato. Therefore, antagonist bioorganic fertilizer has promising potential in controlling root-knot nematode.
Full Text Available Pasteuria penetrans is a biological control agent of root-knot nematodes (Meloidogyne spp., preventing root invasion by second-stage juveniles (J2s, and eventually causing females sterility and death. greatest control effects for P. penetrans depend on the numbers of endospores attached to nematode cuticles. a method based on digital image analysis was used to record the effects of endospore attachment on the movements of juvenile root-knot nematodes, using a model based on the centroid point. Data showed that the numbers of endospores attached to the cuticle influenced nematode movement. At high endospore attachment levels (20‒30 per J2, nematodes did not show directional movement, whereas nematodes encumbered with five to eight spores showed limited directional movement, compared to those without endospores. nematode cephalic region turns were modelled using a markov chain, showing that P. penetrans endospores affected movements. Less nematodes invaded and established on tomato root systems when encumbered with low (five to eight or high numbers (20‒30 of P. penetrans endospores, compared with unencumbered nematodes.
Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S; Lozano-Torres, Jose L; Grundler, Florian M W; Siddique, Shahid
When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in plant-nematode interactions remain unexplored. Here, we characterized the role of a group of cell wall receptor proteins in Arabidopsis, designated as polygalacturonase-inhibiting proteins (PGIPs), during infection with the cyst nematode Heterodera schachtii and the root-knot nematode Meloidogyne incognita. PGIPs are encoded by a family of two genes in Arabidopsis, and are involved in the formation of active OG elicitors. Our results show that PGIP gene expression is strongly induced in response to cyst nematode invasion of roots. Analyses of loss-of-function mutants and overexpression lines revealed that PGIP1 expression attenuates infection of host roots by cyst nematodes, but not root-knot nematodes. The PGIP1-mediated attenuation of cyst nematode infection involves the activation of plant camalexin and indole-glucosinolate pathways. These combined results provide new insights into the molecular mechanisms underlying plant damage perception and response pathways during infection by cyst and root-knot nematodes, and establishes the function of PGIP in plant resistance to cyst nematodes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Cheng, Xingkai; Liu, Xiumei; Wang, Hongyan; Ji, Xiaoxue; Wang, Kaiyun; Wei, Min; Qiao, Kang
Southern root-knot nematode (Meloidogyne incognita) is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in labor...
A survey of 238 golf courses in ten of the Western U.S. found root-knot nematodes (Meloidogyne spp.) in 60 % of the putting greens sampled. Sequence and phylogenetic analyses of 18S rRNA, D2-D3 of 28S rRNA, ITS-rRNA and mtDNA gene sequences were used to identify specimens from 110 golf courses. The...
Luo, Hong-li; Sun, Man-hong; Xie, Jian-ping; Liu, Zhi-heng; Huang, Ying
Twenty actinomycetes were isolated from root-knot nematode eggs and females collected from 11 plant root samples infested by Meloidogyne spp.. The isolates were assigned to the genera Streptomyces, Nocardia and Pseudonocardia respectively, based on analysis of morphological characteristics, cell-wall DAPs and 16S rRNA gene sequences. 80% of them were streptomycetes. Biocontrol potential of the isolates against Meloidogyne hapla was evaluated in liquid culture in vitro. The average percentages of egg parasitism, egg hatching, and juvenile mortality were 54.1, 40.4 and 26.2, respectively. Three Streptomyces strains and one Nocardia strain with high pathogenicity in vitro were selected to determine their ability to reduce tomato root galls in greenhouse. The results demonstrated good biocontrol efficacy (31.4%-56.4%) of the strains.
Rice plantlets were randomly grown in laboratory, sprayed with hormones and riboflavin .... between riboflavin, SA, JA and ET pathways in rice-nematodes interaction, ..... oxidative damage caused by aging as well as biotic and abiotic stress.
Kiewnick, S; Sikora, R A
The egg pathogenic fungus Paecilomyces lilacinus (strain 251) is a biocontrol fungus with a potential range of activity to control the worldwide most important plant parasitic nematodes. This biological nematicide may be an useful tool in an integrated approach to control mainly sedentary nematodes. Greenhouse experiments were conducted with the root-knot nematodes Meloidogyne incognita and M. hapla on tomato. P. lilacinus, formulated as WG (BIOACT WG), was incorporated into soil inoculated with root-knot nematode eggs prior to transplanting the susceptible tomato cultivar "Hellfrucht". Furthermore, soil treatments were combined with seedling treatments 24 hours before transplanting and a soil drench 2 weeks after planting, respectively. Seedling and post planting treatment was also combined with a soil treatment at planting. All single or combination treatments tested decreased the gall index and the number of egg masses compared to the untreated control 12 weeks after planting. However, the combination of the seedling treatment with a pre- or at-planting application of P. lilacinus was necessary to achieve higher levels of control. Additional post plant drenching resulted in only a slight increase In efficacy. To the feasibility of this modified application system for the control of root-knot nematodes, a yield experiment was conducted with M. hapla and the susceptible cultivar "Gnom F1 Hybrid". It could be demonstrated that the above mentioned combination of pre-planting application plus the seedling and one post plant drench gave the best control and resulted in a significant fruit yield increase in concurrence with a decrease in number of galls per root.
Full Text Available Endoparasitic root-knot (Meloidogyne spp. and lesion (Pratylenchus spp. nematodes cause considerable damage in agriculture. Before they invade roots to complete their life cycle, soil microbes can attach to their cuticle or surface coat and antagonize the nematode directly or by induction of host plant defenses. We investigated whether the nematode-associated microbiome in soil differs between infective stages of Meloidogyne incognita and Pratylenchus penetrans, and whether it is affected by variation in the composition of microbial communities among soils. Nematodes were incubated in suspensions of five organically and two integrated horticultural production soils, recovered by sieving and analyzed for attached bacteria and fungi after washing off loosely adhering microbes. Significant effects of the soil type and nematode species on nematode-associated fungi and bacteria were revealed as analyzed by community profiling using denaturing gradient gel electrophoresis. Attached microbes represented a small specific subset of the soil microbiome. Two organic soils had very similar bacterial and fungal community profiles, but one of them was strongly suppressive towards root-knot nematodes. They were selected for deep amplicon sequencing of bacterial 16S rRNA genes and fungal ITS. Significant differences among the microbiomes associated with the two species in both soils suggested specific surface epitopes. Among the 28 detected bacterial classes, Betaproteobacteria, Bacilli and Actinobacteria were the most abundant. The most frequently detected fungal genera were Malassezia, Aspergillus and Cladosporium. Attached microbiomes did not statistically differ between these two soils. However, Malassezia globosa and four fungal species of the family Plectosphaerellaceae, and the bacterium Neorhizobium galegae were strongly enriched on M. incognita in the suppressive soil. In conclusion, the highly specific attachment of microbes to infective stages of
Olga A Postnikova
Full Text Available Nematodes are one of the major limiting factors in alfalfa production. Root-knot nematodes (RKN, Meloidogyne spp. are widely distributed and economically important sedentary endoparasites of agricultural crops and they may inflict significant damage to alfalfa fields. As of today, no studies have been published on global gene expression profiling in alfalfa infected with RKN or any other plant parasitic nematode. Very little information is available about molecular mechanisms that contribute to pathogenesis and defense responses in alfalfa against these pests and specifically against RKN. In this work, we performed root transcriptome analysis of resistant (cv. Moapa 69 and susceptible (cv. Lahontan alfalfa cultivars infected with RKN Meloidogyne incognita, widespread root-knot nematode species and a major pest worldwide. A total of 1,701,622,580 pair-end reads were generated on an Illumina Hi-Seq 2000 platform from the roots of both cultivars and assembled into 45,595 and 47,590 transcripts in cvs Moapa 69 and Lahontan, respectively. Bioinformatic analysis revealed a number of common and unique genes that were differentially expressed in susceptible and resistant lines as a result of nematode infection. Although the susceptible cultivar showed a more pronounced defense response to the infection, feeding sites were successfully established in its roots. Characteristically, basal gene expression levels under normal conditions differed between the two cultivars as well, which may confer advantage to one of the genotypes toward resistance to nematodes. Differentially expressed genes were subsequently assigned to known Gene Ontology categories to predict their functional roles and associated biological processes. Real-time PCR validated expression changes in genes arbitrarily selected for experimental confirmation. Candidate genes that contribute to protection against M. incognita in alfalfa were proposed and alfalfa-nematode interactions with
Ibrahim, S. K.; Traboulsi, A. F.
The impact of different freshly/dried chopped medicinal or aromatic plant materials as an organic amendment in pot cultures, as well as integrated with solarisation under greenhouse conditions on the root knot nematodes population was evaluated. Results indicated that application of solarisation alone gave good control (72%) but when integrated with different plant materials, the control level increased to 95% with Allium sativum and 90% with Mentha microphylla and slightly less with other plant materials which ranged from75 to 80%. The results of pot experiments revealed that the most significant effect on the number of nematodes was achieved with Tagetes patula followed by Pimpinella anisum, Melia azadirach and Origanium syriacum reaching 0.0, 1.2, 1.2 and 2.5/g of roots, respectively. Total control was obtained with Allium sativum. Origanium syriacum contained the highest amount of essential oil (6%). Results obtained indicated that integrated approach using solarisation combined with plant materials could be the best alternative control for the root-knot nematodes. (author)
The southern root-knot nematode (Meloidogyne incognita) is a major pathogen of pepper (Capsicum spp.), causing significant yield losses in heavily infected plants. The N-gene confers resistance to M. incognita, and has been successfully used to mitigate nematode damage in specific pepper varieties f...
Full Text Available Root-knot nematodes are microscopic round worms, which cause severe agricultural losses. Their attacks affect the productivity by reducing the amount and the caliber of the fruits. Chemical control is widely used, but biological control appears to be a better solution, mainly using microorganisms to reduce the quantity of pests infecting crops. Biological control is developing gradually, and with time, more products are being marketed worldwide. They can be formulated with bacteria, viruses or with filamentous fungi, which can destroy and feed on phytoparasitic nematodes. To be used by the farmers, biopesticides must be legalized by the states, which has led to the establishment of a legal framework for their use, devised by various governmental organizations.
Tushar Kanti Dutta
Full Text Available Root-knot nematodes (Meloidogyne incognita cause substantial yield losses in vegetables worldwide, and are difficult to manage. Continuous withdrawal of environmentally-harmful nematicides from the global market warrants the need for novel nematode management strategies. Utility of host-delivered RNAi has been demonstrated in several plants (Arabidopsis, tobacco and soybean that exhibited resistance against root-knot and cyst nematodes. Herein, a M. incognita-specific protease gene, cathepsin L cysteine proteinase (Mi-cpl-1, was targeted to generate tomato transgenic lines to evaluate the genetically modified nematode resistance. In vitro knockdown of Mi-cpl-1 gene led to the reduced attraction and penetration of M. incognita in tomato, suggesting the involvement of Mi-cpl-1 in nematode parasitism. Transgenic expression of the RNAi construct of Mi-cpl-1 gene resulted in 60-80% reduction in infection and multiplication of M. incognita in tomato. Evidence for in vitro and in vivo silencing of Mi-cpl-1 was confirmed by expression analysis using quantitative PCR. Our study demonstrates that Mi-cpl-1 plays crucial role during plant-nematode interaction and plant-mediated downregulation of this gene elicits detrimental effect on M. incognita development, reinforcing the potential of RNAi technology for management of phytonematodes in crop plants.
Yasuka L. Yamaguchi
Full Text Available Developmental plasticity is one of the most striking features of plant morphogenesis, as plants are able to vary their shapes in response to environmental cues. Biotic or abiotic stimuli often promote organogenesis events in plants not observed under normal growth conditions. Root-knot nematodes (RKNs are known to parasitize multiple species of rooting plants and to induce characteristic tissue expansion called galls or root-knots on the roots of their hosts by perturbing the plant cellular machinery. Galls contain giant cells (GCs and neighboring cells, and the GCs are a source of nutrients for the parasitizing nematode. Highly active cell proliferation was observed in galls. However, the underlying mechanisms that regulate the symptoms triggered by the plant-nematode interaction have not yet been elucidated. In this study, we deciphered the molecular mechanism of gall formation with an in vitro infection assay system using RKN Meloidogyne incognita, and the model plant Arabidopsis thaliana. By taking advantages of this system, we performed next-generation sequencing-based transcriptome profiling, and found that the expression of procambium identity-associated genes were enriched during gall formation. Clustering analyses with artificial xylogenic systems, together with the results of expression analyses of the candidate genes, showed a significant correlation between the induction of gall cells and procambium-associated cells. Furthermore, the promoters of several procambial marker genes such as ATHB8, TDR and WOX4 were activated not only in M. incognita-induced galls, but similarly in M. javanica induced-galls and Heterodera schachtii-induced syncytia. Our findings suggest that phytoparasitic nematodes modulate the host’s developmental regulation of the vascular stem cells during gall formation.
Yamaguchi, Yasuka L; Suzuki, Reira; Cabrera, Javier; Nakagami, Satoru; Sagara, Tomomi; Ejima, Chika; Sano, Ryosuke; Aoki, Yuichi; Olmo, Rocio; Kurata, Tetsuya; Obayashi, Takeshi; Demura, Taku; Ishida, Takashi; Escobar, Carolina; Sawa, Shinichiro
Developmental plasticity is one of the most striking features of plant morphogenesis, as plants are able to vary their shapes in response to environmental cues. Biotic or abiotic stimuli often promote organogenesis events in plants not observed under normal growth conditions. Root-knot nematodes (RKNs) are known to parasitize multiple species of rooting plants and to induce characteristic tissue expansion called galls or root-knots on the roots of their hosts by perturbing the plant cellular machinery. Galls contain giant cells (GCs) and neighboring cells, and the GCs are a source of nutrients for the parasitizing nematode. Highly active cell proliferation was observed in galls. However, the underlying mechanisms that regulate the symptoms triggered by the plant-nematode interaction have not yet been elucidated. In this study, we deciphered the molecular mechanism of gall formation with an in vitro infection assay system using RKN Meloidogyne incognita , and the model plant Arabidopsis thaliana. By taking advantages of this system, we performed next-generation sequencing-based transcriptome profiling, and found that the expression of procambium identity-associated genes were enriched during gall formation. Clustering analyses with artificial xylogenic systems, together with the results of expression analyses of the candidate genes, showed a significant correlation between the induction of gall cells and procambium-associated cells. Furthermore, the promoters of several procambial marker genes such as ATHB8 , TDR and WOX4 were activated not only in M. incognita -induced galls, but similarly in M. javanica induced-galls and Heterodera schachtii -induced syncytia. Our findings suggest that phytoparasitic nematodes modulate the host's developmental regulation of the vascular stem cells during gall formation.
Pradeep Kumar Papolu
Full Text Available Root-knot nematodes (RKN cause substantial yield decline in eggplant and sustainable management options to minimize crop damage due to nematodes are still limited. A number of genetic engineering strategies have been developed to disrupt the successful plant-nematode interactions. Among them, delivery of proteinase inhibitors from the plant to perturb nematode development and reproduction is arguably the most effective strategy. In the present study, transgenic eggplant expressing a modified rice cystatin (OC-IΔD86 gene under the control of the root-specific promoter, TUB-1, was generated to evaluate the genetically modified nematode resistance. Five putative transformants were selected through PCR and genomic Southern blot analysis. Expression of the cystatin transgene was confirmed in all the events using western blotting, ELISA and qPCR assay. Upon challenge inoculation, all the transgenic events exhibited a detrimental effect on RKN development and reproduction. The best transgenic line (a single copy event showed 78.3% inhibition in reproductive success of RKN. Our results suggest that cystatins can play an important role for improving nematode resistance in eggplant and their deployment in gene pyramiding strategies with other proteinase inhibitors could ultimately enhance crop yield.
Jada, M. Y.; Gungula, D. T.; Jacob, I.
Bambara groundnut (Vigna subterrenea L. Verdc.) is an important crop produced in Adamawa State of Nigeria. However, the production of the crop is seriously threatened by root-knot nematodes (RKNs; Meloidogyne spp.). Since cultural methods have not been very effective in controlling RKN, carbofuran was evaluated to determine its efficacy in controlling M. javanica in Yola during 2002 and 2003. Three bambara groundnut cultivars (Kwachanjiwa, Kwaheuma, and Kwatolotolo) were evaluated using three...
Hyoung Rai Ko
Full Text Available To investigate occurrence of root-knot nematode (RKN in plastic house of central area of Korea, 132 soil samples were collected in cucumber, water melon, tomato, red pepper and strawberry fields from 2013 to 2015. Among 132 soil samples, 65 soil samples (49% were infested with RKN and mean density of RKN was 178 second-stage juveniles per 100 cm³ soil (min. 1 ~ max. 3,947. The frequency of RKN by regional was the highest in Chuncheon with 80%, followed by Cheonan (68%, Nonsan (36%, Buyeo (33% and Yesan (30%. The frequency of RKN by crops was the highest in tomato with 83%, followed by cucumber (61%, strawberry (41%, red pepper (30%, watermelon (26%. To identify the species of RKN, fifteen populations were selected for representative populations. As a phylogenetic analysis of 15 populations, southern root-knot nematode (Meloidogyne incognita, peanut root-knot nematode (M. arenaria and northern root-knot nematode (M. hapla were identified with 47%, 20% and 33% ratio, respectively. In crops, M. incognita, M. arenaria and M. hapla were detected in tomato, M. incognita and M. arenaria were detected in cucumber and watermelon, and M. hapla was detected in strawberry and lettuce. Thus, there should be a continuous management to major species of each crops to prevent dispersal of RKN damages.
Pasteuria penetrans is a parasite of root-knot nematode (Meloidogyne spp.). Spores of P. penetrans attach to the cuticle of second stage juvenile (J2) and sterilize infected female. This study looked at different factors that influence spore attachment of P. penetrans to M. arenaria. Incubating J2 ...
Carneiro, R.M.D.G.; Correa, V.R.; Almeida, M.R.A.; Gomes, A.C.M.M.; Deimi, A.M.; Castagnone-Sereno, P.; Karssen, G.
A new root-knot nematode parasitising vegetables, flowers and fruits in Brazil, Iran and Chile, is described as Meloidogyne luci n. sp. The female has an oval to squarish perineal pattern with a low to moderately high dorsal arc and without shoulders, similar to M. ethiopica. The female stylet is
Root knot nematodes (Meloidogyne spp., RKN) can negatively impact both herbaceous annual and woody perennial hosts. RKN infestations also may increase plant host susceptibility to other stresses such as those imposed by water deficits or various diseases. However, little is known about direct or ind...
Davies, K G; Rowe, J A; Williamson, V M
Specific host-parasite interactions exist between species and strains of plant parasitic root-knot nematodes and the Gram-positive bacterial hyperparasite Pasteuria penetrans. This bacterium produces endospores that adhere to the cuticle of migrating juveniles, germinate and colonise the developing female within roots. Endospore attachment of P. penetrans populations to second-stage juveniles of the root-knot nematode species Meloidogyne incognita and Meloidogyne hapla showed there were interactive differences between bacterial populations and nematode species. Infected females of M. incognita produced a few progeny which were used to establish two nematode lines from single infective juveniles encumbered with either three or 26 endospores. Single juvenile descent lines of each nematode species were produced to test whether cuticle variation was greater within M. hapla lines that reproduce by facultative meiotic parthenogenesis than within lines of M. incognita, which reproduces by obligate parthenogenesis. Assays revealed variability between broods of individual females derived from single second-stage juvenile descent lines of both M. incognita and M. hapla suggesting that progeny derived from a single individual can differ in spore adhesion in both sexual and asexual nematode species. These results suggest that special mechanisms that produced these functional differences in the cuticle surface may have evolved in both sexually and asexually reproducing nematodes as a strategy to circumvent infection by this specialised hyperparasite.
Fernando E. eDíaz-Manzano
Full Text Available Root-knot nematodes (RKN are polyphagous plant-parasitic roundworms that produce large crop losses, representing a relevant agricultural pest worldwide. After infection, they induce swollen root structures called galls containing giant cells (GCs indispensable for nematode development. Among efficient control methods are biotechnology-based strategies that require a deep knowledge of underlying molecular processes during the plant-nematode interaction. Methods of achieving this knowledge include the application of molecular biology techniques such as transcriptomics (massive sequencing or microarray hybridization, proteomics or metabolomics. These require aseptic experimental conditions, as undetected contamination with other microorganisms could compromise the interpretation of the results. Herein, we present a simple, efficient and long-term method for nematode amplification on cucumber roots grown in vitro. Amplification of juveniles (J2 from the starting inoculum is around 40-fold. The method was validated for three Meloidogyne species (M. javanica, M. incognita and M. arenaria, producing viable and robust freshly hatched J2s. These can be used for further in vitro infection of different plant species such as Arabidopsis, tobacco and tomato, as well as enough J2s to maintain the population. The method allowed maintenance of around 90 Meloidogyne spp. generations (one every two months from a single initial female over 15 years.
Smiljana Goreta Ban
Full Text Available The aim of this study was to determine the effect of rootstocks on the growth and yield of cucumber (Cucumis sativus L. plants in soils infested with root-knot nematodes (Meloidogyne spp. Cucumber 'Adrian' was grown with its own roots or was grafted onto three rootstocks of Lagenariasiceraria (Molina Standi. ('Emphasis', 'S-1', and 'Gourd', two interspecific hybrid rootstocks of Cucurbita maxima Duchesne x C. moschata Duchesne ('Strong Tosa' and 'RS 841 Improved' and zucchini Cucurbita pepo L. ('Romanesco Zucchini'. The experiments were conducted in commercial greenhouse, with cucumber grafted onto three rootstocks in the first season and onto six rootstocks in the second spring-summer season. The number of leaves was considerably affected by the rootstock in both seasons, and was the highest for the plants grafted onto interspecific rootstocks (28.0 in the first and 44.9 in the second season. The plants grafted onto 'Strong Tosa' had higher total number of fruits (19.9 and yield (5.38 kg compared to other rootstocks or non-grafted plants in first season, and the same result was found for two interspecific rootstocks in the second season (6.96 kg and more than 28.9 fruits per plant. The total soluble solids, pH and electrical conductivity of the fruit were not affected by rootstock, while titratable acidity changed with the rootstock type. The grafting of cucumber plants onto different rootstocks was confirmed as an acceptable non-chemical method to compete with the limitations of soils infected with root-knot nematodes, but the effect was highly dependent on the choice of the rootstock.
Qiu, Jinya Jack; Westerdahl, Becky B; Pryor, Alan
Ozone gas (O₃) is a reactive oxidizing agent with biocidal properties. Because of the current phasing out of methyl bromide, investigations on the use of ozone gas as a soil-fumigant were conducted. Ozone gas was produced at a concentration of 1% in air by a conventional electrical discharge O₃ generator. Two O₃ dosages and three gas flow rates were tested on a sandy loam soil collected from a tomato field that had a resident population of root knot nematodes, Meloidogyne javanica. At dosages equivalent to 50 and 250 kg of O₃/ha, M. javanica were reduced by 24% and 68%, and free-living nematodes by 19% and 52%, respectively. The reduction for both M. javanica and free-living nematodes was dosage dependent and flow rate independent. The rates of O₃ mass transfer (OMT) through three soils of different texture were greater at low and high moisture levels than at intermediate ones. At any one soil moisture level, the OMT rate varied with soil texture and soil organic matter content. Results suggest that soil texture, moisture, and organic matter content should be considered in determining O₃ dosage needed for effective nematode control.
Full Text Available Suppression of root-knot nematodes is crucially important for maintaining the worldwide development of the banana industry. Growing concerns about human and environmental safety have led to the withdrawal of commonly used nematicides and soil fumigants, thus motivating the development of alternative nematode management strategies. In this study, Meloidogyne javanica was isolated, and the nematicidal effect of Camellia seed cake on this pest was investigated. The results showed that in dish experiments, Camellia seed cake extracts under low concentration (2 g/L showed a strong nematicidal effect. After treatment for 72 h, the eggs of M. javanica were gradually dissolved, and the intestine of the juveniles gradually became indistinct. Nematicidal compounds, including saponins identified by HPLC-ESI-MS and 8 types of volatile compounds identified by GC-MS, exhibited effective nematicidal activities, especially 4-methylphenol. The pot experiments demonstrated that the application of Camellia seed cake suppressed M. javanica, and promoted the banana plant growth. This study explored an effective nematicidal agent for application in soil and revealed its potential mechanism of nematode suppression.
Desaeger, J A; Csinos, A S
Combination treatments of chisel-injected fumigants (methyl bromide, 1,3-D, metam sodium, and chloropicrin) on a first crop, followed by drip-applied fumigants (metam sodium and 1,3-D +/- chloropicrin) on a second crop, with and without oxamyl drip applications were evaluated for control of Meloidogyne incognita in three different tests (2002 to 2004) in Tifton, GA. First crops were eggplant or tomato, and second crops were cantaloupe, squash, or jalapeno pepper. Double-cropped vegetables suffered much greater root-knot nematode (RKN) pressure than first crops, and almost-total yield loss occurred when second crops received no nematicide treatment. On a first crop of eggplant, all fumigants provided good nematode control and average yield increases of 10% to 15 %. On second crops, higher application rates and fumigant combinations (metam sodium and 1,3-D +/- chloropicrin) improved RKN control and increased yields on average by 20% to 35 % compared to the nonfumigated control. Oxamyl increased yields of the first crop in 2003 on average by 10% to 15% but had no effect in 2004 when RKN failed to establish itself. On double-cropped squash in 2003, oxamyl following fumigation provided significant additional reduction in nematode infection and increased squash yields on average by 30% to 75%.
Full Text Available An experiment was conducted to assess the effect of Rhizobium sp., waste tea leaves, eggshell powder, and composted cow dung manure on the root-knot nematode, Meloidogyne incognita, on lentil in Botany department AMU, Aligarh, India. When used alone, composted cow dung was better in reducing galling and nematode multiplication and improving lentil growth followed by eggshell powder, Rhizobium sp., and waste tea leaves. Significant result in the integrated management of M. incognita was obtained when Rhizobium sp. was used in combination with cow dung and eggshell powder (with or without waste tea leaves. Combined application of root nodule bacterium and organic wastes like waste tea leaves, eggshell, and cow dung may be suggested to the farmers/growers or related persons who are having great enthusiasm to establish a lentil production business. Application of these organic materials along with the root nodule bacteria may be helpful to foster soil ecosystem which has been a hot topic in the present scenario.
Wei, Lihui; Shao, Ying; Wan, Jingwang; Feng, Hui; Zhu, Hua; Huang, Huiwen; Zhou, Yijun
The rhizobacterial strain Jdm2 was isolated from the rhizosphere of the traditional Chinese medicinal herb Trichosanthes kirilowii in Jiangsu province, China, and was identified as Bacillus subtilis. Exposure of cell-free filtrate of the strain to the root-knot nematode Meloidogyne incognita under in vitro conditions caused substantial mortality of the second stage juvenile (J2) and significantly reduced egg hatchability. A greenhouse trial demonstrated that 56 days after treatment with Jdm2, the number of galls associated with M. incognita infection in the tomato (Solanum lycopersicum) roots was significantly reduced compared to controls, and the disease severity of infected plants was lower in treated plants (36%) compared to water control (75%). Consistently, in the field trial, the biocontrol efficacy of Jdm2 reached 69%, 51% and 48% after 30, 60 and 90 days post-transplantation, respectively. As indicated by PCR-DGGE analysis, inoculation with Jdm2 strain had an effect on the bacterial community of the tomato rhizosphere at the first stage, but was not able to imperil the bacterial community stability for long time. The novel bacterial strain Jdm2 enhances plant growth and inhibits nematode activity, and has the potential to be a safe and effective microbial pesticide.
Full Text Available The rhizobacterial strain Jdm2 was isolated from the rhizosphere of the traditional Chinese medicinal herb Trichosanthes kirilowii in Jiangsu province, China, and was identified as Bacillus subtilis. Exposure of cell-free filtrate of the strain to the root-knot nematode Meloidogyne incognita under in vitro conditions caused substantial mortality of the second stage juvenile (J2 and significantly reduced egg hatchability. A greenhouse trial demonstrated that 56 days after treatment with Jdm2, the number of galls associated with M. incognita infection in the tomato (Solanum lycopersicum roots was significantly reduced compared to controls, and the disease severity of infected plants was lower in treated plants (36% compared to water control (75%. Consistently, in the field trial, the biocontrol efficacy of Jdm2 reached 69%, 51% and 48% after 30, 60 and 90 days post-transplantation, respectively. As indicated by PCR-DGGE analysis, inoculation with Jdm2 strain had an effect on the bacterial community of the tomato rhizosphere at the first stage, but was not able to imperil the bacterial community stability for long time. The novel bacterial strain Jdm2 enhances plant growth and inhibits nematode activity, and has the potential to be a safe and effective microbial pesticide.
Sari, D. I. P.; Lisnawita; Oemry, S.; Safni, I.; Lubis, K.; Tantawi, A. R.
Root knot nematode (Meloidogyne spp.) is one of the important pathogens that causes big impact on potato crop yields. One of the control strategies for controlling this nematode is the use of biofumigants. Biofumigants are volatile toxic compound derived from plants, and have biocide properties against insects and plant pathogens. Organic waste such as Brassicaceae, Leguminoceae, and Solanaceae can be used as biofumigant sources. This research was conducted to determine the effectiveness of Brassicaceae, Leguminoceae, and Solanaceae as biofumigants against Meloidogyne spp. The experiment was set in a completely randomized design (CRD) with the treatments were organic wastes including Brassicaceae, Leguminoceae, and Solanaceae, both single and combinations, and 2 controls (positive and negative controls) with 3 replications. Each of the biofumigant treatments was prepared and stored for 2 weeks. Potato tubers were transplanted 15 days after germination into polybag inoculated with 1,000 Meloidogyne spp. J2s. The results showed that Brassicaceae + Solanaceae were effective in decreasing the number of galls in potato plants, however only Solanaceae improved plant growth.
Utari, E.; Lisnawita; Safni, I.; Lubis, K.; Tantawi, AR; Hasanuddin
The root knot nematode (Meloidogyne spp.) is one of important pathogens on potato crops in North Sumatra, Indonesia. This nematode causes significant crop losses on potatoes directly and indirectly. The effect of fungal isolates (Trichoderma sp. 1, Mucor sp.1, Aspergillus sp. 2, Mucor sp. 2) that were isolated from rhizosphere of potato in North Sumatra were studied in green house experiments on the growth of potato and the reproduction of the nematode (Meloidogyne spp). The results showed that Trichoderma sp. 1 caused a significant gall reduction, while Mucor sp.1 and Mucor sp.2 could improve the growth of potato.
Cheng, Xingkai; Liu, Xiumei; Wang, Hongyan; Ji, Xiaoxue; Wang, Kaiyun; Wei, Min; Qiao, Kang
Southern root-knot nematode (Meloidogyne incognita) is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in laboratory, greenhouse and field trials. Laboratory results showed that emamectin benzoate exhibited high toxicity to M. incognita, with LC50 and LC90 values 3.59 and 18.20 mg L(-1), respectively. In greenhouse tests, emamectin benzoate soil application offered good efficacy against M. incognita while maintaining excellent plant growth. In field trials, emamectin benzoate provided control efficacy against M. incognita and resulted in increased tomato yields. Compared with the untreated control, there was a 36.5% to 81.3% yield increase obtained from all treatments and the highest yield was received from the highest rate of emamectin benzoate. The results confirmed that emamectin benzoate has enormous potential for the control of M. incognita in tomato production in China.
Full Text Available Southern root-knot nematode (Meloidogyne incognita is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in laboratory, greenhouse and field trials. Laboratory results showed that emamectin benzoate exhibited high toxicity to M. incognita, with LC50 and LC90 values 3.59 and 18.20 mg L(-1, respectively. In greenhouse tests, emamectin benzoate soil application offered good efficacy against M. incognita while maintaining excellent plant growth. In field trials, emamectin benzoate provided control efficacy against M. incognita and resulted in increased tomato yields. Compared with the untreated control, there was a 36.5% to 81.3% yield increase obtained from all treatments and the highest yield was received from the highest rate of emamectin benzoate. The results confirmed that emamectin benzoate has enormous potential for the control of M. incognita in tomato production in China.
Zhu, Ming Liang; Mo, Ming He; Xia, Zhen Yuan; Li, Yun Hua; Yang, Shu Jun; Li, Tian Fei; Zhang, Ke Qin
The strain ZK7 of Pochonia chlamydosporia var. chlamydosporia and IPC of Paecilomyces lilacinus are highly effective in the biological control against root-knot nematodes infecting tobacco. When applied, they require a specific monitoring method to evaluate the colonization and dispersal in soil. In this work, the randomly amplified polymorphic DNA (RAPD) technique was used to differentiate between the two individual strains and 95 other isolates, including isolates of the same species and common soil fungi. This approach allowed the selection of specific fragments of 1.2 kb (Vc1200) and 2.0 kb (Vc2000) specific for ZK7, 1.4 kb (P1400) and 0.85 kb (P850) specific for IPC, using the random Primers OPL-02, OPD-05, OPD-05 and OPC-11, respectively. These fragments were cloned, sequenced, and used to design sequence-characterized amplification region (SCAR) primers specific for the two strains. In classical polymerase chain reaction (PCR), with serial dilution of ZK7 and IPC pure culture DNAs template, the detection limits of these oligonucleotide SCAR-PCR primers were found to be 10, 1000, 500, 100 pg, respectively. In the dot blotting, digoxigenin (DIG)-labeled amplicons from these four primers specifically recognized the corresponding fragments in the DNAs template of these two strains. The detection limit of these amplicons were 0.2, 0.2, 0.5, 0.5 mug, respectively.
Full Text Available The root-knot nematode (RKN, Meloidogyne incognita, is an obligate, sedentary endoparasite that infects a large number of crops and severely affects productivity. The commonly used nematode control strategies have their own limitations. Of late, RNA interference (RNAi has become a popular approach for the development of nematode resistance in plants. Transgenic crops capable of expressing dsRNAs, specifically in roots for disrupting the parasitic process, offer an effective and efficient means of producing resistant crops. We identified nematode-responsive and root-specific (NRRS promoters by using microarray data from the public domain and known conserved cis-elements. A set of 51 NRRS genes was identified which was narrowed down further on the basis of presence of cis-elements combined with minimal expression in the absence of nematode infection. The comparative analysis of promoters from the enriched NRRS set, along with earlier reported nematode-responsive genes, led to the identification of specific cis-elements. The promoters of two candidate genes were used to generate transgenic plants harboring promoter GUS constructs and tested in planta against nematodes. Both promoters showed preferential expression upon nematode infection, exclusively in the root in one and galls in the other. One of these NRRS promoters was used to drive the expression of splicing factor, a nematode-specific gene, for generating host-delivered RNAi-mediated nematode-resistant plants. Transgenic lines expressing dsRNA of splicing factor under the NRRS promoter exhibited upto a 32% reduction in number of galls compared to control plants.
Full Text Available The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.
Adam, Mohamed; Heuer, Holger; Hallmann, Johannes
The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.
Thies, Judy A; Ariss, Jennifer J; Kousik, Chandrasekar S; Hassell, Richard L; Levi, Amnon
Southern root-knot nematode (RKN, Meloidogyne incognita) is a serious pest of cultivated watermelon (Citrullus lanatus var. lanatus) in southern regions of the United States and no resistance is known to exist in commercial watermelon cultivars. Wild watermelon relatives (Citrullus lanatus var. citroides) have been shown in greenhouse studies to possess varying degrees of resistance to RKN species. Experiments were conducted over 2 yr to assess resistance of southern RKN in C. lanatus var. citroides accessions from the U.S. Watermelon Plant Introduction Collection in an artificially infested field site at the U.S. Vegetable Laboratory in Charleston, SC. In the first study (2006), 19 accessions of C. lanatus var. citroides were compared with reference entries of Citrullus colocynthis and C. lanatus var. lanatus. Of the wild watermelon accessions, two entries exhibited significantly less galling than all other entries. Five of the best performing C. lanatus var. citroides accessions were evaluated with and without nematicide at the same field site in 2007. Citrullus lanatus var. citroides accessions performed better than C. lanatus var. lanatus and C. colocynthis. Overall, most entries of C. lanatus var. citroides performed similarly with and without nematicide treatment in regard to root galling, visible egg masses, vine vigor, and root mass. In both years of field evaluations, most C. lanatus var. citroides accessions showed lesser degrees of nematode reproduction and higher vigor and root mass than C. colocynthis and C. lanatus var. lanatus. The results of these two field evaluations suggest that wild watermelon populations may be useful sources of resistance to southern RKN.
José Dijair Antonino de Souza Junior
Full Text Available Root-knot nematodes induce galls that contain giant-feeding cells harboring multiple enlarged nuclei within the roots of host plants. It is recognized that the cell cycle plays an essential role in the set-up of a peculiar nuclear organization that seemingly steers nematode feeding site induction and development. Functional studies of a large set of cell cycle genes in transgenic lines of the model host Arabidopsis thaliana have contributed to better understand the role of the cell cycle components and their implication in the establishment of functional galls. Mitotic activity mainly occurs during the initial stages of gall development and is followed by an intense endoreduplication phase imperative to produce giant-feeding cells, essential to form vigorous galls. Transgenic lines overexpressing particular cell cycle genes can provoke severe nuclei phenotype changes mainly at later stages of feeding site development. This can result in chaotic nuclear phenotypes affecting their volume. These aberrant nuclear organizations are hampering gall development and nematode maturation. Herein we report on two nuclear volume assessment methods which provide information on the complex changes occurring in nuclei during giant cell development. Although we observed that the data obtained with AMIRA tend to be more detailed than Volumest (Image J, both approaches proved to be highly versatile, allowing to access 3D morphological changes in nuclei of complex tissues and organs. The protocol presented here is based on standard confocal optical sectioning and 3-D image analysis and can be applied to study any volume and shape of cellular organelles in various complex biological specimens. Our results suggest that an increase in giant cell nuclear volume is not solely linked to increasing ploidy levels, but might result from the accumulation of mitotic defects.
Santos, Jansen Rodrigo Pereira; Ndeve, Arsenio Daniel; Huynh, Bao-Lam; Matthews, William Charles; Roberts, Philip Alan
Cowpea is one of the most important food and forage legumes in drier regions of the tropics and subtropics. However, cowpea yield worldwide is markedly below the known potential due to abiotic and biotic stresses, including parasitism by root-knot nematodes (Meloidogyne spp., RKN). Two resistance genes with dominant effect, Rk and Rk2, have been reported to provide resistance against RKN in cowpea. Despite their description and use in breeding for resistance to RKN and particularly genetic mapping of the Rk locus, the exact genes conferring resistance to RKN remain unknown. In the present work, QTL mapping using recombinant inbred line (RIL) population 524B x IT84S-2049 segregating for a newly mapped locus and analysis of the transcriptome changes in two cowpea near-isogenic lines (NIL) were used to identify candidate genes for Rk and the newly mapped locus. A major QTL, designated QRk-vu9.1, associated with resistance to Meloidogyne javanica reproduction, was detected and mapped on linkage group LG9 at position 13.37 cM using egg production data. Transcriptome analysis on resistant and susceptible NILs 3 and 9 days after inoculation revealed up-regulation of 109 and 98 genes and down-regulation of 110 and 89 genes, respectively, out of 19,922 unique genes mapped to the common bean reference genome. Among the differentially expressed genes, four and nine genes were found within the QRk-vu9.1 and QRk-vu11.1 QTL intervals, respectively. Six of these genes belong to the TIR-NBS-LRR family of resistance genes and three were upregulated at one or more time-points. Quantitative RT-PCR validated gene expression to be positively correlated with RNA-seq expression pattern for eight genes. Future functional analysis of these cowpea genes will enhance our understanding of Rk-mediated resistance and identify the specific gene responsible for the resistance.
Jansen Rodrigo Pereira Santos
Full Text Available Cowpea is one of the most important food and forage legumes in drier regions of the tropics and subtropics. However, cowpea yield worldwide is markedly below the known potential due to abiotic and biotic stresses, including parasitism by root-knot nematodes (Meloidogyne spp., RKN. Two resistance genes with dominant effect, Rk and Rk2, have been reported to provide resistance against RKN in cowpea. Despite their description and use in breeding for resistance to RKN and particularly genetic mapping of the Rk locus, the exact genes conferring resistance to RKN remain unknown. In the present work, QTL mapping using recombinant inbred line (RIL population 524B x IT84S-2049 segregating for a newly mapped locus and analysis of the transcriptome changes in two cowpea near-isogenic lines (NIL were used to identify candidate genes for Rk and the newly mapped locus. A major QTL, designated QRk-vu9.1, associated with resistance to Meloidogyne javanica reproduction, was detected and mapped on linkage group LG9 at position 13.37 cM using egg production data. Transcriptome analysis on resistant and susceptible NILs 3 and 9 days after inoculation revealed up-regulation of 109 and 98 genes and down-regulation of 110 and 89 genes, respectively, out of 19,922 unique genes mapped to the common bean reference genome. Among the differentially expressed genes, four and nine genes were found within the QRk-vu9.1 and QRk-vu11.1 QTL intervals, respectively. Six of these genes belong to the TIR-NBS-LRR family of resistance genes and three were upregulated at one or more time-points. Quantitative RT-PCR validated gene expression to be positively correlated with RNA-seq expression pattern for eight genes. Future functional analysis of these cowpea genes will enhance our understanding of Rk-mediated resistance and identify the specific gene responsible for the resistance.
ABD EL FATTAH, A.I.; KAMEL, H.A.; EL-NAGDI, W.M.A.
The main objective of this study was to investigate the effect of irradiation of sugar beet seeds on the plant resistance to root-knot nematode Meloidogyne incognita infection in addition to some morphological parameters, biochemical components and root technological characters. Relative to control (non-irradiated seeds), the obtained data showed that, all doses except 10 Gy significantly increased root length of un inoculated plants and the most effective dose was 200 Gy. All doses significantly decreased root diameter except 50 and 100 Gy. The 10 and 400 Gy significantly reduced root fresh weight while 50, 100 and 200 Gy caused non-significant increase. All doses significantly increased root fresh weight/dry weight than control. There was non-significant effect on the morphological parameters of the plants germinated from gamma irradiated seeds and inoculated with Meloidogyne incognita. Total chlorophyll of seed irradiated and un inoculated plants were significantly reduced by all doses except 200 Gy. All doses of gamma radiation caused non-significant decrease in the total chlorophyll of the infected plants. In un inoculated plants, a significant reduction in the total phenol was occurred due to all doses of gamma radiation. In contrast, in inoculated plants, 10 and 25 Gy caused significant reduction in the total phenol while 50 and 400 Gy caused significant increase in the total phenol.Significant increase in sucrose % was observed due to 10 Gy in the un inoculated plants. The 400 Gy caused significant decrease while other doses caused non-significant decrease in the sucrose %. In the inoculated plants, 50, 100 and 400 Gy caused significant increase in sucrose %. All doses significantly increased total soluble salts percent (TSS %) of either inoculated or un inoculated plants. Purity % was increased by all doses in the inoculated plants.The number of galls and egg masses were reduced gradually by increasing gamma doses and 100 Gy caused the highest reduction 89
Gamal El-Din Abd El Kader Y
Full Text Available Abstract Background Root-knot nematodes are sedentary endoparasites that can infect more than 3000 plant species. Root-knot nematodes cause an estimated $100 billion annual loss worldwide. For successful establishment of the root-knot nematode in its host plant, it causes dramatic morphological and physiological changes in plant cells. The expression of some plant genes is altered by the nematode as it establishes its feeding site. Results We examined the expression of soybean (Glycine max genes in galls formed in roots by the root-knot nematode, Meloidogyne incognita, 12 days and 10 weeks after infection to understand the effects of infection of roots by M. incognita. Gene expression was monitored using the Affymetrix Soybean GeneChip containing 37,500 G. max probe sets. Gene expression patterns were integrated with biochemical pathways from the Kyoto Encyclopedia of Genes and Genomes using PAICE software. Genes encoding enzymes involved in carbohydrate and cell wall metabolism, cell cycle control and plant defense were altered. Conclusions A number of different soybean genes were identified that were differentially expressed which provided insights into the interaction between M. incognita and soybean and into the formation and maintenance of giant cells. Some of these genes may be candidates for broadening plants resistance to root-knot nematode through over-expression or silencing and require further examination.
Full Text Available Introduction: Biocontrol of nematode agents in order to decrease the hazardous impacts of chemical pesticide application including problems of public health and environmental pollution is apriority. In this study, solid (Vermicompost and liquid products (Liquid Vermicompost, Vermiwash and Coelomic fluidof the earthworm species Eisenia fetida were tested against root-knot nematode, Meloidogyne javanica in greenhouse conditions. Materials and Methods: In this study, Solid (Vermicompost and Liquid products(Wormtea, Vermiwash, Coelomic fluid erthworms (Eisenia foetida were tested against Meloidogyne javanica and also the effect of Vermicompost was evaluated on Pathogenicity of various nematode initial inoculum in two stage greenhouse conditions. Earthworm-based products (Vermicompost, Wormtea, Vermiwash and Coelomic fluid were added to tomato pots. Various treatments of liquid as well as solid products and their combination were used in the greenhouse trial. The first Stage greenhouse experiment- Tomato seeds grown in 2 kg sterilized soil. In the treatments having Vermicompost, pots incorporated with 200 gr of this compost homogeneously mixed with soil. After plants reached at two leaf stage, to study the effects of liquid products (Wormtea, Vermiwash, and Coelomic fluid they added to the pots (500cc along with the irrigation water every week and after of 4 leaf stage, 5000 nematode eggs and larva inoculated to the tomato host plants. 90 days after nematode inoculation, plant and nematode growth indices separately measured and compared. The experiment conducted based on completely randomized design having four replicates. The second stage greenhouse experiment- Tomato seeds grown in 2 kg sterilized soil. In the treatments, pots incorporated with 200 gr of this compost homogeneously mixed with soil. After of 4 leaf stage, 0,1000,2000,4000 and 10000 nematode eggs and larva inoculated to the tomato host plants. 90 days after nematode inoculation, plant
Rapid identification of cyst (Heterodera spp., Globodera spp.) and root-knot (Meloidogyne spp.) nematodes on the basis of ITS2 sequence variation detected by PCR-single-strand conformational polymorphism (PCR-SSCP) in cultures and field samples
Clapp, J.P.; Van der Stoel, C.D.; Van der Putten, W.H.
Cyst and root-knot nematodes show high levels of gross morphological similarity. This presents difficulties for the study of their ecology in natural ecosystems. In this study, cyst and root-knot nematode species, as well as some ectoparasitic nematode species, were identified using the second
Siddiqui, Imran Ali; Haas, Dieter; Heeb, Stephan
In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocon...
Siddiqui, Imran Ali; Haas, Dieter; Heeb, Stephan
In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocontrol. PMID:16151170
Vos, Christine; Geerinckx, Katleen; Mkandawire, Rachel; Panis, Bart; De Waele, Dirk; Elsen, Annemie
The root-knot nematode Meloidogyne incognita poses a worldwide threat to agriculture, with an increasing demand for alternative control options since most common nematicides are being withdrawn due to environmental concerns. The biocontrol potential of arbuscular mycorrhizal fungi (AMF) against plant-parasitic nematodes has been demonstrated, but the modes of action remain to be unraveled. In this study, M. incognita penetration of second-stage juveniles at 4, 8 and 12 days after inoculation was compared in tomato roots (Solanum lycopersicum cv. Marmande) pre-colonized or not by the AMF Glomus mosseae. Further life stage development of the juveniles was also observed in both control and mycorrhizal roots at 12 days, 3 weeks and 4 weeks after inoculation by means of acid fuchsin staining. Penetration was significantly lower in mycorrhizal roots, with a reduction up to 32%. Significantly lower numbers of third- and fourth-stage juveniles and females accumulated in mycorrhizal roots, at a slower rate than in control roots. The results show for the first time that G. mosseae continuously suppresses root-knot nematodes throughout their entire early infection phase of root penetration and subsequent life stage development.
Cabrera, Javier; Olmo, Rocio; Ruiz-Ferrer, Virginia; Hermans, Christian; Martinez-Argudo, Isabel; Escobar, Carolina
Most effective nematicides for the control of root-knot nematodes are banned, which demands a better understanding of the plant-nematode interaction. Understanding how gene expression in the nematode-feeding sites relates to morphological features may assist a better characterization of the interaction. However, nematode-induced galls resulting from cell-proliferation and hypertrophy hinders such observation, which would require tissue sectioning or clearing. We demonstrate that a method based on the green auto-fluorescence produced by glutaraldehyde and the tissue-clearing properties of benzyl-alcohol/benzyl-benzoate preserves the structure of the nematode-feeding sites and the plant-nematode interface with unprecedented resolution quality. This allowed us to obtain detailed measurements of the giant cells’ area in an Arabidopsis line overexpressing CHITINASE-LIKE-1 (CTL1) from optical sections by confocal microscopy, assigning a role for CTL1 and adding essential data to the scarce information of the role of gene repression in giant cells. Furthermore, subcellular structures and features of the nematodes body and tissues from thick organs formed after different biotic interactions, i.e., galls, syncytia, and nodules, were clearly distinguished without embedding or sectioning in different plant species (Arabidopsis, cucumber or Medicago). The combination of this method with molecular studies will be valuable for a better understanding of the plant-biotic interactions. PMID:29389847
Noreen, R.; Shafique, A.; Haque, S.E.; Ali, S.A.
Three isolates each of fluorescent Pseudomonas (NAFP-19, NAFP-31 and NAFP-32) and rhizobia (NFB- 103, NFB-107 and NFB-109) which were originally isolated from root nodules of mungbean (Vigna radiata) showed significant biocontrol activity in the screen house and under field condition, against root rotting fungi viz., Macrophomina phaseolina, Fusarium solani, F. oxysporum and Rhizoctonia solani evaluated on chickpea. Biocontrol potential of these isolates was also evaluated against Meloidogyne incognita, the root knot nematode. Application of Pseudomonas and rhizobial isolates as a soil drench, separately or mixed significantly reduced root rot disease under screen house and field conditions. Nematode penetration in roots was also found significantly less in rhizobia or Pseudomonas treatments used separately or mixed as compared to control. Fluorescent Pseudomonas treated plants produced greater number of nodules per plant than control plants and about equal to rhizobia treated plants, indicating that root nodule associated fluorescent Pseudomonas enhance root nodulation. (author)
Ajjappala, Hemavathi; Chung, Ha Young; Sim, Joon-Soo; Choi, Inchan; Hahn, Bum-Soo
The aim of this study is to demonstrate the feasibility of down-regulating endogeneous prefoldin-2 root-knot nematode transcripts by expressing dsRNA with sequence identity to the nematode gene in tobacco roots under the influence of strong Arabidopsis ubiquitin (UBQ1) promoter. Root-knot nematodes (RKNs) are sedentary endoparasites infecting a wide range of plant species. They parasitise the root system, thereby disrupting water and nutrient uptake and causing major reductions in crop yields. The most reliable means of controlling RKNs is via the use of soil fumigants such as methyl bromide. With the emergence of RNA interference (RNAi) technology, which permits host-mediated nematode gene silencing, a new strategy to control plant pathogens has become available. In the present study, we investigated host-induced RNAi gene silencing of prefoldin-2 in transgenic Nicotiana benthamiana. Reductions in prefoldin-2 mRNA transcript levels were observed when nematodes were soaked in a dsRNA solution in vitro. Furthermore, nematode reproduction was suppressed in RNAi transgenic lines, as evident by reductions in the numbers of root knots (by 34-60 % in independent RNAi lines) and egg masses (by 33-58 %). Endogenous expression of prefoldin-2, analysed via real-time polymerase chain reaction and Western blotting, revealed that the gene was strongly expressed in the pre-parasitic J2 stage. Our observations demonstrate the relevance and potential importance of targeting the prefoldin gene during the nematode life cycle. The work also suggests that further improvements in silencing efficiency in economically important crops can be accomplished using RNAi directed against plant-parasitic nematodes.
Wieczorek, K; Elashry, A; Quentin, M; Grundler, F M W; Favery, B; Seifert, G J; Bohlmann, H
Pectin in the primary plant cell wall is thought to be responsible for its porosity, charge density, and microfibril spacing and is the main component of the middle lamella. Plant-parasitic nematodes secrete cell wall-degrading enzymes that macerate the plant tissue, facilitating the penetration and migration within the roots. In sedentary endoparasitic nematodes, these enzymes are released only during the migration of infective juveniles through the root. Later, nematodes manipulate the expression of host plant genes, including various cell wall enzymes, in order to induce specific feeding sites. In this study, we investigated expression of two Arabidopsis pectate lyase-like genes (PLL), PLL18 (At3g27400) and PLL19 (At4g24780), together with pectic epitopes with different degrees of methylesterification in both syncytia induced by the cyst nematode Heterodera schachtii and giant cells induced by the root-knot nematode Meloidogyne incognita. We confirmed upregulation of PLL18 and PLL19 in both types of feeding sites with quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ RT-PCR. Furthermore, the functional analysis of mutants demonstrated the important role of both PLL genes in the development and maintenance of syncytia but not giant cells. Our results show that both enzymes play distinct roles in different infected root tissues as well as during parasitism of different nematodes.
Youssef, Reham M; MacDonald, Margaret H; Brewer, Eric P; Bauchan, Gary R; Kim, Kyung-Hwan; Matthews, Benjamin F
The gene encoding PAD4 (PHYTOALEXIN-DEFICIENT4) is required in Arabidopsis for expression of several genes involved in the defense response to Pseudomonas syringae pv. maculicola. AtPAD4 (Arabidopsis thaliana PAD4) encodes a lipase-like protein that plays a regulatory role mediating salicylic acid signaling. We expressed the gene encoding AtPAD4 in soybean roots of composite plants to test the ability of AtPAD4 to deter plant parasitic nematode development. The transformed roots were challenged with two different plant parasitic nematode genera represented by soybean cyst nematode (SCN; Heterodera glycines) and root-knot nematode (RKN; Meloidogyne incognita). Expression of AtPAD4 in soybean roots decreased the number of mature SCN females 35 days after inoculation by 68 percent. Similarly, soybean roots expressing AtPAD4 exhibited 77 percent fewer galls when challenged with RKN. Our experiments show that AtPAD4 can be used in an economically important crop, soybean, to provide a measure of resistance to two different genera of nematodes.
Major quantitative trait loci (QTL) have been mapped to Upland cotton (Gossypium hirsutum L.) chromosomes 11 and 14 that govern the highly resistant phenotype in response to infection by root-knot nematode (RKN; Meloidogyne incognita Chitwood & White); however, nearly nothing is known regarding the ...
We investigated DNA sequencing information from alleles (DNA amplified fragments) of two previously reported SSR markers (CIR316 and MUCS088) linked to root-knot nematode (RKN) resistance genes. Markers based on electrophoretic differences, including RFLPs, AFLPs and SSRs can sometimes mask underlyi...
Karssen, G.; Bolk, R.J.; Aelst, van A.C.; Beld, van den I.; Kox, L.F.F.; Korthals, G.W.; Molendijk, L.P.G.; Zijlstra, C.; Hoof, van R.A.; Cook, R.
A relatively small root-knot nematode, Meloidogyne minor n. sp., is described and illustrated from tomato from the Netherlands. This new species is characterised by the following features: female with dorsally curved stylet, 14 Pm long, with transversely ovoid knobs slightly sloping backwards from
M. Y. Jada
Full Text Available Bambara groundnut (Vigna subterrenea L. Verdc. is an important crop produced in Adamawa State of Nigeria. However, the production of the crop is seriously threatened by root-knot nematodes (RKNs; Meloidogyne spp.. Since cultural methods have not been very effective in controlling RKN, carbofuran was evaluated to determine its efficacy in controlling M. javanica in Yola during 2002 and 2003. Three bambara groundnut cultivars (Kwachanjiwa, Kwaheuma, and Kwatolotolo were evaluated using three application timings (at planting, 3 and 6 weeks after planting, and none. Results indicated that applying carbofuran at planting provided the greatest reduction in M. javanica population levels, which lead to increased yields in bambara groundnuts compared to the other two application timings. Furthermore, both Kwachanjiwa and Kwatolotolo provided similar high yields compared to Kwaheuma, which was most likely related to the M. javanica tolerance in these cultivars.
Etienne G J Danchin
Full Text Available Root-knot nematodes are globally the most aggressive and damaging plant-parasitic nematodes. Chemical nematicides have so far constituted the most efficient control measures against these agricultural pests. Because of their toxicity for the environment and danger for human health, these nematicides have now been banned from use. Consequently, new and more specific control means, safe for the environment and human health, are urgently needed to avoid worldwide proliferation of these devastating plant-parasites. Mining the genomes of root-knot nematodes through an evolutionary and comparative genomics approach, we identified and analyzed 15,952 nematode genes conserved in genomes of plant-damaging species but absent from non target genomes of chordates, plants, annelids, insect pollinators and mollusks. Functional annotation of the corresponding proteins revealed a relative abundance of putative transcription factors in this parasite-specific set compared to whole proteomes of root-knot nematodes. This may point to important and specific regulators of genes involved in parasitism. Because these nematodes are known to secrete effector proteins in planta, essential for parasitism, we searched and identified 993 such effector-like proteins absent from non-target species. Aiming at identifying novel targets for the development of future control methods, we biologically tested the effect of inactivation of the corresponding genes through RNA interference. A total of 15 novel effector-like proteins and one putative transcription factor compatible with the design of siRNAs were present as non-redundant genes and had transcriptional support in the model root-knot nematode Meloidogyne incognita. Infestation assays with siRNA-treated M. incognita on tomato plants showed significant and reproducible reduction of the infestation for 12 of the 16 tested genes compared to control nematodes. These 12 novel genes, showing efficient reduction of parasitism when
The products of parasitism genes in nematodes must be secreted to reach their targets at the nematode-plant interface. These nematode secretory proteins are therefore recognised to play an important role in the nematode-plant interaction and as a result have been subject of intense study for years.
Dwi Sri Hastuti, Liana; Faull, Jane
A pot experiment was carried out to test the effectiveness of nematode-trapping fungi (NTF) isolated from Sumatera for controlling infection by the root-knot nematode (RKN) on Deli tobacco plant. Wheat bran soil containing 109 conidia of Arthrobotrys. oligospora, Candellabrella musiformis and Dactylella eudermata was added to the soil as a dry inoculum. Carbofuran was also applied as chemical agent and comparison treatment. Seedling tobacco (Nicotiana tabacum L.) cv. Deli 4 was inoculated with root knot (Meloidogyne incognita Chitwood.) seven days after the plant were transplanted to the pots. A. oligospora, C. musiformis and D. eudermata were found to be reliable as biocontrol agents, reducing the number of vermiform nematodes, swollen root, sausage shaped and galls in tobacco plant after 7, 15 and 30 days of infection with M. incognita. Treatment with NTF produced results that were comparable with Carbofuran® as a control agent in the reduction of the number of infections in tobacco plant caused by M. incognita in Nicotiana tabacum var. Deli 4. They also optimize the growth of the tobacco plants especially up to 15 days after infection.
Bhau, B S; Borah, Bitupon; Ahmed, Reshma; Phukon, P; Gogoi, Barbi; Sarmah, D K; Lal, M; Wann, S B
Plants adapt themselves to overcome adverse environmental conditions, and this involves a plethora of concurrent cellular activities. Physiological experiments or metabolic profiling can quantify this response. Among several diseases of Pogostemon cablin (Blanco) Benth. (Patchouli), root-knot nematode infection caused by Meloidogyne incognita (Kofoid and White) Chitwood causes severe damage to the plant and hence, the oil production. In the present study, we identified M. incognita morphologically and at molecular level using sequenced characterized amplified region marker (SCAR). M. incognita was artificially inoculated at different levels of second stage juveniles (J₂) to examine the effect on Patchouli plant growth parameters. Peroxidase and polyphenol oxidase enzyme activity and changes in the total phenol and chlorophyll contents in M. incognita was also evaluated in response to infection. The results have demonstrated that nematode infestation leads to increased peroxidase activities in the leaves of the patchouli plants and thereby, increase in phenolic content as a means of defence against nematode infestation. Chlorophyll content was also found decreased but no changes in polyphenol oxidase enzyme activity.
Full Text Available Efficiency of an organic matter like Tagetes erecta and bioinoculants Azotobacter chroococcum and Glomus fasciculatum was investigated in tomato cultivar ‘Pusa Ruby’ when inoculated individually as well as concomitantly for the management of the root-knot nematode, Meloidogyne incognita in terms of growth parameters such as plant length, fresh and dry weights, chlorophyll content, per cent pollen fertility and mycorrhization. Greatest reduction in the numbers of second-stage juveniles in soil, number of root-galls, egg-masses and nematode multiplication was recorded with combined application of T. erecta and bio-inoculants A. chroococcum and G. fasciculatum as compared to untreated control and other treatments. Similarly, the greatest improvement in the plant growth and biomass of tomato was noted in the same treatments. However, individual inoculation of these bio-inoculants and organic fertilizers also showed significant enhancement but was less as compared to combined treatment. A. chroococcum was found most effective against disease incidence followed by G. fasciculatum and T. erecta. Parameters like NP and K contents were significantly enhanced in those plants which received combined treatments of organic matter and bio-inoculants. Azotobacter was found more efficacious against nematodes than Glomus fasciculatum. Organic matter also influenced the activity of bio-inoculants, more with the Azotobacter than G. fasciculatum. DOI: http://dx.doi.org/10.3126/ije.v4i2.12643 International Journal of Environment Vol.4(2 2015: 206-220
Full Text Available The use of biological control agents could be a non-chemical alternative for management of Meloidogyne spp. [root-knot nematodes (RKN], the most damaging plant-parasitic nematodes for horticultural crops worldwide. Pochonia chlamydosporia is a fungal parasite of RKN eggs that can colonize endophytically roots of several cultivated plant species, but in field applications the fungus shows a low persistence and efficiency in RKN management. The combined use of P. chlamydosporia with an enhancer could help its ability to develop in soil and colonize roots, thereby increasing its efficiency against nematodes. Previous work has shown that chitosan enhances P. chlamydosporia sporulation and production of extracellular enzymes, as well as nematode egg parasitism in laboratory bioassays. This work shows that chitosan at low concentrations (up to 0.1 mg ml-1 do not affect the viability and germination of P. chlamydosporia chlamydospores and improves mycelial growth respect to treatments without chitosan. Tomato plants irrigated with chitosan (same dose limit increased root weight and length after 30 days. Chitosan irrigation increased dry shoot and fresh root weight of tomato plants inoculated with Meloidogyne javanica, root length when they were inoculated with P. chlamydosporia, and dry shoot weight of plants inoculated with both P. chlamydosporia and M. javanica. Chitosan irrigation significantly enhanced root colonization by P. chlamydosporia, but neither nematode infection per plant nor fungal egg parasitism was affected. Tomato plants cultivated in a mid-suppressive (29.3 ± 4.7% RKN egg infection non-sterilized clay loam soil and irrigated with chitosan had enhanced shoot growth, reduced RKN multiplication, and disease severity. Chitosan irrigation in a highly suppressive (73.7 ± 2.6% RKN egg infection sterilized-sandy loam soil reduced RKN multiplication in tomato. However, chitosan did not affect disease severity or plant growth irrespective of
Full Text Available An experiment was conducted to observe the effect of fly ash on hatching, mortality and penetration of root-knot nematode (Meloidogyne incognita in pumpkin roots. For hatching experiment different fly ash-extract concentrations (5, 10, 20, 30, 40, and 50% were prepared. Hatching was significantly reduced in all concentrations, maximum being at 50% concentration. The mortality (% of juveniles was observed in 1, 2, 3, 4, 5, 6 and 7th days with different levels (5, 10, 20, 30, 40 and 50 % of fly ash-extract. All the levels were found harmful to juveniles. As the level was increased, the killing percentage of juveniles was also increased. Highest mortality was observed in 7th day with 50% level.For the penetration experiment, fly ash was mixed with soil to prepare different concentrations (5, 10, 20, 30, 40, and 50%. Seeds of pumpkin were grown in coffee cups filled with different mixtures. At two leaf stage, seedlings were inoculated with 2000 larvae. The penetrated larvae in roots were observed after 1, 2, 3, 4, 5, 6 and 7 days. Root penetration was found inversely proportional to concentration. Significant results in the suppression of nematode penetration were noted up to 40% concentration. However, none of the juveniles was penetrated at 50% concentration.International Journal of Environment Vol.5(3 2016, pp.66-73
Atkins, Simon D; Hidalgo-Diaz, Leopoldo; Clark, Ian M; Morton, C Oliver; de Oca, Nivian Montes; Gray, Paul A; Kerry, Brian R
Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. beta-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.
Kapur-Ghai, J; Kaur, M; Goel, P
Root-knot nematodes (Meloidogyne incognita) are obligate, sedentary plant endoparasites that are extremely polyphagous in nature and cause severe economic losses in agriculture. Hence, it is essential to control the parasite at an early stage. For any control strategy to be effective, an early and accurate diagnosis is of paramount importance. Immunoassays have the inherent advantages of sensitivity and specificity; have the potential to identify and quantify these plant-parasitic nematodes. Hence, in the present studies, enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of M.incognita antigens. First an indirect ELISA was developed for detection and titration of anti-M.incognita antibodies. Results indicated as high as 320 K titre of the antisera. Finally competitive inhibition ELISA was developed employing these anti-M.incognita antibodies for detection of M.incognita antigens. Sensitivity of ELISA was 10 fg. Competitive inhibition ELISA developed in the present studies has the potential of being used as an easy, rapid, specific and sensitive diagnostic tool for the detection of M.incognita infection.
P. E. V. Aguiar
Full Text Available Mato Grosso is the third largest producer of bean from Brazil, being the third harvest (irrigated the most productive, but diseases such as anthracnose, web blight and nematodes of galls cause losses to producers. In addition, a measure widely used and little studied for the control of diseases and nematodes in Mato Grosso is the biological control, which consists of the action of other microorganisms on phytopathogens. Thus, the objective of the present study was to evaluate the effect of Trichoderma harzianum and T. asperellum in the development (height of plants, chlorophyll and number of pods of culture of bean, in the control of anthracnose (Colletotrichum lindemuthianum, web blight (Rhizoctonia solani and in the population of Meloidogyne spp. in the soil. The experiment was accomplished in area experimental of University Federal of Mato Grosso/Campus Sinop. The experimental design was of entirely randomized with 12 parcels of 5m² each, with 3 treatments and 4 replications. The cultivar used was Whitey, carioca group, and the seed treatment performed with product Pyraclostrobin + Thiophanate Methyl + Fipronil and after drying of the inoculation of biocontrol agents and manual seeding. It was observed that the application of T. harzianum and T. asperellum, not promoted increase of chlorophyll, height of plants in bean culture, without reducing the population of Meloidogyne spp.. However, biocontrol agents have reduced the severity of anthracnose and web blight and promoted an increase in the average number of plant pods-1. It is therefore concluded that biocontrol agents show potential for application in bean culture in the North of Mato Grosso.
Adomako, J.; Kwoseh, C. K.
The increased concern for environmental and health hazards have called for a reduction in the use of synthetic nematicides for nematode control. Experiments were, therefore, conducted to ascertain the nematicidal potential of castor bean's crude extract and its five lower concentrations with water as control. In the in vitro studies, crude castor bean aqueous extract and 10, 20, 30 and 40% different concentrations with 100 root-knot nematode eggs or juveniles in separate Petri dishes showed that all the different concentrations had toxic effects on eggs and juveniles of root-knot nematode. Egg hatch inhibition and juvenile mortality increased with increased concentration of the extracts. With an increase in exposure time, juvenile mortality increased. In potted plant studies, crude castor bean aqueous extracts and its lower concentrations of 20, 40 and 60% caused significant improvement in plant growth measures such as height and fresh shoot weight over the water blank control. The crude castor bean extract was nematotoxic to root -knot nematodes in vitro and in potted-tomato plants, but this was not demonstrated in field studies. Further work needs to be done before a firm recommendation can be made. (au)
Zhang, Si-Hui; Lian, Jian-Hong; Cao, Zhi-Ping; Zhao, Li
A field experiment with successive planting of tomato was conducted to study the effects of adding different amounts of winter wheat straw (2.08 g x kg(-1), 1N; 4.16 g x kg(-1), 2N; and 8.32 g x kg(-1), 4N) to the soil seriously suffered from root knot nematode disease on the soil microbial biomass and protozoa abundance. Adding straw carbon source had significant effects on the contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the abundance of soil protozoa, which all decreased in the order of 4N > 2N > 1N > CK. The community structure of soil protozoa also changed significantly under straw addition. In the treatments with straw addition, the average proportion of fagellate, amoeba, and ciliates accounted for 36.0%, 59.5%, and 4.5% of the total protozoa, respectively. Under the same adding amounts of wheat straw, there was an increase in the soil MBC and MBN contents, MBC/MBN ratio, and protozoa abundance with increasing cultivation period.
Full Text Available The root-knot nematode Meloidogyne ulmi is synonymised with Meloidogyne mali based on morphological and morphometric similarities, common hosts, as well as biochemical similarities at both protein and DNA levels. M. mali was first described in Japan on Malus prunifolia Borkh.; and M. ulmi in Italy on Ulmus chenmoui W.C. Cheng. Morphological and morphometric studies of their holo- and paratypes revealed important similarities in the major characters as well as some general variability in a few others. Host test also showed that besides the two species being able to parasitize the type hosts of the other, they share some other common hosts. Our study of the esterase and malate dehydrogenase isozyme phenotypes of some M. ulmi populations gave a perfectly comparable result to that already known for M. mali. Finally, phylogenetic studies of their SSU and LSU rDNA sequence data revealed that the two are not distinguishable at DNA level. All these put together, leave strong evidences to support the fact that M. ulmi is not a valid species, but a junior synonym of M. mali. Brief discussion on the biology and life cycle of M. mali is given. An overview of all known hosts and the possible distribution of M. mali in Europe are also presented.
Rybarczyk-Mydłowska, Katarzyna; Maboreke, Hazel Ruvimbo; van Megen, Hanny; van den Elsen, Sven; Mooyman, Paul; Smant, Geert; Bakker, Jaap; Helder, Johannes
Plant parasitic nematodes are unusual Metazoans as they are equipped with genes that allow for symbiont-independent degradation of plant cell walls. Among the cell wall-degrading enzymes, glycoside hydrolase family 5 (GHF5) cellulases are relatively well characterized, especially for high impact parasites such as root-knot and cyst nematodes. Interestingly, ancestors of extant nematodes most likely acquired these GHF5 cellulases from a prokaryote donor by one or multiple lateral gene transfer events. To obtain insight into the origin of GHF5 cellulases among evolutionary advanced members of the order Tylenchida, cellulase biodiversity data from less distal family members were collected and analyzed. Single nematodes were used to obtain (partial) genomic sequences of cellulases from representatives of the genera Meloidogyne, Pratylenchus, Hirschmanniella and Globodera. Combined Bayesian analysis of ≈ 100 cellulase sequences revealed three types of catalytic domains (A, B, and C). Represented by 84 sequences, type B is numerically dominant, and the overall topology of the catalytic domain type shows remarkable resemblance with trees based on neutral (= pathogenicity-unrelated) small subunit ribosomal DNA sequences. Bayesian analysis further suggested a sister relationship between the lesion nematode Pratylenchus thornei and all type B cellulases from root-knot nematodes. Yet, the relationship between the three catalytic domain types remained unclear. Superposition of intron data onto the cellulase tree suggests that types B and C are related, and together distinct from type A that is characterized by two unique introns. All Tylenchida members investigated here harbored one or multiple GHF5 cellulases. Three types of catalytic domains are distinguished, and the presence of at least two types is relatively common among plant parasitic Tylenchida. Analysis of coding sequences of cellulases suggests that root-knot and cyst nematodes did not acquire this gene directly
Full Text Available Abstract Background Plant parasitic nematodes are unusual Metazoans as they are equipped with genes that allow for symbiont-independent degradation of plant cell walls. Among the cell wall-degrading enzymes, glycoside hydrolase family 5 (GHF5 cellulases are relatively well characterized, especially for high impact parasites such as root-knot and cyst nematodes. Interestingly, ancestors of extant nematodes most likely acquired these GHF5 cellulases from a prokaryote donor by one or multiple lateral gene transfer events. To obtain insight into the origin of GHF5 cellulases among evolutionary advanced members of the order Tylenchida, cellulase biodiversity data from less distal family members were collected and analyzed. Results Single nematodes were used to obtain (partial genomic sequences of cellulases from representatives of the genera Meloidogyne, Pratylenchus, Hirschmanniella and Globodera. Combined Bayesian analysis of ≈ 100 cellulase sequences revealed three types of catalytic domains (A, B, and C. Represented by 84 sequences, type B is numerically dominant, and the overall topology of the catalytic domain type shows remarkable resemblance with trees based on neutral (= pathogenicity-unrelated small subunit ribosomal DNA sequences. Bayesian analysis further suggested a sister relationship between the lesion nematode Pratylenchus thornei and all type B cellulases from root-knot nematodes. Yet, the relationship between the three catalytic domain types remained unclear. Superposition of intron data onto the cellulase tree suggests that types B and C are related, and together distinct from type A that is characterized by two unique introns. Conclusions All Tylenchida members investigated here harbored one or multiple GHF5 cellulases. Three types of catalytic domains are distinguished, and the presence of at least two types is relatively common among plant parasitic Tylenchida. Analysis of coding sequences of cellulases suggests that root-knot
Wiratno,; Taniwiryono, D.; Berg, van den J.H.J.; Riksen, J.A.G.; Rietjens, I.; Djiwanti, S.R.; Kammenga, J.E.; Murk, A.J.
Nematicidal activity of extracts from plants was assayed against Meloidogyne incognita. In laboratory assays extracts from tobacco (Nicotiana tabacum L), clove (Syzygium aromaticum L), betelvine (Piper betle L), and sweet flag (Acorus calamus L) were most effective in killing the nematode, with an
Synthetic chemicals have been used to control plant pathogenic nematodes in the farmers fields. These chemicals, though valued for their effectiveness, are costly and may constitute health hazards to farm households and the environment. Reducing these situations in the farms through use of natural plant extracts is one of ...
Dowd, Carola D; Chronis, Demosthenis; Radakovic, Zoran S; Siddique, Shahid; Schmülling, Thomas; Werner, Tomáš; Kakimoto, Tatsuo; Grundler, Florian M W; Mitchum, Melissa G
Cyst and root-knot nematodes are obligate parasites of economic importance with a remarkable ability to reprogram root cells into unique metabolically active feeding sites. Previous studies have suggested a role for cytokinin in feeding site formation induced by these two types of nematodes, but the mechanistic details have not yet been described. Using Arabidopsis as a host plant species, we conducted a comparative analysis of cytokinin genes in response to the beet cyst nematode (BCN), Heterodera schachtii, and the root-knot nematode (RKN), Meloidogyne incognita. We identified distinct differences in the expression of cytokinin biosynthesis, catabolism and signaling genes in response to infection by BCN and RKN, suggesting differential manipulation of the cytokinin pathway by these two nematode species. Furthermore, we evaluated Arabidopsis histidine kinase receptor mutant lines ahk2/3, ahk2/4 and ahk3/4 in response to RKN infection. Similar to our previous studies with BCN, these lines were significantly less susceptible to RKN without compromising nematode penetration, suggesting a requirement of cytokinin signaling in RKN feeding site formation. Moreover, an analysis of ahk double mutants using CycB1;1:GUS/ahk introgressed lines revealed contrasting differences in the cytokinin receptors mediating cell cycle activation in feeding sites induced by BCN and RKN. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.
Yu, Ziquan; Xiong, Jing; Zhou, Qiaoni; Luo, Haiyan; Hu, Shengbiao; Xia, Liqiu; Sun, Ming; Li, Lin; Yu, Ziniu
Cry6A toxin from Bacillus thuringiensis is a representative nematicidal crystal protein with a variety of nematicidal properties to free-living nematode Caenorhabditis elegans. Cry6A shares very low homology and different structure with Cry5B, another representative nematicidal crystal protein, and probably acts in a distinct pathway. All these strongly indicate that Cry6A toxin is likely a potent candidate for nematicide. The present study dealt with global investigation to determine the detrimental impacts of Cry6Aa2 toxin on Meloidogyne hapla, a root-knot nematode, and evaluated its biocontrol efficacy in pot experiment. Obtained results indicated that Cry6Aa2 toxin exhibits obvious toxicity to second-stage juvenile of M. hapla, and significantly inhibits egg hatch, motility, and penetration to host plant. Pot experiment suggested that soil drenching with spore-crystal mixture of Cry6Aa2 can clearly lighten the disease of root-knot nematode, including reduction of galling index and egg masses on host plant root, decreasing final population of nematode in soil. Moreover, application of Cry6Aa2 can obviously promote plant growth. These results demonstrated that Cry6Aa2 toxin is a promising nematicidal agent, and possesses great potential in plant-parasitic nematode management and construction of transgenic crop with constant resistance to nematode. Copyright © 2015 Elsevier Inc. All rights reserved.
Full Text Available Introduction: Root-knot nematodes (Meloidogyne spp. are important plant pathogens that make large damage to the crops. The activity of root-knot nematode and reaction of host plant results in the development of several knots on the root, which interrupts water and food absorption system of the plant. Among popular methods for controlling root-knot nematodes are physical methods (soil solarization and flooding, farming methods (crop rotation, weed removal, contaminated roots removal, fertilization, soil reinforcement, planting time adjustment, and use of resistant varieties, and chemical methods (disinfection with pesticide and foliar spray. Incomplete control, high cost and environmental problems (chemical compounds have directed some researchers toward to use non-chemical methods such as herbs and herbal products for the management nematodes. Mankind has used medicinal plants throughout the history in both direct and indirect ways. Today, medicinal plants have a considerable share of medical products. The nematicidal effect of many plants has been demonstrated and the use of plant products has been considered as a safe method to control root-knot nematode. This method is cheap and easy to use, does not cause environmental pollution, and is able to improve the soil in structural and nutritional terms. Organic plants possess a wide range of secondary metabolites such as phenyls, flavonoids, coinons, tanons, essences, alkaloids, saponins, and sterols. These substances are biodegradable owing to their natural origin and do not pollute the environment. Today, active plant compounds are given much attention because they are less durable and do not have the negative impact on mammals and non-target organisms. Plant products including essences and extracts are usually used to control plant diseases nematodes. Therefore, due to the favorable impact of plants in controlling Root-knot nematodes, In this study, the presence of several herbs (thyme, hyssop
Abou El-Atta, Doaa Abd El-Maksoud; Ghazy, Noureldin Abuelfadl; Osman, Mohamed Ali
Sancassania (Caloglyphus) berlesei (Michael) is a cosmopolitan and free-living mite that inhabits soil as well as laboratory colonies of insects and fungi and may have a role as a biocontrol agent of nematodes. In this study, we investigated the effects of temperature on the development, reproduction, and food consumption of S. berlesei fed egg masses of root-knot nematodes, Meloidogyne spp., an important group of agricultural pests. Mites were reared at 20, 25 or 30 °C in the dark. The mites could feed on the nematode egg masses, and their developmental time decreased at higher temperatures. Time from the egg to adult was similar in females and males reared at the same temperature. Adult females lived longer than males at 25 °C, but not at 20 or 30 °C. Generally, females showed a higher rate of food consumption than males. Females laid the largest number of eggs at 20 and 25 °C (199.7 and 189.8 eggs/female, respectively), but the intrinsic rate of natural increase was highest at 30 °C (r m = 0.29). In comparing our data with previous reports, we noted that S. berlesei that fed on egg masses of root-knot nematodes showed a longer developmental time and a lower reproductive rate than Sancassania mites that fed on other diets. Nonetheless, the relatively high value of r m (e.g., at 25 and 30 °C) suggests that this mite may have certain advantages as a biocontrol agent of root-knot nematodes.
Francisco José Carvalho Moreira
Full Text Available The correct identification of species and genus of nematodes that affect a particular culture is of great importance to form a quantity of information that will be useful to laboratories for diagnosis and control of these pathogens. Because of the increase in the production of ornamental and medicinal plants in the of Cear. á State, the agricultural importance of the genus Meloidogyne and the scarcity of information on the hospitability this pathogen in these species, in that it was to evaluate the susceptibility testing of 30 species, and 20 ornamental (Antirrhimum majus, Gazania ringens, Carthamus tinctorius, Bryophyllum cayicinum, Ceasalpinia pulcherrima, Thumbergia alata, Petunia hibryda, Exacum affine, Catharanthus roseus, Opuntia sp., Sansevieria trifasciata, Asparagus densiflorus, Hibiscus mutabilis-roreus, Impatiens balsamiana, Celosia spicata, Antirrhimum sp., Dianthus chinensis, Zinnia elegans, Tagetes patula, Capsicum annuum and 10 medicinal (Peumus boldus, Ocimum gratissimum, Mentha arvensis var. piperascens, Mentha x Vilosa, Plectranthus amboinicus, Ocimum bassilicum, Rosmarinus officinalis, Cymbopogon citratus, Lippia alba, Cymbopogon winterianus. The test was conducted in a greenhouse, of the Phytosanitary Sector, Department of Plant Science, Federal University of Ceará. The inoculation was conducted with 4,000 eggs/J2 for pot. Evaluation of the plants gave to 60 days after inoculation. Evaluated is the reaction of the plants, measuring up: number of galls and eggs, egg mass index, reproduction factor and reduce the reproduction factor. From these variables it was classified the reaction of plants to the nematode by means of five criterions. Of ownership of the results, it was verified that of the ornamental plants only species T. patula didn’t presented galls in your root system. Concerning medicinal species M. vilosa, C. citrates, L. alba, C. winterianus and P. boldus showed no galls in their root systems. Thus, concluded
López-Gómez, M.; Verdejo-Lucas, S.
Meloidogyne javanica has showed less reproductive success than M. incognita in watermelon genotypes. This study was conducted to elucidate the low reproduction of M. javanica in watermelon. The post-infection development of M. javanica in watermelon ‘Sugar Baby’ was determined at progressively higher initial population (Pi) levels at two time points during the life cycle. Plants were inoculated with 0, 25, 50, 100, 200, and 300 second-stage juveniles (J2)/plant. The increase in Pi was correlated with the penetration rates (R2= 0.603, p<0.001) and total numbers of nematodes in the root (R2 =0.963, p< 0.001) but there was no correlation between the Pi and the reproduction factor (eggs/plant/Pi). The population in the roots at 26 days post-inoculation (dpi) consisted primarily of third-stage juveniles (J3) with a small presence of J2 and fourth stages, and egg-laying females. The dominance of the J3, when egg-laying females are expected, point to the malfunction of the feeding sites that failed to support nematode development beyond the J3 stage. The similarities in egg-laying females at 26 and 60 dpi imply the disruption of the life cycle. Watermelon compensated for M. javanica parasitism by increasing vine length (19% to 33%) and dry top weight (40%) in comparison with the non-inoculated plants. The area under the vine length progress curve was significantly larger as the Pi progressively increased (R²=0.417, p<0.001). Physiological variation was detected between the M. incognita populations. M. arenaria had less ability to invade watermelon roots than did M. incognita and M. javanica.
Transcriptome analysis of root-knot nematode (Meloidogyne incognita)-infected tomato (Solanum lycopersicum) roots reveals complex gene expression profiles and metabolic networks of both host and nematode during susceptible and resistance responses
Shukla, Neha; Yadav, Rachita; Kaur, Pritam
Root knot nematodes (RKNs, Meloidogyne incognita) are economically important endoparasites having a wide-host range. We have taken a comprehensive transcriptomic approach to investigate the expression of both tomato and RKN genes in tomato roots at five infection time intervals from susceptible p...
Transcriptome analysis of root-knot nematode (Meloidogyne incognita)-infected tomato (Solanum lycopersicum) roots reveals complex gene expression profiles and metabolic networks of both host and nematode during susceptible and resistance responses
Shukla, Neha; Yadav, Rachita; Kaur, Pritam
Root knot nematodes (RKNs, Meloidogyne incognita) are economically important endoparasites having a wide-host range. We have taken a comprehensive transcriptomic approach to investigate the expression of both tomato and RKN genes in tomato roots at five infection time intervals from susceptible p...
Giné, Ariadna; Carrasquilla, Marc; Martínez-Alonso, Maira; Gaju, Núria; Sorribas, Francisco J
The fluctuation of Meloidogyne population density and the percentage of fungal egg parasitism were determined from July 2011 to July 2013 in two commercial organic vegetable production sites (M10.23 and M10.55) in plastic greenhouses, located in northeastern Spain, in order to know the level of soil suppressiveness. Fungal parasites were identified by molecular methods. In parallel, pot tests characterized the level of soil suppressiveness and the fungal species growing from the eggs. In addition, the egg parasitic ability of 10 fungal isolates per site was also assessed. The genetic profiles of fungal and bacterial populations from M10.23 and M10.55 soils were obtained by Denaturing Gradient Gel Electrophoresis (DGGE), and compared with a non-suppressive soil (M10.33). In M10.23, Meloidogyne population in soil decreased progressively throughout the rotation zucchini, tomato, and radish or spinach. The percentage of egg parasitism was 54.7% in zucchini crop, the only one in which eggs were detected. Pochonia chlamydosporia was the only fungal species isolated. In M10.55, nematode densities peaked at the end of the spring-summer crops (tomato, zucchini, and cucumber), but disease severity was lower than expected (0.2-6.3). The percentage of fungal egg parasitism ranged from 3 to 84.5% in these crops. The results in pot tests confirmed the suppressiveness of the M10.23 and M10.55 soils against Meloidogyne. The number of eggs per plant and the reproduction factor of the population were reduced (P < 0.05) in both non-sterilized soils compared to the sterilized ones after one nematode generation. P. chlamydosporia was the only fungus isolated from Meloidogyne eggs. In in vitro tests, P. chlamydosporia isolates were able to parasitize Meloidogyne eggs from 50 to 97% irrespective of the site. DGGE fingerprints revealed a high diversity in the microbial populations analyzed. Furthermore, both bacterial and fungal genetic patterns differentiated suppressive from non
Full Text Available The fluctuation of Meloidogyne population density and the percentage of fungal egg parasitism were determined from July 2011 to July 2013 in two commercial organic vegetable production sites (M10.23 and M10.55 in plastic greenhouses, located in northeastern Spain, in order to know the level of soil suppressiveness. Fungal parasites were identified by molecular methods. In parallel, pot tests characterized the level of soil suppressiveness and the fungal species growing from the eggs. In addition, the egg parasitic ability of ten fungal isolates per site was also assessed. The genetic profiles of fungal and bacterial populations from M10.23 and M10.55 soils were obtained by Denaturing Gradient Gel Electrophoresis (DGGE, and compared with a non-suppressive soil (M10.33. In M10.23, Meloidogyne population in soil decreased progressively throughout the rotation zucchini, tomato, and radish or spinach. The percentage of egg parasitism was 54.7% in zucchini crop, the only one in which eggs were detected. Pochonia chlamydosporia was the only fungal species isolated. In M10.55, nematode densities peaked at the end of the spring-summer crops (tomato, zucchini, and cucumber, but disease severity was lower than expected (0.2 to 6.3. The percentage of fungal egg parasitism ranged from 3 to 84.5% in these crops. The results in pot tests confirmed the suppressiveness of the M10.23 and M10.55 soils against Meloidogyne. The number of eggs per plant and the reproduction factor of the population were reduced (P < 0.05 in both non-sterilized soils compared to the sterilized ones after one nematode generation. Pochonia chlamydosporia was the only fungus isolated from Meloidogyne eggs. In in vitro tests, P. chlamydosporia isolates were able to parasitize Meloidogyne eggs from 50 to 97% irrespective of the site. DGGE fingerprints revealed a high diversity in the microbial populations analyzed. Furthermore, both bacterial and fungal genetic patterns differentiated
Gunasekera, T S; Holland, R J; Gillings, M R; Briscoe, D A; Neethling, D C; Williams, K L; Nevalainen, K M
Efficient selection of fungi for biological control of nematodes requires a series of screening assays. Assessment of genetic diversity in the candidate species maximizes the variety of the isolates tested and permits the assignment of a particular genotype with high nematophagous potential using a rapid novel assay. Molecular analyses also facilitate separation between isolates, allowing the identification of proprietary strains and trace biocontrol strains in the environment. The resistance of propagules to UV radiation is an important factor in the survival of a biocontrol agent. We have analyzed 15 strains of the nematophagous fungus Paecilomyces lilacinus using these principles. Arbitrarily primed DNA and allozyme assays were applied to place the isolates into genetic clusters, and demonstrated that some genetically related P. lilacinus strains exhibit widespread geographic distributions. When exposed to UV radiation, some weakly nematophagous strains were generally more susceptible than effective isolates. A microtitre tray-based assay used to screen the pathogenic activity of each isolate to Meloidogyne javanica egg masses revealed that the nematophagous ability varied between 37%-100%. However, there was no clear relationship between nematophagous ability and genetic clusters. Molecular characterizations revealed sufficient diversity to allow tracking of strains released into the environment.
Dimkpa, Stanley O N; Lahari, Zobaida; Shrestha, Roshi; Douglas, Alex; Gheysen, Godelieve; Price, Adam H
The root-knot nematode Meloidogyne graminicola is one of the most serious nematode pests worldwide and represents a major constraint on rice production. While variation in the susceptibility of Asian rice (Oryza sativa) exists, so far no strong and reliable resistance has been reported. Quantitative trait loci for partial resistance have been reported but no underlying genes have been tagged or cloned. Here, 332 accessions of the Rice Diversity Panel 1 were assessed for gall formation, revealing large variation across all subpopulations of rice and higher susceptibility in temperate japonica accessions. Accessions Khao Pahk Maw and LD 24 appeared to be resistant, which was confirmed in large pot experiments where no galls were observed. Detailed observations on these two accessions revealed no nematodes inside the roots 2 days after inoculation and very few females after 17 days (5 in Khao Pahk Maw and 100 in the susceptible controls). These two cultivars appear ideal donors for breeding root-knot nematode resistance. A genome-wide association study revealed 11 quantitative trait loci, two of which are close to epistatic loci detected in the Bala x Azucena population. The discussion highlights a small number of candidate genes worth exploring further, in particular many genes with lectin domains and genes on chromosome 11 with homology to the Hordeum Mla locus. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
S. A. Abolusoro
Full Text Available Studies were conducted under field and screenhouse conditions to investigate the potentials of crude aqueous leaf extract of Hyptis suaveolens in the management of the root-knot nematode Meloidogyne incognita of three cowpea varieties (Sampea 9, 10 and 11. A Randomized Complete Block Design was used in the field while a completely randomized design was used for the screenhouse trials. Results showed that the treatment significantly (p < 0.05 improved the growth and yield of the three varieties and also reduced soil nematode population and root galls. It was also observed that all the three varieties were susceptible to the root-knot nematode infestation but Sampea 10 recorded higher yield that were significant in the pot trials. Phytochemical screening revealed the presence of saponins, alkaloids, flavonoids and steroids in the leaves of H. suaveolens. For higher yield of the evaluated cowpea varieties in a nematode endemic zone, aqueous leaf extract of H. suaveolens is being recommended for infested soil treatment.
Morris, Kelly A; Langston, David B; Davis, Richard F; Noe, James P; Dickson, Don W; Timper, Patricia
Fluensulfone is a new nematicide in the flouroalkenyl chemical group. A field experiment was conducted in 2012 and 2013 to evaluate the efficacy of various application methods of fluensulfone for control of Meloidogyne spp. in cucumber (Cucumis sativus). Treatments of fluensulfone (3.0 kg a.i./ha) were applied either as preplant incorporation (PPI) or via different drip irrigation methods: drip without pulse irrigation (Drip NP), pulse irrigation 1 hr after treatment (Drip +1P), and treatment at the same time as pulse irrigation (Drip =P). The experiment had eight replications per treatment and also included a PPI treatment of oxamyl (22.5 kg a.i./ha) and a nontreated control. Compared to the control, neither the oxamyl nor the fluensulfone PPI treatments reduced root galling by Meloidogyne spp. in cucumber. Among the drip treatments, Drip NP and Drip +1P reduced root galling compared to the control. Cucumber yield was greater in all fluensulfone treatments than in the control. In a growth-chamber experiment, the systemic activity and phytotoxicity of fluensulfone were also evaluated on tomato (Solanum lycopersicum), eggplant (Solanum melongena), cucumber, and squash (Curcurbita pepo). At the seedling stage, foliage of each crop was sprayed with fluensulfone at 3, 6, and 12 g a.i./liter, oxamyl at 4.8 g a.i./liter, or water (nontreated control). Each plant was inoculated with Meloidogyne incognita juveniles 2 d after treatment. There were six replications per treatment and the experiment was conducted twice. Foliar applications of fluensulfone reduced plant vigor and dry weight of eggplant and tomato, but not cucumber or squash; application of oxamyl had no effect on the vigor or weight of any of the crops. Typically, only the highest rate of fluensulfone was phytotoxic to eggplant and tomato. Tomato was the only crop tested in which there was a reduction in the number of nematodes or galls when fluensulfone or oxamyl was applied to the foliage compared to the
Leonetti, Paola; Zonno, Maria Chiara; Molinari, Sergio; Altomare, Claudio
Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5 days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.
Twenty-two edible ginger and turmeric cultivars were screened for resistance or tolerance to Meloidogyne incognita. Plants were raised in 66 L grow bags in greenhouses in Hawaii according to established practices for producing bacterial wilt-free ginger. Three months after planting, each grow bag ...
Huynh, Bao-Lam; Matthews, William C; Ehlers, Jeffrey D; Lucas, Mitchell R; Santos, Jansen R P; Ndeve, Arsenio; Close, Timothy J; Roberts, Philip A
Genome resolution of a major QTL associated with the Rk locus in cowpea for resistance to root-knot nematodes has significance for plant breeding programs and R gene characterization. Cowpea (Vigna unguiculata L. Walp.) is a susceptible host of root-knot nematodes (Meloidogyne spp.) (RKN), major plant-parasitic pests in global agriculture. To date, breeding for host resistance in cowpea has relied on phenotypic selection which requires time-consuming and expensive controlled infection assays. To facilitate marker-based selection, we aimed to identify and map quantitative trait loci (QTL) conferring the resistance trait. One recombinant inbred line (RIL) and two F2:3 populations, each derived from a cross between a susceptible and a resistant parent, were genotyped with genome-wide single nucleotide polymorphism (SNP) markers. The populations were screened in the field for root-galling symptoms and/or under growth-chamber conditions for nematode reproduction levels using M. incognita and M. javanica biotypes. One major QTL was mapped consistently on linkage group VuLG11 of each population. By genotyping additional cowpea lines and near-isogenic lines derived from conventional backcrossing, we confirmed that the detected QTL co-localized with the genome region associated with the Rk locus for RKN resistance that has been used in conventional breeding for many decades. This chromosomal location defined with flanking markers will be a valuable target in marker-assisted breeding and for positional cloning of genes controlling RKN resistance.
Woo Jong Ha
Full Text Available A liquid bio-formulation containing chitinolytic bacteria, chitin and their products was assessed for its potential biological control against root-knot nematodes on cucumber. The bio-formulation was prepared by cultures of three chitinolytic bacteria, Chromobacterium sp. strain C-61, Lysobacter engymogenes and Serratia plymuthica in minimal medium supplemented with chitin. Under pot conditions, the bio-formulation showed better growth of cucumber plants, and less root galls and population density of Meloidogyne spp. than control media without the bio-formulation. In a greenhouse, 75-fold diluted bio-formulations were treated instead of water around cucumber plants through hoses for drip irrigation six times at 5-day intervals from the transplanting date. After 30 and 60 days, the treatment provided about 7% and 10% enhancement in the plant height and about 78% and 69% reduction in population density of Meloidogyne spp. in the rhizosphere, respectively. In addition, the experiments showed that the control effects occurred only in the soils contacted with the bio-formulation. Undiluted bio-formulations were drenched three times at 10-day intervals around cucumber plants severely infested with Meloidogyne spp. The treatment showed about 37% plant enhancement without dead plants compared with 37% death in the untreated control, and about 82% nematode reduction. These results suggest that the bio-formulation can be practically used to control the root-knot nematode on cucumber.
Root-knot nematodes (RKN; Meloidogyne spp.) are among the most destructive of the plant parasitic nematodes, infecting almost all cultivated plants and resulting in yield losses of billions of dollars annually. NPR1 (nonexpresser of pathogenesis related genes 1, AtNPR1) plays a positive role in the ...
Tian, Bao-Yu; Cao, Yi; Zhang, Ke-Qin
Endophytes are known to play important roles in plant's health and productivity. In this study, we investigated the root microbiome of tomato in association with infection by root knot nematodes. Our objectives were to observe the effects and response of the bacterial endophytes before nematode attacks and to reveal the functional attributes of microbes in plant health and nematode pathogenesis. Community analysis of root-associated microbiomes in healthy and nematode-infected tomatoes indicated that nematode infections were associated with variation and differentiation of the endophyte and rhizosphere bacterial populations in plant roots. The community of the resident endophytes in tomato root was significantly affected by nemato-pathogenesis. Remarkably, some bacterial groups in the nematode feeding structure, the root gall, were specifically enriched, suggesting an association with nematode pathogenesis. Function-based metagenomic analysis indicated that the enriched bacterial populations in root gall harbored abundant genes related to degradation of plant polysaccharides, carbohydrate and protein metabolism, and biological nitrogen fixation. Our data indicated that some of the previously assumed beneficial endophytes or bacterial associates with nematode might be involved in nematode infections of the tomato roots.
Full Text Available In 2012 and 2013, a two-year field study was conducted at the University of Ilorin Teaching and Research Farm, Ilorin, the Southern Guinea Savannah Zone, Nigeria, with the aim to investigate the effect of Trichoderma harzianumT22 as a bio-control agent against a root-knot nematode (Meloidogyne incognita on some soybean varieties. The experimental field, which naturally has been known for the presence of some nematodes such as Pratylenchus, Helicitylenchus, Radopholus, Meloidogyne, Rotylenchulus, Xyphinema, was divided into two blocks, each block consisting of three plots with alleys between blocks and plots measuring 5 m and 1.5 m respectively. All treatments were replicated five times by means of a Randomized Complete Block Design. The initial soil nematode population was increased by chopping six kilograms of Meloidogyne incognita galled roots of Celosia agentea from a pure culture into all the plots. One block was treated with bio-control agent Trichoderma harzianumT22 while the second block served as a control unit. The results show that in terms of plant height, the number of branches, yield and reduction of the soil nematode population and root galls, the plants on the Trichoderma treated plots performed significantly better (P=0.05 than those in the control unit did. This therefore implies that root-knot nematodes represent a major constraint in the production of soybean while Trichoderma harzianumT22 improves the yield growth and the yield of soybean as well as better controls soil nematode populations with respect to the control trials.
Martínez-Medina, Ainhoa; Fernandez, Ivan; Lok, Gerrit B; Pozo, María J; Pieterse, Corné M J; Van Wees, Saskia C M
Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the hormone signalling network in the host to induce resistance to nematodes. We investigated the role and the timing of the jasmonic acid (JA)- and salicylic acid (SA)-regulated defensive pathways in Trichoderma-induced resistance to the root knot nematode Meloidogyne incognita. A split-root system of tomato (Solanum lycopersicum) was used to study local and systemic induced defences by analysing nematode performance, defence gene expression, responsiveness to exogenous hormone application, and dependence on SA and JA signalling of Trichoderma-induced resistance. Root colonization by Trichoderma impeded nematode performance both locally and systemically at multiple stages of the parasitism, that is, invasion, galling and reproduction. First, Trichoderma primed SA-regulated defences, which limited nematode root invasion. Then, Trichoderma enhanced JA-regulated defences, thereby antagonizing the deregulation of JA-dependent immunity by the nematodes, which compromised galling and fecundity. Our results show that Trichoderma primes SA- and JA-dependent defences in roots, and that the priming of responsiveness to these hormones upon nematode attack is plastic and adaptive to the parasitism stage. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.
Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S.; Lozano-Torres, Jose L.; Grundler, Florian M.W.; Siddique, Shahid
When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in
Lee, Sang Il; Lee, Keon Jin; Chun, Ho Hyun; Ha, Sanghyun; Gwak, Hyun Jung; Kim, Ho Myeong; Lee, Jong-Hee; Choi, Hak-Jong; Kim, Hyeong Hwan; Shin, Teak Soo; Park, Hae Woong; Kim, Jin-Cheol
Oxalic acid has potent nematicidal activity against the root-knot nematode Meloidogyne incognita. In this study, fermentation parameters for oxalic acid production in submerged culture of Aspergillus niger F22 at 23, 25, and 30 °C were optimized in 5-L jar fermenters. The viscosity of the culture broth increased with increasing temperature. There was a negative correlation between oxalic acid production and the apparent viscosity; high volumetric productivity of oxalic acid was obtained at low apparent viscosity (less than 1000 cP), with a productivity of more than 100 mg/L h. When the apparent viscosity was over 2500 cP, the volumetric productivity decreased below 50 mg/L h. In addition, the volumetric mass transfer coefficient, K L a, positively correlated with volumetric productivity. When the K L a value increased from 0.0 to 0.017 /s, the volumetric productivity proportionally increased up to 176 mg/L h. When the temperature decreased, K L a increased due to the decrease in viscosity, leading to increased volumetric productivity. The highest productivity of 7453.3 mg/L was obtained at the lowest temperature, i.e., 23 °C. The nematicidal activity of culture filtrate was proportional to the content of oxalic acid. Based on a constant impeller tip speed, oxalic acid production was successfully scaled up to a 500-L pilot vessel, producing a final concentration comparable to that in the 5-L jar.
Jiang, Chun-Hao; Xie, Ping; Li, Ke; Xie, Yue-Sheng; Chen, Liu-Jun; Wang, Jin-Suo; Xu, Quan; Guo, Jian-Hua
Biofertilizer Ning shield was composed of different strains of plant growth promotion bacteria. In this study, the plant growth promotion and root-knot nematode disease control potential on Trichosanthes kirilowii in the field were evaluated. The application of Ning shield significantly reduced the diseases severity caused by Meloidogyne incognita, the biocontrol efficacy could reached up to 51.08%. Ning shield could also promote the growth of T. kirilowii in the field by increasing seedling emergence, height and the root weight. The results showed that the Ning shield could enhance the production yield up to 36.26%. Ning shield could also promote the plant growth by increasing the contents of available nitrogen, phosphorus, potassium and organic matter, and increasing the contents of leaf chlorophyll and carotenoid pigment. Moreover, Ning shield could efficiently enhance the medicinal compositions of Trichosanthes, referring to the polysaccharides and trichosanthin. Therefore, Ning shield is a promising biofertilizer, which can offer beneficial effects to T. kirilowii growers, including the plant growth promotion, the biological control of root-knot disease and enhancement of the yield and the medicinal quality. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.
Coupling of MIC-3 overexpression with the chromosome 11 and 14 root-knot nematode (RKN) (Meloidogyne incognita) resistance QTLs provides insights into the regulation of the RKN resistance response in Upland cotton...
High levels of resistance to root-knot nematode (RKN) (Meloidogyne incognita) in Upland cotton (Gossypium hirsutum) is mediated by two major quantitative trait loci (QTL) located on chromosomes 11 and 14. We had previously determined that MIC-3 expression played a direct role in suppressing RKN egg...
Nong, Guang; Chow, Virginia; Schmidt, Liesbeth M; Dickson, Don W; Preston, James F
Pasteuria species are endospore-forming obligate bacterial parasites of soil-inhabiting nematodes and water-inhabiting cladocerans, e.g. water fleas, and are closely related to Bacillus spp. by 16S rRNA gene sequence. As naturally occurring bacteria, biotypes of Pasteuria penetrans are attractive candidates for the biocontrol of various Meloidogyne spp. (root-knot nematodes). Failure to culture these bacteria outside their hosts has prevented isolation of genomic DNA in quantities sufficient for identification of genes associated with host recognition and virulence. We have applied multiple-strand displacement amplification (MDA) to generate DNA for comparative genomics of biotypes exhibiting different host preferences. Using the genome of Bacillus subtilis as a paradigm, MDA allowed quantitative detection and sequencing of 12 marker genes from 2000 cells. Meloidogyne spp. infected with P. penetrans P20 or B4 contained single nucleotide polymorphisms (SNPs) in the spoIIAB gene that did not change the amino acid sequence, or that substituted amino acids with similar chemical properties. Individual nematodes infected with P. penetrans P20 or B4 contained SNPs in the spoIIAB gene sequenced in MDA-generated products. Detection of SNPs in the spoIIAB gene in a nematode indicates infection by more than one genotype, supporting the need to sequence genomes of Pasteuria spp. derived from single spore isolates.
Terefe, Metasebia; Tefera, Tadele; Sakhuja, P K
Bacillus firmus, commercial WP formulation (BioNem) was evaluated against the root-knot nematode Meloidogyne incognita in a laboratory, greenhouse and under field conditions on tomato plants. In the laboratory tests, an aqueous suspension of BioNem at 0.5%, 1%, 1.5% and 2% concentration reduced egg hatching from 98% to 100%, 24-days after treatment. Treatment of second-stage juveniles with 2.5% and 3% concentration of BioNem, caused 100% inhibition of mobility, 24 h after treatment. In the green house trials, BioNem applied at 8 g/pot (1200 cc soil) planted with a tomato seedlings reduced gall formation by 91%, final nematode populations by 76% and the number of eggs by 45%. Consequently, plant height and biomass was increased by 71% and 50%, respectively, compared to the untreated control, 50-days after treatment application. Application of BioNem at 16 g/pot was phytotoxic to plants. In the field trails, BioNem applied at 200 and 400 kg ha(-1) was effective in reducing the number of galls (75-84%), and increased shoot height (29-31%) and weight (20-24%) over the untreated control, 45-days after treatment. Our results indicate that B. firmus is a promising microorganism for the biological control of M. incognita in tomato pots.
Full Text Available Abstract Background The locus Rk confers resistance against several species of root-knot nematodes (Meloidogyne spp., RKN in cowpea (Vigna unguiculata. Based on histological and reactive oxygen species (ROS profiles, Rk confers a delayed but strong resistance mechanism without a hypersensitive reaction-mediated cell death process, which allows nematode development but blocks reproduction. Results Responses to M. incognita infection in roots of resistant genotype CB46 and a susceptible near-isogenic line (null-Rk were investigated using a soybean Affymetrix GeneChip expression array at 3 and 9 days post-inoculation (dpi. At 9 dpi 552 genes were differentially expressed in incompatible interactions (infected resistant tissue compared with non-infected resistant tissue and 1,060 genes were differentially expressed in compatible interactions (infected susceptible tissue compared with non-infected susceptible tissue. At 3 dpi the differentially expressed genes were 746 for the incompatible and 623 for the compatible interactions. When expression between infected resistant and susceptible genotypes was compared, 638 and 197 genes were differentially expressed at 9 and 3 dpi, respectively. Conclusions In comparing the differentially expressed genes in response to nematode infection, a greater number and proportion of genes were down-regulated in the resistant than in the susceptible genotype, whereas more genes were up-regulated in the susceptible than in the resistant genotype. Gene ontology based functional categorization revealed that the typical defense response was partially suppressed in resistant roots, even at 9 dpi, allowing nematode juvenile development. Differences in ROS concentrations, induction of toxins and other defense related genes seem to play a role in this unique resistance mechanism.
Hari C. Meher
Full Text Available Salicylic acid-(SA is a plant defense stimulator. Exogenous application of SA might influence the status of glutathione-(GSH. GSH activates and SA alters the expression of defense genes to modulate plant resistance against pathogens. The fate of GSH in a crop following SA treatment is largely unknown. The SA-induced profiles of free reduced-, free oxidized-(GSSG and protein bound-(PSSG glutathione in tomato crop following foliar treatment of transplant at 5.0-10.0 μg mL–1 were measured by liquid chromatography. Resistance to root-knot nematode, Meloidogyne incognita damaging tomato and crop performance were also evaluated. SA treatment at 5.0-10.0 μg mL–1 to tomato transplants increased GSH, GSSG and PSSG in plant leaf and root, more so in leaf, during crop growth and development. As the fruits ripened, GSH and PSSG increased and GSSG declined. SA reduced the root infection by M. incognita, nematode reproduction and thus, improved the resistance of tomato var. Pusa Ruby, but reduced crop growth and redox status. SA at 5.0 μg mL–1 improved yield and fruit quality. The study firstly linked SA with activation of glutathione metabolism and provided an additional dimension to the mechanism of induced resistance against obligate nematode pathogen. SA increased glutathione status in tomato crop, imparted resistance against M. incognita, augmented crop yield and functional food quality. SA can be applied at 5.0 μg mL–1 for metabolic engineering of tomato at transplanting to combine host-plant resistance and health benefits in formulating a strategic nematode management decision.
Prof. Adipala Ekwamu
Tomato production in Ghana is threatened by plant parasitic nematodes, especially the root knot ... to be highly resistant to Meloidogyne spp. and also recorded the lowest reproductive factors of 0.71 and 0.53, respectively. ..... VII International.
Full Text Available Taxonomically restricted genes (TRGs, i.e., genes that are restricted to a limited subset of phylogenetically related organisms, may be important in adaptation. In parasitic organisms, TRG-encoded proteins are possible determinants of the specificity of host-parasite interactions. In the root-knot nematode (RKN Meloidogyne incognita, the map-1 gene family encodes expansin-like proteins that are secreted into plant tissues during parasitism, thought to act as effectors to promote successful root infection. MAP-1 proteins exhibit a modular architecture, with variable number and arrangement of 58 and 13-aa domains in their central part. Here, we address the evolutionary origins of this gene family using a combination of bioinformatics and molecular biology approaches. Map-1 genes were solely identified in one single member of the phylum Nematoda, i.e., the genus Meloidogyne, and not detected in any other nematode, thus indicating that the map-1 gene family is indeed a TRG family. A phylogenetic analysis of the distribution of map-1 genes in RKNs further showed that these genes are specifically present in species that reproduce by mitotic parthenogenesis, with the exception of M. floridensis, and could not be detected in RKNs reproducing by either meiotic parthenogenesis or amphimixis. These results highlight the divergence between mitotic and meiotic RKN species as a critical transition in the evolutionary history of these parasites. Analysis of the sequence conservation and organization of repeated domains in map-1 genes suggests that gene duplication(s together with domain loss/duplication have contributed to the evolution of the map-1 family, and that some strong selection mechanism may be acting upon these genes to maintain their functional role(s in the specificity of the plant-RKN interactions.
Kumari, N Swarna; Sivakumar, C V
The efficacy of the obligate bacterial parasite, Pasteuria penetrans against the rootknot nematode, Meloidogyne incognita infestation was assessed in brinjal. The seedling pans with sterilized soil were inoculated with nematodes and root powder of P. penetrans were applied at different dosages viz., 0 x 10(6), 0.5 x 10(6) spores and 1 x 10(6) spores/pan. Seeds of brinjal cv Co2 were sown in the pans and seedlings were allowed to grow. The seedlings were transplanted to microplots containing sterilized soil. Observations on nematode infestation and plant growth were recorded at seedling, flowering, and fruiting stages. Nematode infestation was significantly reduced by P. penetrans treatment. There was 22, 75 and 86% reduction in nematode population of soil over control at seedling, flowering and fruiting stages, respectively, at higher spore density (1 x 10(6)). Egg mass production was decreased by 63, 78 and 89% over control at 35 (seedling), 100 (flowering) and 160 (fruiting) days after sowing respectively, at 1 x 10(6) spores treated soil. The parasitizing ability of P. penetrans increased with the age of the crop. At higher spore density the percentage of parasitization was increased from 52.0 (35 days after sowing) to 90.0 (160 days after sowing) %. At these stages of the crop, the spore load per juvenile also increased at the higher dose. The P. penetrans application enhanced the plant growth. The weight of the shoot was increased by 17.6% whereas root weight by 41.0% over the control at fruiting stage. The experimental results revealed the potential use of P. penetrans as biological control agent of M. incognita. Application of P. penetrans spores in the nursery is a good strategy since the mass multiplication is quite difficult.
Ulloa, M; Wang, C; Saha, S; Hutmacher, R B; Stelly, D M; Jenkins, J N; Burke, J; Roberts, P A
Chromosome substitution (CS) lines in plants are a powerful genetic resource for analyzing the contribution of chromosome segments to phenotypic variance. In this study, a series of interspecific cotton (Gossypium spp.) CS lines were used to identify a new germplasm resource, and to validate chromosomal regions and favorable alleles associated with nematode or fungal disease resistance traits. The CS lines were developed in the G. hirsutum L. TM-1 background with chromosome or chromosome segment substitutions from G. barbadense L. Pima 3-79 or G. tomentosum. Root-knot nematode (Meloidogyne incognita) and fusarium wilt (Fusarium oxysporum f. sp. vasinfectum) (races 1 and 4) resistance alleles and quantitative trait loci (QTL) previously placed on cotton chromosomes using SSR markers in two interspecific recombinant inbred line populations were chosen for testing. Phenotypic responses of increased resistance or susceptibility in controlled inoculation and infested field assays confirmed the resistance QTLs, based on substitution with the positive or negative allele for resistance. Lines CS-B22Lo, CS-B04, and CS-B18 showed high resistance to nematode root-galling, confirming QTLs on chromosomes 4 and 22 (long arm) with resistance alleles from Pima 3-79. Line CS-B16 had less fusarium race 1-induced vascular root staining and higher percent survival than the TM-1 parent, confirming a major resistance QTL on chromosome 16. Lines CS-B(17-11) and CS-B17 had high fusarium race 4 vascular symptoms and low survival due to susceptible alleles introgressed from Pima 3-79, confirming the localization on chromosome 17 of an identified QTL with resistance alleles from TM1 and other resistant lines. Analyses validated regions on chromosomes 11, 16, and 17 harboring nematode and fusarium wilt resistance genes and demonstrated the value of CS lines as both a germplasm resource for breeding programs and as a powerful genetic analysis tool for determining QTL effects for disease
Hirunsalee, Anan; Barker, K. R.; Beute, M. K.
Single populations of Meloidogyne arenaria races 1 (MA1) and 2 (MA2) and M. hapla (MH), and mixed populations of MA1 + MA2 and MA1 + MH with four inoculum levels of eggs were tested on peanut cv. 'Florigiant' and M. incognita-resistant tobacco cv. 'McNair 373' in a greenhouse experiment. Root infection, female development, and reproduction of MA2 on peanut and MA1 on resistant tobacco were limited at 2 and 6 weeks. MA1, MH, and MA1 + MH on peanut had similar root infection (total parasitic forms per root unit) at both 2 and 6 weeks, and similar female development and reproduction potentials at 6 weeks. MA2 tended to depress root infection, female development, and reproduction of MA1 on peanut. MH had little effect on MA1 on this crop. On tobacco, MA2 population had greater incidence of root infection than did MH at 2 weeks. The two nematode species had similar development in roots at 6 weeks. All of these processes were restricted when either MA2 or MH was present together with MA1. As initial inoculum level of parasitically fit populations increased, relative infection ratio on both peanut and tobacco, and reproduction factor on peanut decreased. Populations that had high infection incidence and reproduction rates induced greater root galling than did other populations. Root galling was suppressed in the presence of antagonistic response between nematode populations. PMID:19277277
Full Text Available Root-knot nematodes (RKNs; Meloidogyne spp. induce feeding cells (giant cells; GCs inside a pseudo-organ (gall from still unknown root cells. Understanding GCs ontogeny is essential to the basic knowledge of RKN–plant interaction and to discover novel and effective control strategies. Hence, we report for the first time in a model plant, Arabidopsis, molecular, and cellular features concerning ectopic de novo organogenesis of RKNs GCs in leaves. RKNs induce GCs in leaves with irregular shape, a reticulated cytosol, and fragmented vacuoles as GCs from roots. Leaf cells around the nematode enter G2-M shown by ProCycB1;1:CycB1;1(NT-GUS expression, consistent to multinucleated GCs. In addition, GCs nuclei present irregular and varied sizes. All these characteristics mentioned, being equivalent to GCs in root-galls. RKNs complete their life cycle forming a gall/callus-like structure in the leaf vascular tissues resembling auxin-induced callus with an auxin-response maxima, indicated by high expression of DR5::GUS that is dependent on leaf auxin-transport. Notably, induction of leaves calli/GCs requires molecular components from roots crucial for lateral roots (LRs, auxin-induced callus and root-gall formation, i.e., LBD16. Hence, LBD16 is a xylem pole pericycle specific and local marker in LR primordia unexpectedly induced locally in the vascular tissue of leaves after RKN infection. LBD16 is also fundamental for feeding site formation as RKNs could not stablish in 35S::LBD16-SRDX leaves, and likely it is also a conserved molecular hub between biotic and developmental signals in Arabidopsis either in roots or leaves. Moreover, RKNs induce the ectopic development of roots from leaf and root-galls, also formed in mutants compromised in LR formation, arf7/arf19, slr, and alf4. Therefore, nematodes must target molecular signatures to induce post-embryogenic de novo organogenesis through the LBD16 callus formation pathway partially different from those
Islam, Afsana; Mercer, Chris F; Leung, Susanna; Dijkwel, Paul P; McManus, Michael T
The transcription of four members of the Kunitz proteinase inhibitor (KPI) gene family of white clover (Trifolium repens L.), designated as Tr-KPI1, Tr-KPI2, Tr-KPI4 and Tr-KPI5, was investigated at both local infection (roots) and systemic (leaf tissue) sites in white clover in response to infection with the clover root knot nematode (CRKN) Meloidogyne trifoliophila and the clover cyst nematode (CCN) Heterodera trifolii. Invasion by the CRKN resulted in a significant decrease in transcript abundance of Tr-KPI4 locally at both 4 days post-infection (dpi) and at 8 dpi, and an increase in transcription of Tr-KPI1 systemically at 8 dpi. In contrast, an increase in transcript abundance of all four Tr-KPI genes locally at 4 and 8 dpi, and an increase of Tr-KPI1, Tr-KPI2, and Tr-KPI5 at 8 dpi systemically was observed in response to infection with the CCN. Challenge of a resistant (R) genotype and a susceptible (S) genotype of white clover with the CCN revealed a significant increase in transcript abundance of all four Tr-KPI genes locally in the R genotype, while an increase in abundance of only Tr-KPI1, Tr-KPI2, and Tr-KPI5 was observed in the S genotype, and only at 4 dpi. The transcript abundance of a member of the1-AMINOCYCLOPROPANE-1-CARBOXYLATE (ACC) SYNTHASE gene family from white clover (Tr-ACS1) was significantly down-regulated locally in response to CRKN infection at 4 and 8 dpi and at 4 dpi, systemically, while abundance increased locally and systemically at 8 dpi in response to CCN challenge. Conversely, the abundance of the jasmonic acid (JA) signalling gene, CORONATINE-INSENSITIVE PROTEIN 1 from white clover (Tr-COI1) increased significantly at 8 dpi locally in response to CRKN infection, but decreased at 8 dpi in response to CCN infection. The significance of this differential regulation of transcription is discussed with respect to differences in infection strategy of the two nematode species.
Several root-knot nematode (Meloidogyne spp.) resistance genes have been discovered in different stone fruit crops. However, none of them has yet been cloned and they were only located on the chromosomes. In this study, a candidate root-knot nematode resistance gene (designated as psoRPM1) was isolated from the ...
Evaluation of entomopathogenic nematodes and the supernatants of the in vitro culture medium of their mutualistic bacteria for the control of the root-knot nematodes Meloidogyne incognita and M. arenaria.
Kepenekci, Ilker; Hazir, Selcuk; Lewis, Edwin E
The suppressive effects of various formulations of four entomopathogenic nematode (EPN) species and the supernatants of their mutualistic bacteria on the root-knot nematodes (RKNs) Meloidogyne incognita and M. arenaria in tomato roots were evaluated. The EPNs Steinernema carpocapsae, S. feltiae, S. glaseri and Heterorhabditis bacteriophora were applied as either live infective juveniles (IJs) or infected insect cadavers. Spent medium from culturing the bacterial symbionts Xenorhabdus bovienii and Photorhabdus luminescens kayaii with the cells removed was also applied without their nematode partners. The aqueous suspensions of IJs, infected cadaver applications of EPNs and especially treatments of X. bovienii supernatant suppressed the negative impact of RKNs on tomatoes. Specific responses to treatment were reduced RKN egg masses, increased plant height and increased fresh and dry weights compared with the control where only RKNs were applied. Among the treatments tested, the plant-dipping method of X. bovienii into bacterial culture fluid may be the most practical and effective method for M. incognita and M. arenaria control. © 2015 Society of Chemical Industry.
Pandit, Ramesh; Patel, Reena; Patel, Namrata; Bhatt, Vaibhav; Joshi, Chaitanya; Singh, Pawan Kumar; Kunjadia, Anju
Nematode-trapping fungi are well known for their inherent potential to trap and kill nematodes using specialized trapping devices. However, the molecular mechanisms underlying the trapping and subsequent processes are still unclear. Therefore, in this study, we examined differential genes expression in two nematode-trapping fungi after baiting with nematode extracts. In Arthrobotrys conoides, 809 transcripts associated with diverse functions such as signal transduction, morphogenesis, stress response and peroxisomal proteins, proteases, chitinases and genes involved in the host-pathogen interaction showed differential expression with fold change (>±1.5 fold) in the presence of nematode extract with FDR (p-value nematode-trapping fungi for its host. The findings illustrate the molecular mechanism of fungal parasitism in A. conoides which may be helpful in developing a potential biocontrol agent against parasitic nematodes.
Tomato is a widely grown vegetable in Pakistan. However, its production is severely constrained by root knot nematodes (RKNs). Accurate identification of RKNs is essential for an appropriate control program. The current study evaluated the prevalence, incidence and diversity of RKNs of tomato crops grown in the Khyber ...
Coupling of MIC-3 overexpression with the chromosomes 11 and 14 root-knot nematode (RKN) (Meloidogyne incognita) resistance QTLs provides insights into the regulation of the RKN resistance response in Upland cotton (Gossypium hirsutum).
Wubben, Martin J; Callahan, Franklin E; Jenkins, Johnie N; Deng, Dewayne D
Genetic analysis of MIC-3 transgene with RKN resistance QTLs provides insight into the resistance regulatory mechanism and provides a framework for testing additional hypotheses. Resistance to root-knot nematode (RKN) (Meloidogyne incognita) in Upland cotton (Gossypium hirsutum) is mediated by two major quantitative trait loci (QTL) located on chromosomes 11 and 14. The MIC-3 (Meloidogyne Induced Cotton3) protein accumulates specifically within the immature galls of RKN-resistant plants that possess these QTLs. Recently, we showed that MIC-3 overexpression in an RKN-susceptible cotton genotype suppressed RKN egg production but not RKN-induced root galling. In this study, the MIC-3 overexpression construct T-DNA in the single-copy transgenic line '14-7-1' was converted into a codominant molecular marker that allowed the marker assisted selection of F2:3 cotton lines, derived from a cross between 14-7-1 and M-240 RNR, having all possible combinations of the chromosomes 11 and 14 QTLs with and without the MIC-3 overexpression construct. Root-knot nematode reproduction (eggs g(-1) root) and severity of RKN-induced root galling were assessed in these lines. We discovered that the addition of MIC-3 overexpression suppressed RKN reproduction in lines lacking both resistance QTLs and in lines having only the chromosome 14 QTL, suggesting an additive effect of the MIC-3 construct with this QTL. In contrast, MIC-3 overexpression did not improve resistance in lines having the single chromosome 11 QTL or in lines having both resistance QTLs, suggesting an epistatic interaction between the chromosome 11 QTL and the MIC-3 construct. Overexpression of MIC-3 did not affect the severity of RKN-induced root galling regardless of QTL genotype. These data provide new insights into the relative order of action of the chromosomes 11 and 14 QTLs and their potential roles in regulating MIC-3 expression as part of the RKN resistance response.
Dec 15, 2009 ... effect of soil solarization using plastic mulch in controlling root-knot nematode infestation and yield of ... addition to their increased toxic effects in the soil over the .... thereby promoting conducive environment for the utiliza- ...
Leij, de F.A.A.M.
A thorough understanding of the interactions which occur between nematode parasites and nematode pests and the influence of biotic and abiotic factors on these interactions, is essential in the development of biological control agents for nematodes. The aim of this study was to develop a
Hudson B Ribeiro
ão indicativos de fitotoxicidade.The exocarp and external mesocarp of pequi fruit are discarded during the extraction of internal mesocarp which is the commercial part used as food. The objective of this research was to study the use of aqueous extract and of pequi ground-powder to the control of root-knot nematode (Meloidogyne javanica. From ground pequi fruit exocarp and external mesocarp were obtained the aquaeous extract and powder. Five doses of aquaeous extract (0.0; 2.5; 5; 10 or 20% were evaluated on root-knot nematode J2 (second stage juvenile hatching and mortality. The assays were carried out in entirely randomized design with 10 replications. The hatching assay was set in Petri plates with 800 nematode eggs and 10 mL of different doses of extract. During 14 days we counted the number of hatched juveniles under optical microscope. The mortality assay of root-knot nematode was evaluated putting 100 µL of each dose of extract plus 20 µL of supension containing 20 J2 in each cell Elisa plate. After 24 h was counted the number of live and dead juveniles. The pequi powder was tested in tomato plants in greenhouse in four doses (0; 7.5; 15 or 30 g/4 kg of soil in randomized blocks design with 10 replications per treatment. The pequi powder was incorporated to the soil seven days before transplanting and nematode eggs inoculation was carried out after transplanting. After 40 days we evaluated the number of galls, egg masses, eggs/root and J2 per 200 cm³ soil and the tomato shoot dry weight and height. The aquaeous extract reduced J2 hatching and increased J2 mortality. The increased application of powder doses reduced the number of galls, egg masses and eggs of root-knot nematodes per root system and the tomato shoot dry weight being a good indication of phytotoxicity.
Martínez-Medina, Ainhoa; Fernandez, Ivan; Lok, Gerrit B; Pozo, María J; Pieterse, Corné M J|info:eu-repo/dai/nl/113115113; Van Wees, Saskia C M|info:eu-repo/dai/nl/185445373
Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the
Rybarczyk-Mydlowska, K.D.; Maboreke, H.R.; Megen, van H.H.B.; Elsen, van den S.J.J.; Mooijman, P.J.W.; Smant, G.; Bakker, J.; Helder, J.
Background: Plant parasitic nematodes are unusual Metazoans as they are equipped with genes that allow for symbiont-independent degradation of plant cell walls. Among the cell wall-degrading enzymes, glycoside hydrolase family 5 (GHF5) cellulases are relatively well characterized, especially for
To Identify a new germplasm resource, and to validate chromosomal regions and favorable alleles associated with nematode and fungal disease resistance traits, a series of interspecific cotton (Gossypium spp.) chromosome substitution (CS) lines were used in this study. The CS lines were developed in ...
Anaerobic soil disinfestation (ASD) combined with soil solarization continues to be evaluated for management of plant-parasitic nematodes in vegetable and ornamental crops in Florida. ASD combines organic amendments and soil saturation to stimulate microbial activity and create anaerobic conditions...
Cui, Ruqiang; Zhang, Lei; Chen, Yuyan; Huang, Wenkun; Fan, Chengming; Wu, Qingsong; Peng, Deliang; da Silva, Washington; Sun, Xiaotang
The full cDNA of Mi-ace-3 encoding an acetylcholinesterase (AChE) in Meloidogyne incognita was cloned and characterized. Mi-ace-3 had an open reading frame of 1875 bp encoding 624 amino acid residues. Key residues essential to AChE structure and function were conserved. The deduced Mi-ACE-3 protein sequence had 72% amino acid similarity with that of Ditylenchus destructor Dd-AChE-3. Phylogenetic analyses using 41 AChEs from 24 species showed that Mi-ACE-3 formed a cluster with 4 other nematode AChEs. Our results revealed that the Mi-ace-3 cloned in this study, which is orthologous to Caenorhabditis elegans AChE, belongs to the nematode ACE-3/4 subgroup. There was a significant reduction in the number of galls in transgenic tobacco roots when Mi-ace-1, Mi-ace-2, and Mi-ace-3 were knocked down simultaneously, whereas little or no effect were observed when only one or two of these genes were knocked down. This is an indication that the functions of these three genes are redundant. Copyright © 2017. Published by Elsevier Inc.
Abdelnabby, Hazem; Wang, Yunhe; Xiao, Xueqiong; Wang, Gaofeng; Yang, Fan; Xiao, Yannong
The gradual withdraw of several broadly used nematicides from market has enhanced the need to develop sustainable and eco-friendly alternatives with nematicidal properties. Furfural is one of the promising alternatives to fill this need. Baseline information about the impact of furfural on egg hatch, penetration potential and ultrastructure of nematode is lacking. In this study, the reagent-grade (purity ≥ 99.0%) of furfural was applied against Meloidogyne incognita. In vitro tests showed gradual reduction in either the rate of egg hatch or second stage juvenile (J2) viability of M. incognita when immersed in concentrations ranging from 0 to 10.0 μl/ml furfural. The mean EC50 for J2 and egg hatch was 0.37 and 0.27 μl/ml furfural, respectively. Furfural, even at low concentrations, resulted in a considerable suppression in egg hatch. Hatch was 0.2 ml/kg soil. No adverse effect was detected on plants or free-living nematodes as a result of furfural application. Liquid furfural proved to have superior juvenile-suppressive effect whereas its vapor has such superiority against eggs. Scanning electron microscope (SEM) study showed irregular appearance of the body surface accompanied with some cuticle disfigurement of furfural-treated juveniles. These results indicated that furfural can adversely affect egg hatch, juvenile viability, penetration potential and ultrastructure of M. incognita. Furfural may therefore be of a considerable potential as an appropriate alternative for class I nematicides. Copyright © 2016 Elsevier Ltd. All rights reserved.
Carlos Eduardo Rossi
Full Text Available Pesquisaram-se as reações de 11 cultivares de rabanete a Meloidogyne javanica e sua patogenicidade a uma dessas cultivares. No estudo de reações, os tratamentos/cultivares foram 'Comprido Branco', 'Crimson Gigante', 'Ponta Branca', 'Comprido Vermelho', 'Serrano', 'Gigante Wurzburgo', 'Saxa', 'Redondo Vermelho', 'Redondo Gigante', 'Cometo' e 'Akamaru Hatsuka'. Determinaram-se os índices de galhas (IG e de massas de ovos (IMO, o número de nematóides no sistema radicular (NSR e por grama de raiz (NGR e o fator de reprodução (FR 53 dias após a inoculação artificial com 2.000 ovos do parasito. Em outro experimento, avaliaram-se os efeitos de três densidades populacionais do nematóide [0, 500 (nível populacional baixo e 10.000 (nível populacional alto ovos/planta] sobre as massas frescas e secas de túberas e de parte aérea da cultivar 'Redondo Gigante', 39 dias após a inoculação. Os resultados mostraram que todas as cultivares permitiram a reprodução de M. javanica, sendo portanto consideradas suscetíveis. Valores de IG e IMO foram maiores ou iguais a 2,5 e os de FR, maiores do que 8,0 para todas as cultivares estudadas. O parasito causou diminuição significativa nas massas frescas e secas de túberas e de partes aéreas nos dois níveis populacionais estudados comparados com o controle não inoculado. As médias dos tratamentos contendo níveis populacionais baixo e alto do nematóide também diferiram estatisticamente entre si, comprovando-se, assim, a sua ação patogênica sobre a cultivar avaliada.Experiments were conducted under greenhouse conditions to determine the reaction of eleven radish (Raphanus sativus cultivars to Meloidogyne javanica and the pathogenicity of this nematode to a previously selected cultivar. The cultivars tested were 'Comprido Branco', 'Crimson Gigante', 'Ponta Branca', 'Comprido Vermelho', 'Serrano', 'Gigante Wurzburgo', 'Saxa', 'Redondo Vermelho', 'Redondo Gigante', 'Cometo' and 'Akamaru
Saravanan, V S; Kalaiarasan, P; Madhaiyan, M; Thangaraju, M
To examine the zinc (Zn) solubilization potential and nematicidal properties of Gluconacetobacter diazotrophicus. Atomic Absorption Spectrophotometer, Differential Pulse Polarography and Gas Chromatography Coupled Mass Spectrometry were used to estimate the total Zn and Zn(2+) ions and identify the organic acids present in the culture supernatants. The effect of culture filtrate of Zn-amended G. diazotrophicus PAl5 on Meloidogyne incognita in tomato was examined under gnotobiotic conditions. Gluconacetobacter diazotrophicus PAl5 effectively solubilized the Zn compounds tested and 5-ketogluconic acid was identified as the major organic acid aiding the solubilization of zinc oxide. The presence of Zn compounds in the culture filtrates of G. diazotrophicus enhanced the mortality and reduced the root penetration of M. incognita under in vitro conditions. 5-ketogluconic acid produced by G. diazotrophicus mediated the solubilization process and the available Zn(2+) ions enhanced the nematicidal activity of G. diazotrophicus against M. incognita. Zn solubilization and enhanced nematicidal activity of Zn-amended G. diazotrophicus provides the possibility of exploiting it as a plant growth promoting bacteria.
Giovani O da Silva
Full Text Available Foi verificada a relação entre caracteres avaliados em campo e casa-de-vegetação, relativos à avaliação de genótipos de cenoura quanto à resistência ao nematóide-das-galhas (Meloidogyne spp., visando identificar quais caracteres possibilitam a diferenciação entre os genótipos e verificar a possibilidade de avaliação apenas em um ambiente ou a eliminação de caracteres que apresentem correlação alta. Avaliaram-se 38 progênies da população '0812518' e 31 progênies da população '0812519', além das cultivares Brasília e Kuronan como testemunhas tolerante e suscetível, respectivamente. Em campo naturalmente infestado por uma mistura de Meloidogyne incognita raça 1 e Meloidoigyne javanica, a seleção para resistência ao nematóide-das-galhas foi realizada com base na menor porcentagem de infecção na raiz principal dos genótipos de cenoura, rendimento de raiz e o fator de reprodução, enquanto que em casa-de-vegetação, para cada uma das mesmas espécies de nematóides e também para a mistura de ambas, foi medido o índice de galhas e índice de massa de ovos. Verificou-se que não houve possibilidade de seleção em apenas um dos ambientes testados ou a eliminação de caracteres, indicando que para a obtenção de cultivares mais produtivas e mais tolerantes é necessária a seleção combinada nos diferentes caracteres e ambientes. Para o experimento realizado em campo foi possível diferenciar os genótipos apenas para o rendimento de raiz. No experimento em casa-de-vegetação, para todos os caracteres foi possível identificar genótipos superiores. Porém, as médias das populações não foram melhores que a testemunha 'Brasília' da qual estas se originaram, confirmando a necessidade da busca por métodos mais eficientes de seleção.We verified the relation among the evaluated characters in field and greenhouse, concerning to the evaluation to root-knot nematode (Meloidogyne spp. for the carrot crop, to
Susceptibilidad de genotipos de Solanum spp. al nematodo causante del nudo radical Meloidogyne spp. (chitwood) Susceptibility of genotypes of Solanum spp. to the nematode causative of the root knot Meloidogyne spp. (chitwood)
Cristian Gelpud Chaves
Full Text Available El cultivo del lulo (Solanum quitoense L.) presenta una disminución en su productividad, debido al ataque de patógenos como el nematodo del nudo radical Meloidogyne spp., en el Departamento de Nariño (Colombia), se han reportado incidencias cercanas al 79%, y pérdidas del 50%. En la presente investigación, se colectaron 45 genotipos de (Solanum quitoense L.) en los Departamentos de Nariño y Putumayo y 4 genotipos silvestres (S. mammosum, S. hirtum, S. marginatum y S. umbellatum) buscando fuentes de resistencia al nematodo. Se inocularon 9 plantas de cada genotipo de dos meses de edad con 10000 huevos de Meloidogyne spp., dejando tres testigos por cada material. Las variables evaluadas fueron: altura de planta, severidad, incidencia, peso fresco (tallo y raíz) y especies prevalentes de Meloidogyne spp. Se hizo una clasificación de genotipos mediante escala de resistencia y regresión entre la severidad y las demás variables para establecer el efecto de Meloidogyne spp. sobre los genotipos de planta. Los resultados mostraron 100% de incidencia del nematodo en todos los genotipos, 2.04% genotipos resistentes, 34.7% moderadamente resistentes, 42.8% moderadamente susceptibles, 18.3% susceptibles, y 2.04% altamente susceptibles. El genotipo SQbr05 resistente, no se vio afectado por la severidad, al contrario SQbc04 genotipo susceptible, mostró reducciones significativas en peso fresco de tallo y raíz, (R² = 0.71 y 0.98), el genotipo silvestre (S. mammosum) es altamente susceptible, Meloidogyne incognita presentó 55.31% de presencia. El genotipo SQbr05 es promisorio para ser evaluado en campo.The green orange (Solanum quitoense L.) crop has decreased in its productivity due to the pathogens attack such as the root knot nematode Meloidogyne spp. In the Nariño Department of Colombia, pest incidences near to 79% and losses of 50% have been reported. In this study, 45 genotypes of Solanum quitoense were collected in Nariño and Putumayo
A field experiment was conducted from February to May, 2004 and 2005 planting seasons at the Vegetable Evaluation and Research Station Farm located at Anse Boileau, Seychelles to evaluate the effect of soil solarization using plastic mulch in controlling root-knot nematode infestation and yield of lettuce.
Bokhari, S.S.; Tariq, S.; Ali, S.A.
The mycorrhizosphere is the region around a mycorrhizal fungus in which nutrients released from the hyphae increases microbial population and its activities. In this study five mycorrhizospheric fluorescent Pseudomonas (MRFP) were evaluated for biocontrol potential under field condition using mungbean (Vigna radiata) as test plant. MRFP-249 significantly reduced Fusarium solani, Rhizoctonia solani and Macrophomina phaseolina. Whereas MRFP246 and MRFP-247 were also found effective against M. phaseolina. Mycorrhizospheric fluorescent Pseudomonas were also found effective against root knot nematode by reducing the galls on roots and nematode's penetration in roots. Highest fresh shoot weight and plant height was produced by MRFP-248. Plants grown in soil treated with Pseudomonas showed higher number of VAM spores around the mungbean roots than untreated control plants. The mycorrhizal symbiosis should not be considered merely as bipartite, plant-fungus interaction, but should instead include the associated microorganisms, particularly fluorescent Pseudomonas. (author)
Olmo, Rocío; Silva, Ana Cláudia; Díaz-Manzano, Fernando E; Cabrera, Javier; Fenoll, Carmen; Escobar, Carolina
Plant parasitic nematodes cause a great impact in agricultural systems. The search for effective control methods is partly based on the understanding of underlying molecular mechanisms leading to the formation of nematode feeding sites. In this respect, crosstalk of hormones such as auxins and cytokinins (IAA, CK) between the plant and the nematode seems to be crucial. Thence, the study of loss of function or overexpressing lines with altered IAA and CK functioning is entailed. Those lines frequently show developmental defects in the number, position and/or length of the lateral roots what could generate a bias in the interpretation of the nematode infection parameters. Here we present a protocol to assess differences in nematode infectivity with the lowest interference of root architecture phenotypes in the results. Thus, tailored growth conditions and normalization parameters facilitate the standardized phenotyping of nematode infection.
Resistência de porta-enxertos para pessegueiro e ameixeira aos nematóides causadores de galhas (Meloidogyne spp. Resistance of rootstock for peach tree and plum to root-knot nematodes (Meloidogyne spp.
José Carlos Fachinello
Full Text Available O trabalho foi realizado com o objetivo de comparar o comportamento de cinco diferentes porta-enxertos para frutas de caroço em frente a duas espécies de nematóides do gênero Meloidogyne (Meloidogyne javanica e Meloidogyne incognita. O cultivar GF 677 foi obtido a partir do cultivo in vitro e os demais porta-enxertos a partir de sementes. Aos dois meses, as plântulas foram repicadas e inoculadas com uma mistura de Meloidogyne javanica e M. incognita aos 30, 60 e 70 dias após o plantio em canteiros incorporando-se 0,2kg de solo altamente infestado com os nematóides ao redor de cada planta. Ao final do experimento, avaliaram-se o desenvolvimento das plantas e o grau de infecção de cada cultivar. O grau de resistência dos cultivares foi estimado a partir do índice de galhas, obtido através de uma escala de grau ou nota, a qual varia de 0 a 5, em função do número de galhas ou ootecas. Os resultados obtidos demonstraram que o cultivar Okinawa não apresentou galhas no sistema radicular e na análise de crescimento foi superior aos demais cultivares. Os cultivares R-15-2 e Aldrighi foram considerados resistentes aos fitonematóides por apresentarem pequeno número de galhas no sistema radicular. Já o cultivar GF 677 apresentou maior número de galhas no sistema radicular, chegando a 126 galhas/g de raiz.The work was carried out with the objective of comparing the response of five different stone fruit rootstocks to two nematode species (Meloidogyne javanica and Meloidogyne incognita. The cultivar GF677, which was obtained from in vitro cultivation and the others rootstocks, were obtained from seedlings. Two month old plants were transplanted and inoculated with a mixture of both nematode species at 30, 60, 70 days after planting, by incorporating 0.2kg of highly infested soil around each cultivar. The development of the roststocks were evaluated at the end of the experiment. Number of galls, ranging from 0 to 5 was used to score the
Root-knot nematode (meloidogyne spp.) is a seriously pest problem in smallholder tomato farms in Kenya. Awareness of the toxicity effects and increasing costs of chemical control of root-knot nematodes has led to demand for alternative nematode management strategies, including use of potential biological control agents. The use of Verticillium chlamydosporium and Pasteuria penetrans, as biocontrol agents (BCA's) in tomato nursery beds has been evaluated and the results presented. The biocontrol agents significantly lowered the number of nematodes in roots of tomato seedlings, four weeks after seeding. Alternative treatments: Crotalaria, Dazomet 98% (Basamid granular) and trash burning, significantly reduced the number of second stage juveniles in soil. Transplanting of seedlings, from BCA treatment, to a nematode infested field reduced the number of egg masses at the end of harvesting period but did not result in a significant increase in tomato yield
Karanja, D K
Root-knot nematode (meloidogyne spp.) is a seriously pest problem in smallholder tomato farms in Kenya. Awareness of the toxicity effects and increasing costs of chemical control of root-knot nematodes has led to demand for alternative nematode management strategies, including use of potential biological control agents. The use of Verticillium chlamydosporium and Pasteuria penetrans, as biocontrol agents (BCA's) in tomato nursery beds has been evaluated and the results presented. The biocontrol agents significantly lowered the number of nematodes in roots of tomato seedlings, four weeks after seeding. Alternative treatments: Crotalaria, Dazomet 98% (Basamid granular) and trash burning, significantly reduced the number of second stage juveniles in soil. Transplanting of seedlings, from BCA treatment, to a nematode infested field reduced the number of egg masses at the end of harvesting period but did not result in a significant increase in tomato yield.
Antinematicidal Efficacy Of Root Exudates Of Some Crotalaria Species On Meloidogyne Incognita Root-Knot Nematode Kofoid And White Chitwood Isolated From Infected Lycopersicum Esculentum L.Tomato Plant
Full Text Available The antinematicidal efficacies of exudates of four common weeds Crotalaria breviflora Crotalaria juncea Crotalaria retusa and Crotalaria spectabilis were carried out against Meloidogyne incognita. The young actively growing seedling of the common weeds were uprooted and taken to the laboratory for analyses. The root exudates of test plants were prepared by growing the young actively growing seedlings in test tubes wrapped with black carbon paper for five days under lighted florescent bulbs. Root exudates of Crotalaria breviflora Crotalaria juncea Crotalaria retusa and Crotalaria spectabilis exhibited nematicidal properties against the Meloidogyne incognita. The effects varied with concentrations of the exudates P0.05 using analysis of variance ANOVA. The effects also differed among test plants with Crotalaria retusa topping in terms of reduction in nematode population. This was followed by C.breviflora C.juncea and C.spectabilis respectively. The results thus confirmed that all the test plants are potentially viable trap weeds and can be used for the control of Meloidogyne incognita and should be employed as such.
Full Text Available A pot experiment was conducted during winter season of 2009–2010 in the department of Botany, AMU, Aligarh, India, to determine the nematicidal potential of organic matter, neem cake at third level of dose, and bioagent, Glomus fasciculatum in terms of various growth parameters of tomato, when inoculated individually as well as concomitantly with respect to root-knot development. Neem cake and G. fasciculatum showed potential for sustainable management while providing nutrient sources for proper plant growth. Disease intensity of root-knot nematode decreased while increasing the doses of neem cake along with the G. fasciculatum. Chlorophyll contents have been found to be increased in single and combined application as well. There is a progressive increase in growth parameters raised in soil amended with 10, 20, and 30 g neem cake/kg soil and inoculated with G. fasciculatum. Significant improvement in the plant growth was observed when G. fasciculatum and neem cake were inoculated simultaneously. Neem cake plus G. fasciculatum reduced the nematodes’ multiplication and root-galling, and increased the plant growth of tomato as compared to unamended and Meloidogyne incognita-inoculated plants. Mycorrhyzation and agronomic parameters were increased due to application of G. fasciculatum alone, but enhanced further when inoculated with neem cake.
Sep 30, 2013 ... ELISA detected Bt protein in soil and roots of Bt cotton but not in HART 89M ... as the use of organic amendments and nematicides with other .... isogenic counterpart to test the effect of the Bt gene ..... Bendezu and Starr (2003) identified two types of RKN ... soil texture, temperature, moisture, aeration and.
REAÇÃO DE GENÓTIPOS DE MILHO (Zea mays L. AOS NEMATÓIDES DE GALHAS (Meloidogyne javanica e M. incognita REACTION OF CORN GENOTYPES (Zea mays L. TO ROOT-KNOT NEMATODES (Melodoigyne javanica and M. incognita
Hércules Diniz Campos
="justify">Two experiments were carried out under greenhouse conditions with the objective of evaluating the reaction of eight corn genotypes to the root-knot nematodes Meloidogyne javanica and M. incognita. Cultivars HATÃ-1001, HATÃ-1045, DINA-657 and FT-5140 presented smaller reproduction factors (RF for M. javanica. Therefore, the use of these cultivars may be indicated in the crop rotation program with soybean. All cultivars were suitable hosts for M. incognita, presenting RF higher than 3.98.
KEY-WORDS: Resistance; root-knot; nematodes; corn.
Bert, W.; Karssen, G.; Helder, J.
Many plant-parasitic nematodes including members of the genera Meloidogyne (root-knot nematodes), Heterodera and Globodera (cyst nematodes) and Pratylenchus (lesion nematodes) are studied as they cause major damage to crops such as potato, tomato, soybean and sugar beet. Both for fundamental reasons
Waseem M. ABBASI
Full Text Available Root-knot nematode, Meloidogyne javanica (Treub Chitwood is a soil-borne plant pathogen of roots. Nematode infection results in altered plant growth and physicochemical processes due to gall formation. Many plants contain unique biochemicals that have biocidal properties and offer a potential novel approach to suppress the nematode populations in soil and improve growth of crop plants. In the present study effect of some indigenous halophytic plant species (Tamarix indica Willd, Suaeda fruticosa Forssk and Salsola imbricata (Schultz Dandy were tested against M. javanica. Tested halophytes significantly (P<0.001 reduced egg hatching and caused mortality of second stage juveniles (J2 in vitro. These halophytes when incorporated in soil (0.3, 0.5 and 1% w/w markedly increased growth of eggplant (Solanum melongena L. cv. Black beauty and okra (Abelmoschus esculentus [L.] Moench. cv. Arka anamika and provided control of root-knot infection at higher doses (0.5 and 1%. Amended eggplants and okra showed significant (P<0.001 increase in chlorophylls and decrease in chlorophyll a/b ratio. Protein concentration in leaves of both the plants were increased with 1% amendment of S. fruticosa and S. imbricata. While nucleic acid concentrations were varied with different treatments.
Mujeebur Rahman KHAN
Full Text Available Studies were conducted to determine damage potential of Meloidogyne graminicola on the commonly grown rice cv. Sugandh-5 and to devise an effective management strategy. The nematicides were applied through root-dip (200 ppm solution and soil application of 2 kg ha-1 phorate 10G (25 mg a.i./pot, carbofuran 3G (83.3 mg a.i./pot and 1 L ha-1, carbosulfan 20EC (5µL/pot and chlorpyriphos 20 EC (6.25 µL/pot in both nematode infested and non-infested soil with five modes of application viz., root-dip, single soil application (15 days after transplanting, root-dip + one soil application, two soil applications, and root-dip + two soil applications (15 and 30 days. Application of nematicides did not cause any toxicity symptoms on rice plants. In nematode infested soil, terminal and spiral galls developed on the rice roots, and plants suffered 20−31% decrease in the plant growth parameters. Carbofuran and phorate through root-dip plus single soil application provided greatest suppression in galling (16−20%, egg mass production (18−22% and soil population (27.5−58.2% of M. graminicola, and subsequently increased all the plant growth variables by 9−19%. Root-dip + two soil applications increased plant growth and suppressed nematodes, but was equal to root dip + one soil application. Root-dip treatment alone with carbosulfan also significantly suppressed root galling (10−12% and improved the dry weight of roots and shoots (7−10%.
IDENTIFICACIÓN DE GENES CANDIDATOS DE PATOGENICIDAD EN LA INTERACCIÓN DE LA CEPA CENICAFE 9501 CON EL NEMÁTODO DEL NUDO RADICAL Meloidogyne spp. IDENTIFICATION OF PATHOGENIC CANDIDATES GENES IN THE INTERACTION OF THE CENICAFE 9501 STRAIN WITH THE ROOT KNOT NEMATODE Meloidogyne spp.
Nadya Lorena Cardona Bustos
Full Text Available En 1997 se registró por primera vez el aislamiento de un hongo Hyphomycete de suelos de Chinchiná (Caldas, Colombia atacando huevos y otros estadios biológicos de las especies de nematodos fitoparásitos Meloidogyne incognita y M. javanica provenientes de lotes comerciales con café. Debido a la imposibilidad de clasificarlo taxonómicamente en los géneros actuales, este aislamiento se ha denominado temporalmente como CENICAFE 9501. Dado su potencial como biocontrolador, se propuso identificar genes candidatos involucrados en el proceso de patogenicidad de huevos de Meloidogyne. Con este fin se construyeron librerías diferenciales mediante el método de hibridación sustractiva. La secuenciación de 188 clones obtenidos permitió identificar 80 unigenes, de los cuales el mayor porcentaje correspondió a secuencias sin homología (32%, seguidas por genes candidatos a funciones de patogénesis (22%, transporte celular (17%, síntesis de proteínas (11% y en menor proporción aquellos involucrados con transcripción y metabolismo primario (18%. Dentro de aquellos genes que contienen marcos de lectura con homología a proteínas que intervienen en la patogenicidad se encuentran una peptidasa, un receptor para sitios de ubiquitinación, una deubiquinasa, una ubiquinona oxidoreductasa, proteína relacionada con la degradación de pared celular, glicosil hidrolasa e hidroxilasa de ácidos grasos, asi como una serin proteasa. Se hace necesaria la validación de las funciones putativas de estos genes candidatos con el fin de incrementar el conocimiento básico de la fisiología de este hongo con potencial biorregulador.In 1997 it was reported for the first time from soil isolation of a Hyphomycete fungus from Chinchiná ( Caldas, Colombia , attacking eggs and other biological stages of the plant parasite nematodes Meloidogyne incognita and M. javanica, from commercial coffee plots. Due to the impossibility to classify it taxonomically under current
Pasteuria species are bacterial parasites of nematodes and have been associated with suppression of root-knot, sting, and cyst nematode populations. Little is known about the Pasteuria sp. infecting the reniform nematode. While sampling a cotton field study near Cochran, GA, we found Pasteuria spo...
Imbriani, I.; Mankau, R.
The life history and feeding habits of Lasioseius scapulatus, an ascid predator and potential biocontrol agent of nematodes, was examined. Reproduction was asexual, and the life cycle was 8-10 days at room temperature. Life history consisted of the egg, protonymph, deutonymph, and adult. Both nymphal stages and the adult captured and consumed nematodes. Two fungal genera and eight genera of nematodes were suitable food sources. Second-stage root-knot nematode juveniles were eaten, but eggs an...
Mauricio Batista Fialho
Full Text Available Previous studies have demonstrated that volatile organic compounds (VOCs, produced by the yeast Saccharomyces cerevisiae, were able to inhibit the development of phytopathogenic fungi. In this context, the nematicidal potential of the synthetic mixture of VOCs, constituted of alcohols and esters, was evaluated for the control of the root-knot nematode Meloidogyne javanica, which causes losses to crops of high economic value. The fumigation of substrate containing second-stage juveniles with VOCs exhibited nematicidal effect higher than 30% for the lowest concentration tested (33.3 µL g-1 substrate, whereas at 66.6 and 133.3 µL g-1 substrate, the nematode mortality was 100%. The present results stimulate other studies on VOCs for nematode management.
Kokalis-Burelle, Nancy; Rosskopf, Erin N; Albano, Joseph P; Holzinger, John
Cut flower producers currently have limited options for nematode control. Four field trials were conducted in 2006 and 2007 to evaluate Midas® (iodomethane:chloropicrin 50:50) for control of root-knot nematodes (Meloidogyne arenaria) on Celosia argentea var. cristata in a commercial floriculture production field in southeastern Florida. Midas (224 kg/ha) was compared to methyl bromide:chloropicrin (98:2, 224 kg/ha), and an untreated control. Treatments were evaluated for effects on Meloidogyne arenaria J2 and free-living nematodes in soil through each season, and roots at the end of each season. Plant growth and root disease were also assessed. Population levels of nematodes isolated from soil were highly variable in all trials early in the season, and generally rebounded by harvest, sometimes to higher levels in fumigant treatments than in the untreated control. Although population levels of nematodes in soil were not significantly reduced during the growing season, nematodes in roots and galling at the end of the season were consistently reduced with both methyl bromide and Midas compared to the untreated control. Symptoms of phytotoxicity were observed in Midas treatments during the first year and were attributed to Fe toxicity. Fertilization was adjusted during the second year to investigate potential fumigant/fertilizer interactions. Interactions occurred at the end of the fourth trial between methyl bromide and fertilizers with respect to root-knot nematode J2 isolated from roots and galling. Fewer J2 were isolated from roots treated with a higher level of Fe (3.05%) in the form of Fe sucrate, and galling was reduced in methyl bromide treated plots treated with this fertilizer compared to Fe EDTA. Reduced galling was also seen with Midas in Fe sucrate fertilized plots compared to Fe EDTA. This research demonstrates the difficulty of reducing high root-knot nematode population levels in soil in subtropical conditions in production fields that have been
Yu, Zhen; Zhang, You-Chi; Zhang, Xiang; Wang, Yin
The feasibility of converting food waste into nematocidal biofertilizer by nematophagous fungus Paecilomyces lilacinus (P. lilacinus) was investigated. The culture conditions of P. lilacinus were optimized through response surface methodology. Results showed that fermentation time, the amount of food waste, initial pH and temperature were most important factors for P. lilacinus production. The P. lilacinus production under optimized conditions was 10(9.6 ± 0.3) conidia mL⁻¹. After fermentation, the chemical oxygen demand concentration of food waste was efficiently decreased by 81.92%. Moreover, the property evaluation of the resultant food waste as biofertilizer indicates its high quality with reference to the standard released by the Chinese Ministry of Agriculture. The protease activity and nematocidal ability of P. lilacinus cultured by food waste were 10.8% and 27% higher than those by potato dextrose agar, respectively.
May 11, 2016 ... fungus Fusarium oxysporum f.sp. conglutinans in vitro. Rajinikanth Rompalli ... Indigenous strains of Trichoderma viride (ITCC No. 6889), Pseudomonas ..... antibiotic rather than protein might be responsible for the nematicidal ...
Desaeger, J. A.; Csinos, A. S.
Combination treatments of chisel-injected fumigants (methyl bromide, 1,3-D, metam sodium, and chloropicrin) on a first crop, followed by drip-applied fumigants (metam sodium and 1,3-D ± chloropicrin) on a second crop, with and without oxamyl drip applications were evaluated for control of Meloidogyne incognita in three different tests (2002 to 2004) in Tifton, GA. First crops were eggplant or tomato, and second crops were cantaloupe, squash, or jalapeno pepper. Double-cropped vegetables suffe...
Eves-van den Akker, Sebastian; Lilley, Catherine J; Danchin, Etienne G J; Rancurel, Corinne; Cock, Peter J A; Urwin, Peter E; Jones, John T
Within the phylum Nematoda, plant-parasitism is hypothesized to have arisen independently on at least four occasions. The most economically damaging plant-parasitic nematode species, and consequently the most widely studied, are those that feed as they migrate destructively through host roots causing necrotic lesions (migratory endoparasites) and those that modify host root tissue to create a nutrient sink from which they feed (sedentary endoparasites). The false root-knot nematode Nacobbus aberrans is the only known species to have both migratory endoparasitic and sedentary endoparasitic stages within its life cycle. Moreover, its sedentary stage appears to have characteristics of both the root-knot and the cyst nematodes. We present the first large-scale genetic resource of any false-root knot nematode species. We use RNAseq to describe relative abundance changes in all expressed genes across the life cycle to provide interesting insights into the biology of this nematode as it transitions between modes of parasitism. A multigene phylogenetic analysis of N. aberrans with respect to plant-parasitic nematodes of all groups confirms its proximity to both cyst and root-knot nematodes. We present a transcriptome-wide analysis of both lateral gene transfer events and the effector complement. Comparing parasitism genes of typical root-knot and cyst nematodes to those of N. aberrans has revealed interesting similarities. Importantly, genes that were believed to be either cyst nematode, or root-knot nematode, "specific" have both been identified in N. aberrans. Our results provide insights into the characteristics of a common ancestor and the evolution of sedentary endoparasitism of plants by nematodes. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
Eves-van den Akker, Sebastian; Lilley, Catherine J.; Danchin, Etienne G. J.; Rancurel, Corinne; Cock, Peter J. A.; Urwin, Peter E.; Jones, John T.
Within the phylum Nematoda, plant-parasitism is hypothesized to have arisen independently on at least four occasions. The most economically damaging plant-parasitic nematode species, and consequently the most widely studied, are those that feed as they migrate destructively through host roots causing necrotic lesions (migratory endoparasites) and those that modify host root tissue to create a nutrient sink from which they feed (sedentary endoparasites). The false root-knot nematode Nacobbus aberrans is the only known species to have both migratory endoparasitic and sedentary endoparasitic stages within its life cycle. Moreover, its sedentary stage appears to have characteristics of both the root-knot and the cyst nematodes. We present the first large-scale genetic resource of any false-root knot nematode species. We use RNAseq to describe relative abundance changes in all expressed genes across the life cycle to provide interesting insights into the biology of this nematode as it transitions between modes of parasitism. A multigene phylogenetic analysis of N. aberrans with respect to plant-parasitic nematodes of all groups confirms its proximity to both cyst and root-knot nematodes. We present a transcriptome-wide analysis of both lateral gene transfer events and the effector complement. Comparing parasitism genes of typical root-knot and cyst nematodes to those of N. aberrans has revealed interesting similarities. Importantly, genes that were believed to be either cyst nematode, or root-knot nematode, “specific” have both been identified in N. aberrans. Our results provide insights into the characteristics of a common ancestor and the evolution of sedentary endoparasitism of plants by nematodes. PMID:25123114
Abad, P.; Gouzy, J.; Aury, J.M.; Tytgat, T.O.G.; Smant, G.
Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the
Efecto de la incorporación de plantas antagónicas sobre la actividad parasítica del nematodo del nudo de la raíz Meloidogyne hapla en un cultivo de zanahoria bajo condiciones de invernadero Effect of the incorporation of antagonistic plants on the parasitic activity of the root-knot nematode Meloidogyne hapla in a greenhouse carrot crop
Alvarez César G.
intensity of root-knotting of carrot. No significant differences were detected in the biological yield of carrot plants, but commercial average production obtained from plots.treated with R. graveolens and T. officinale were the highest (3070 g.m·2 and 2270 g.m·2 and significantly different from the control plots (1090 g.m·2. Final average population densities of infective secondstage
juveniles [J2] of M. hapla were significantly lower in the plots treated with R. communis, T. officinale, B. campes tris and T. erecta (65-130 Jj100 g of soil than in the control plots (435 J2/100 g of soil. Significant differences were detected between rootknotting intensity of control plots (5.0 knots per root tip and the averages of other treaments (1.9-2.6 knots per root tip.
Suzuki, Kenshi; Ishii, Naoaki
Utilization of nematodes for a study of radiation biology was considered. Structure, generation, rearing method, and genetic nature of nematodes (Caenorhabditis elegans, Turbatri acetic, etc.) were given an outline. As the advantage of a study using nematodes as materials, shortness of one generation time, simplicity in structure, and smallness of the whole cells, specific regular movement, and heliotaxis to chemical substances and light were mentioned. Effect of x-ray on survival rate of nematodes and effect of ultraviolet on nematodes and their eggs were described. It was suggested that nematodes was useful for studies on aging and radiation biology, and a possibility existed that nematodes would be used in studies of cancer and malformation. (Serizawa, K.)
Meyer, Susan L F
Restrictions on the use of conventional nematicides have increased the need for new methods of managing plant-parasitic nematodes. Consequently, nematode-antagonistic microbes, and active compounds produced by such organisms, are being explored as potential additions to management practices. Programs in this area at the USDA Agricultural Research Service investigate applied biocontrol agents, naturally occurring beneficial soil microbes and natural compounds. Specific research topics include use of plant growth-promoting rhizobacteria and cultural practices for management of root-knot and ring nematodes, determination of management strategies that enhance activity of naturally occurring Pasteuria species (bacterial obligate parasites of nematodes), studies on interactions between biocontrol bacteria and bacterial-feeding nematodes, and screening of microbes for compounds active against plant-parasitic nematodes. Some studies involve biocontrol agents that are active against nematodes and soil-borne plant-pathogenic fungi, or combinations of beneficial bacteria and fungi, to manage a spectrum of plant diseases or to increase efficacy over a broader range of environmental conditions. Effective methods or agents identified in the research programs are investigated as additions to existing management systems for plant-parasitic nematodes.
McLeod, Anni; Ndungu, Beth; Karanja, Daniel; Karanja, Peter
This report was presented at the UK Organic Research 2002 Conference. Root-knot nematodes in tomatoes cause financial loss to Kenyan smallholders. While soil fumigation appears to be losing effectiveness two bio-control agents (bcas), Pasteuria penetrans and Verticillium chlamydosporium, appear promising. Participatory budgeting is being used to compare the bcas with chemical and other biological controls on commercial and organic smallholdings.
Brassica plants once incorporated into soil as green manures have recently been shown to have biofumigant properties and have the potential of controlling plant-parasitic nematodes. In Washington State, plant-parasitic nematodes are successfully managed with synthetic nematicides. However, some of the synthetic nematicides became unavailable recently or their supply is limited leaving growers with few choices to control plant-parasitic nematodes. The objective of this project was to evaluate the effects of Brassica green manures on their own and in combination with reduced rates of synthetic nematicides on plant-parasitic nematodes and free living nematodes. In a greenhouse experiment and field trials in three seasons, Brassica green manures in combination with half the recommended rate of 1,3-dichloropropene (1,3-D, Telone) reduced root knot nematode, Meloidogyne chitwoodi to below detection levels, and reduced lesion nematodes, Pratylenchus penetrans and stubby root nematodes, Paratrichodorus allius, to below economic thresholds. The combination treatments did not affect the beneficial free-living nematode populations and the non-pathogenic Pseudomonas. The total cost of growing and soil-incorporating Brassica crops as green manures in combination with reduced rates of 1,3-D was approximately 35% lower than the present commercial costs for application for the full rate of this fumigant. Integrating conventional management practices with novel techniques fosters sustainability of production systems and can increase economic benefit to producers while reducing chemical input.
Sayre, R. M.
Bacillus penetrans Mankau, 1975, previously described as Duboscqia penetrans Thorne 1940, is a candidate agent for biocontrol of nematodes. This review considers the life stages of this bacterium: vegetative growth phase, colony fragmentation, sporogenesis, soil phase, spore attachment, and penetration into larvae of root-knot nematodes. The morphology of the microthallus colonies and the unusual external features of the spore are discussed. Taxonomic affinities with the actinomycetes, partic...
Full Text Available Superoxide dismutase (SOD is a constitutive family of enzymes produced by all aerobic organisms. Varying amounts of SOD activity have been found at all life stages of the most diffused plant parasitic nematodes. SOD is important to aerobic metabolism and parasitism of nematodes in that it catalyzes the first step of the neutralization of the highly toxic superoxide anion (O2 •-, which is largely produced in plant-nematode incompatible reactions. SOD has also been shown to be a significant tool to diagnose root-knot, cyst-, and longidorid nematodes. A high SOD polymorphism has been revealed by Native-Page on gradient polyacrylamide gels for Meloidogyne spp. and by isoelectrofocusing for Globodera, Xiphinema and Longidorus spp. The sensitivity of such procedures has been improved by using the PhastSystem (Amersham Biosciences, Piscata, NJ, USA, an automated equipment for electrophoresis. An accurate discrimination of species of all the nematode genera tested has been achieved and an attempt was made to group populations of the Xiphinema americanum-group and to detect Globodera rostochiensis and G. pallida pathotypes.
Cotton, James A; Lilley, Catherine J; Jones, Laura M; Kikuchi, Taisei; Reid, Adam J; Thorpe, Peter; Tsai, Isheng J; Beasley, Helen; Blok, Vivian; Cock, Peter J A; Eves-van den Akker, Sebastian; Holroyd, Nancy; Hunt, Martin; Mantelin, Sophie; Naghra, Hardeep; Pain, Arnab; Palomares-Rius, Juan E; Zarowiecki, Magdalena; Berriman, Matthew; Jones, John T; Urwin, Peter E
Globodera pallida is a devastating pathogen of potato crops, making it one of the most economically important plant parasitic nematodes. It is also an important model for the biology of cyst nematodes. Cyst nematodes and root-knot nematodes are the two most important plant parasitic nematode groups and together represent a global threat to food security. We present the complete genome sequence of G. pallida, together with transcriptomic data from most of the nematode life cycle, particularly focusing on the life cycle stages involved in root invasion and establishment of the biotrophic feeding site. Despite the relatively close phylogenetic relationship with root-knot nematodes, we describe a very different gene family content between the two groups and in particular extensive differences in the repertoire of effectors, including an enormous expansion of the SPRY domain protein family in G. pallida, which includes the SPRYSEC family of effectors. This highlights the distinct biology of cyst nematodes compared to the root-knot nematodes that were, until now, the only sedentary plant parasitic nematodes for which genome information was available. We also present in-depth descriptions of the repertoires of other genes likely to be important in understanding the unique biology of cyst nematodes and of potential drug targets and other targets for their control. The data and analyses we present will be central in exploiting post-genomic approaches in the development of much-needed novel strategies for the control of G. pallida and related pathogens.
Plant volatile signatures are often used as cues by herbivores to locate their preferred hosts. Here, we report on the volatile organic compounds used by the subterranean root-knot nematode (RKN) Meloidogyne incognita for host location. We compared responses of infective second stage juveniles (J2s)...
Full Text Available The area planted to soybean in South Africa has increased by 54% since the 2009 growing season, mainly as a result of the increasing demand for protein-rich food and fodder sources. Moreover, the introduction of advanced technology, namely the availability of genetically modified herbicide tolerant soybean cultivars also contributed towards increased soybean production. The omnipresence of plant-parasitic nematodes in local agricultural soils, however, poses a threat to the sustainable expansion and production of soybean and other rotation crops. Meloidogyne incognita and M. javanica are the predominant nematode pests in local soybean production areas and those where other grain-, legume- and/or vegetable crops are grown. The lack of registered nematicides for soybean locally, crop production systems that are conducive to nematode pest build-ups as well as the limited availability of genetic host plant resistance to root-knot nematode pests, complicate their management. Research aimed at various aspects related to soybean-nematode research, namely, audits of nematode assemblages associated with the crop, identification of genetic host plant resistance in soybean germplasm to M. incognita and M. javanica, the use of molecular markers that are linked to such genetic resistance traits as well as agronomic performance of pre-released cultivars that can be valuable to producers and the industry are accentuated in this review. Evaluation of synthetically-derived as well as biological-control agents are also discussed as complementary management tactics. It is important that lessons learned through extensive research on soybean-nematode interactions in South Africa be shared with researchers and industries in other countries as they might experience or expect similar problems and/or challenges.
Geng, Ce; Nie, Xiangtao; Tang, Zhichao; Zhang, Yuyang; Lin, Jian; Sun, Ming; Peng, Donghai
Plant-parasitic nematodes (PPNs) cause serious harm to agricultural production. Bacillus firmus shows excellent control of PPNs and has been produced as a commercial nematicide. However, its nematicidal factors and mechanisms are still unknown. In this study, we showed that B. firmus strain DS-1 has high toxicity against Meloidogyne incognita and soybean cyst nematode. We sequenced the whole genome of DS-1 and identified multiple potential virulence factors. We then focused on a peptidase S8 superfamily protein called Sep1 and demonstrated that it had toxicity against the nematodes Caenorhabditis elegans and M. incognita. The Sep1 protein exhibited serine protease activity and degraded the intestinal tissues of nematodes. Thus, the Sep1 protease of B. firmus is a novel biocontrol factor with activity against a root-knot nematode. We then used C. elegans as a model to elucidate the nematicidal mechanism of Sep1, and the results showed that Sep1 could degrade multiple intestinal and cuticle-associated proteins and destroyed host physical barriers. The knowledge gained in our study will lead to a better understanding of the mechanisms of B. firmus against PPNs and will aid in the development of novel bio-agents with increased efficacy for controlling PPNs.
Full Text Available Sedentary plant parasitic nematodes such as root-knot nematodes and cyst nematodes induce giant cells or syncytia, respectively, in their host plant’s roots. These highly specialized structures serve as feeding sites from which exclusively the nematodes withdraw nutrients. While giant cells are symplastically isolated and obtain assimilates by transporter-mediated processes syncytia are massively connected to the phloem by plasmodesmata. To support the feeding sites and the nematode during their development, phloem is induced around syncytia and giant cells. In the case of syncytia the unloading phloem consists of sieve elements and companion cells and in the case of root knots it consists exclusively of sieve elements. We applied immunohistochemistry to identify the cells within the developing phloem that responded to auxin and cytokinin. Both feeding sites themselves did not respond to either hormone. We were able to show that in root knots an auxin response precedes the differentiation of these auxin responsive cells into phloem elements. This process appears to be independent of B-type Arabidopsis response regulators. Using additional markers for tissue identity we provide evidence that around giant cells protophloem is formed and proliferates dramatically. In contrast, the phloem around syncytia responded to both hormones. The presence of companion cells as well as hormone-responsive sieve elements suggests that metaphloem development occurs. The implication of auxin and cytokinin in the further development of the metaphloem is discussed.
Engler, Janice de Almeida; Rodiuc, Natalia; Smertenko, Andrei; Abad, Pierre
The cytoskeleton is an important component of the plant's defense mechanism against the attack of pathogenic organisms. Plants however, are defenseless against parasitic root-knot and cyst nematodes and respond to the invasion by the development of a special feeding site that supplies the parasite with nutrients required for the completion of its life cycle. Recent studies of nematode invasion under treatment with cytoskeletal drugs and in mutant plants where normal functions of the cytoskeleton have been affected, demonstrate the importance of the cytoskeleton in the establishment of a feeding site and successful nematode reproduction. It appears that in the case of microfilaments, nematodes hijack the intracellular machinery that regulates actin dynamics and modulate the organization and properties of the actin filament network. Intervening with this process reduces the nematode infection efficiency and inhibits its life cycle. This discovery uncovers a new pathway that can be exploited for the protection of plants against nematodes.
Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin
The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.
Neil D Warnock
Full Text Available Plant parasitic nematodes (PPNs seriously threaten global food security. Conventionally an integrated approach to PPN management has relied heavily on carbamate, organophosphate and fumigant nematicides which are now being withdrawn over environmental health and safety concerns. This progressive withdrawal has left a significant shortcoming in our ability to manage these economically important parasites, and highlights the need for novel and robust control methods. Nematodes can assimilate exogenous peptides through retrograde transport along the chemosensory amphid neurons. Peptides can accumulate within cells of the central nerve ring and can elicit physiological effects when released to interact with receptors on adjoining cells. We have profiled bioactive neuropeptides from the neuropeptide-like protein (NLP family of PPNs as novel nematicides, and have identified numerous discrete NLPs that negatively impact chemosensation, host invasion and stylet thrusting of the root knot nematode Meloidogyne incognita and the potato cyst nematode Globodera pallida. Transgenic secretion of these peptides from the rhizobacterium, Bacillus subtilis, and the terrestrial microalgae Chlamydomonas reinhardtii reduce tomato infection levels by up to 90% when compared with controls. These data pave the way for the exploitation of nematode neuropeptides as a novel class of plant protective nematicide, using novel non-food transgenic delivery systems which could be deployed on farmer-preferred cultivars.
Cotton, James A
Background: Globodera pallida is a devastating pathogen of potato crops, making it one of the most economically important plant parasitic nematodes. It is also an important model for the biology of cyst nematodes. Cyst nematodes and root-knot nematodes are the two most important plant parasitic nematode groups and together represent a global threat to food security. Results: We present the complete genome sequence of G. pallida, together with transcriptomic data from most of the nematode life cycle, particularly focusing on the life cycle stages involved in root invasion and establishment of the biotrophic feeding site. Despite the relatively close phylogenetic relationship with root-knot nematodes, we describe a very different gene family content between the two groups and in particular extensive differences in the repertoire of effectors, including an enormous expansion of the SPRY domain protein family in G. pallida, which includes the SPRYSEC family of effectors. This highlights the distinct biology of cyst nematodes compared to the root-knot nematodes that were, until now, the only sedentary plant parasitic nematodes for which genome information was available. We also present in-depth descriptions of the repertoires of other genes likely to be important in understanding the unique biology of cyst nematodes and of potential drug targets and other targets for their control. Conclusions: The data and analyses we present will be central in exploiting post-genomic approaches in the development of much-needed novel strategies for the control of G. pallida and related pathogens. 2014 Cotton et al.; licensee BioMed Central Ltd.
Jones, John T; Haegeman, Annelies; Danchin, Etienne G J; Gaur, Hari S; Helder, Johannes; Jones, Michael G K; Kikuchi, Taisei; Manzanilla-López, Rosa; Palomares-Rius, Juan E; Wesemael, Wim M L; Perry, Roland N
The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a 'top 10' list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly. © 2013 BSPP AND JOHN WILEY & SONS LTD.
The objective of this work is to develop resistance to root-knot nematodes in tomato by induction, selection and utilization of the newly created resistant strains. Seeds of two varieties of tomato Lycopersicon esculentum L., namely Amcopack and Supermarmande, were subjected to various doses of gamma rays ranging from 10 Krads to 40 Krads in an effort to gain resistance to Meloidogyne incognita Chitwood, the prevalent species of nematodes in Lebanon. The variety Supermarmande seemed not to be affected by irradiation while Amcopack gained some resistance with a corresponding increase in the dose of radiation. The data suggest that in a variety like Amcopack, irradiation may stimulate resistance while in others like Supermarmande, susceptibility is not reduced with a corresponding increase of dosage. Those alterations in reaction within varieties may be due to genetic differences which allow some varieties to acquire resistance to nematodes when exposed to certain dosages, while others to suffer seriously due to sensitivity. (author)
Greenhouse and field experiments were undertaken to determine the possibility of using soil amendments with different C:N levels or applied at different rates and times in the control of root-knot nematodes (Meloidogyne spp.)in tomato c.v Cal J.A naturally infested field was used while artificial inoculation was done in the greenhouse. Root galling was rated on a scale of 0-10, nematode population was estimated by counting second stage juveniles extracted from 200 cm 3 soil and fruit yields were recorded at the end of the season. Nematode population densities and galling indices were significantly (P< or=0.05) lower in amended soils compared to the control. Application of the amendments also resulted in significant (P< or=0.05) increase in yields. Chicken manure, compost manure, neem products and pig manure were were the most effective amendments. Fresh chicken manure had a more suppressive effect on nematode than when the manure was decomposed within or outside a nematode infested field. A general decrease in juvenile populations and galling was observed with increase of organic amendments applied
Muhammad A. Ali
Full Text Available Plant parasitic nematodes (PPNs are obligate biotrophic parasites causing serious damage and reduction in crop yields. Several economically important genera parasitize various crop plants. The root-knot, root lesion, and cyst nematodes are the three most economically damaging genera of PPNs on crops within the family Heteroderidae. It is very important to devise various management strategies against PPNs in economically important crop plants. Genetic engineering has proven a promising tool for the development of biotic and abiotic stress tolerance in crop plants. Additionally, the genetic engineering leading to transgenic plants harboring nematode resistance genes has demonstrated its significance in the field of plant nematology. Here, we have discussed the use of genetic engineering for the development of nematode resistance in plants. This review article also provides a detailed account of transgenic strategies for the resistance against PPNs. The strategies include natural resistance genes, cloning of proteinase inhibitor coding genes, anti-nematodal proteins and use of RNA interference to suppress nematode effectors. Furthermore, the manipulation of expression levels of genes induced and suppressed by nematodes has also been suggested as an innovative approach for inducing nematode resistance in plants. The information in this article will provide an array of possibilities to engineer resistance against PPNs in different crop plants.
Verbeek, R.; Banaay, C.; Sikder, M.; De Waele, D.; Vera Cruz, C.; Gheysen, G.; Höfte, M.; Kyndt, Tina
Pythium arrhenomanes DNA in rice roots expressed as picogram Pythium DNA per nanogram total DNA. Varieties Palawan (A) and IR81413-BB-75-4 (B) quantified with P. arrhenomanes specific and plant specific primers at 2, 10, 20, 45 and 60 days after transplanting in the raised bed experiment. ‘Natural infestation’ = soil taken from field B912 and ‘Natural infestation + P. arrhenomanes’ = B912 soil with additional P. arrhenomanes inoculation. Each treatment has two biological replicates (of three ...
Giblin-Davis, R M; Williams, D S; Bekal, S; Dickson, D W; Brito, J A; Becker, J O; Preston, J F
Taxonomically relevant characteristics of a fastidiously Gram-positive, obligately endoparasitic prokaryote (strain S-1) that uses the phytoparasitic sting nematode Belonolaimus longicaudatus as its host are reviewed. 16S rDNA sequence similarity (> or = 93%) confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans and corroborates morphological, morphometric and host range evidence suggesting a novel taxon. The 16S rDNA sequence of strain S-1 has greatest similarity (96%) to the 16S rDNA sequences of both Pasteuria penetrans from root-knot nematodes (Meloidogyne species) and the recently reported strain of Pasteuria isolated from the soybean cyst nematode Heterodera glycines. Because the obligately endoparasitic nature of prokaryotes in the genus Pasteuria prevents isolation of definitive type strains, strain S-1 is proposed as 'Candidatus Pasteuria usgae' sp. nov.
Habiba, A.; Noreen, R.; Ali, S. A.; Sultana, V.; Ara, J.
Endophytic and rhizospheric fluorescent Pseudomonas have widely been used as biological control agents against soilborne plant pathogens. In this study, fifteen epiphytic fluorescent Pseudomonas isolated from the surfaces of citrus (grapefruit, orange and lemon) melon and tomato fruits were characterized for their in vitro activity against root rotting fungi viz., Macrophomina phaseolina, Fusarium solani, F. oxysporum and Rhizoctonia solani and nematicidal activity against the second stage juveniles of Meloidogyne javanica. Out of fifteen Pseudomonas isolates HAB-16, HAB-1 and HAB-25 inhibited the growth of all the test fungi and showed maximum nematicidal activity against second stage juvenile of M. javanica. Based on their effective in vitro activity nine epiphytic fluorescent Pseudomonas were evaluated for their growth promoting ability and biocontrol activity in screen house on mungbean. Pseudomonas isolates (HAB-13, HAB-2, HAB-4, HAB-1, HAB-14, HAB-9, HAB-7 and HAB-25) used as soil drench greatly reduced the root rot-root knot infection and thereby enhanced plant growth, root nodulation and yield in mungbean. Besides, rhizospheric and endophytic, epiphytic fluorescent Pseudomonas associated with healthy fruits may be used as biocontrol agent against root rotting fungi, besides, using for the mangemnet of postharvest diseases. (author)
Bałazy, Stanisław; Wrzosek, Marta; Sosnowska, Danuta; Tkaczuk, Cezary; Muszewska, Anna
Laboratory assays have been carried out to artificially infect insect larvae of the birch bark-beetle (Scolytus ratzeburgi Jans.-Coleoptera, Scolytidae) and codling moth Cydia pomonella L. -Lepidoptera, Tortricidae) as well as the potato cyst nematode-Globodera rostochiensis Wollenweber, sugar beet nematode-Heterodera schachtii Schmidt and root-knot nematode-Meloidogyne hapla Chif (Nematoda, Heteroderidae), by the phialoconidia of some fungal species of the genus Hirsutella. From among four species tested on insects only H. nodulosa Petch infected about 20% of S. ratzeburgi larvae, whereas H. kirchneri (Rostrup) Minter, Brady et Hall, H. minnesotensis Chen, Liu et Chen, and H. rostrata Bałazy et Wiśniewski did not affect insect larvae. Only single eggs of the root-knot nematode were infected by H. minnesotensis in the laboratory trials, whereas its larvae remained unaffected. No infection cases of the potato cyst nematode (G. rostochiensis) and sugar beet nematode eggs were obtained. Comparisons of DNA-ITS-region sequences of the investigated strains with GenBank data showed no differences between H. minnesotensis isolates from the nematodes Heterodera glycines Ichinohe and from tarsonemid mites (authors' isolate). A fragment of ITS 2 with the sequence characteristic only for H. minnesotensis was selected. Two cluster analyses indicated close similarity of this species to H. thompsonii as sister clades, but the latter appeared more heterogenous. Insect and mite pathogenic species H. nodulosa localizes close to specialized aphid pathogen H. aphidis, whereas the phytophagous mite pathogens H. kirchneri and H. gregis form a separate sister clade. Hirsutella rostrata does not show remarkable relations to the establishment of aforementioned groups. Interrelated considerations on the morphology, biology and DNA sequencing of investigated Hirsutella species state their identification more precisely and facilitate the establishment of systematic positions.
Juan E. Palomares-Rius
Full Text Available Plant-parasitic nematodes (PPNs interact with plants in different ways, for example, through subtle feeding behavior, migrating destructively through infected tissues, or acting as virus-vectors for nepoviruses. They are all obligate biotrophic parasites as they derive their nutrients from living cells which they modify using pharyngeal gland secretions prior to food ingestion. Some of them can also shield themselves against plant defenses to sustain a relatively long lasting interaction while feeding. This paper is centered on cell types or organs that are newly induced in plants during PPN parasitism, including recent approaches to their study based on molecular biology combined with cell biology-histopathology. This issue has already been reviewed extensively for major PPNs (i.e., root-knot or cyst nematodes, but not for other genera (viz. Nacobbus aberrans, Rotylenchulus spp.. PPNs have evolved with plants and this co-evolution process has allowed the induction of new types of plant cells necessary for their parasitism. There are four basic types of feeding cells: (i non-hypertrophied nurse cells; (ii single giant cells; (iii syncytia; and (iv coenocytes. Variations in the structure of these cells within each group are also present between some genera depending on the nematode species viz. Meloidogyne or Rotylenchulus. This variability of feeding sites may be related in some way to PPN life style (migratory ectoparasites, sedentary ectoparasites, migratory ecto-endoparasites, migratory endoparasites, or sedentary endoparasites. Apart from their co-evolution with plants, the response of plant cells and roots are closely related to feeding behavior, the anatomy of the nematode (mainly stylet size, which could reach different types of cells in the plant, and the secretory fluids produced in the pharyngeal glands. These secretory fluids are injected through the stylet into perforated cells where they modify plant cytoplasm prior to food removal
Hussey, Richard S; Huang, Guozhong; Allen, Rex
Identifying parasitism genes encoding proteins secreted from a plant-parasitic nematode's esophageal gland cells and injected through its stylet into plant tissue is the key to understanding the molecular basis of nematode parasitism of plants. Parasitism genes have been cloned by directly microaspirating the cytoplasm from the esophageal gland cells of different parasitic stages of cyst or root-knot nematodes to provide mRNA to create a gland cell-specific cDNA library by long-distance reverse-transcriptase polymerase chain reaction. cDNA clones are sequenced and deduced protein sequences with a signal peptide for secretion are identified for high-throughput in situ hybridization to confirm gland-specific expression.
Humphreys-Pereira, Danny A; Elling, Axel A
Root-knot nematodes (Meloidogyne spp.) are among the most important plant pathogens. In this study, the mitochondrial (mt) genomes of the root-knot nematodes, M. chitwoodi and M. incognita were sequenced. PCR analyses suggest that both mt genomes are circular, with an estimated size of 19.7 and 18.6-19.1kb, respectively. The mt genomes each contain a large non-coding region with tandem repeats and the control region. The mt gene arrangement of M. chitwoodi and M. incognita is unlike that of other nematodes. Sequence alignments of the two Meloidogyne mt genomes showed three translocations; two in transfer RNAs and one in cox2. Compared with other nematode mt genomes, the gene arrangement of M. chitwoodi and M. incognita was most similar to Pratylenchus vulnus. Phylogenetic analyses (Maximum Likelihood and Bayesian inference) were conducted using 78 complete mt genomes of diverse nematode species. Analyses based on nucleotides and amino acids of the 12 protein-coding mt genes showed strong support for the monophyly of class Chromadorea, but only amino acid-based analyses supported the monophyly of class Enoplea. The suborder Spirurina was not monophyletic in any of the phylogenetic analyses, contradicting the Clade III model, which groups Ascaridomorpha, Spiruromorpha and Oxyuridomorpha based on the small subunit ribosomal RNA gene. Importantly, comparisons of mt gene arrangement and tree-based methods placed Meloidogyne as sister taxa of Pratylenchus, a migratory plant endoparasitic nematode, and not with the sedentary endoparasitic Heterodera. Thus, comparative analyses of mt genomes suggest that sedentary endoparasitism in Meloidogyne and Heterodera is based on convergent evolution. Copyright © 2014 Elsevier B.V. All rights reserved.
Phenylacetic acid-producing Rhizoctonia solani represses the biosynthesis of nematicidal compounds in vitro and influences biocontrol of Meloidogyne incognita in tomato by Pseudomonas fluorescens strain CHA0 and its GM derivatives.
Siddiqui, I A; Shaukat, S S
The aim of the present investigation was to determine the influence of Rhizoctonia solani and its pathogenicity factor on the production of nematicidal agent(s) by Pseudomonas fluorescens strain CHA0 and its GM derivatives in vitro and nematode biocontrol potential by bacterial inoculants in tomato. One (Rs7) of the nine R. solani isolates from infected tomato roots inhibited seedling emergence and caused root rot in tomato. Thin layer chromatography revealed that culture filtrates of two isolates (Rs3 and Rs7) produced brown spots at Rf-values closely similar to synthetic phenylacetic acid (PAA), a phytotoxic factor. Filtrates from isolate Rs7, amended with the growth medium of P. fluorescens, markedly repressed nematicidal activity and PhlA'-'LacZ reporter gene expression of the bacteria in vitro. On the contrary, isolate Rs4 enhanced nematicidal potential of a 2,4-diacetylphloroglucinol overproducing mutant, CHA0/pME3424, of P. fluorescens strain CHA0 in vitro. Therefore, R. solani isolates Rs4 and Rs7 were tested more rigorously for their potential to influence biocontrol effectiveness of the bacterial agents. Methanol extract of the culture filtrates of PAA-producing isolate Rs7 resulting from medium amended with phenylalanine enhanced fungal repression of the production of nematicidal agents by bacteria, while amendments with zinc or molybdenum eliminated such fungal repression, thereby restoring bacterial potential to cause nematode mortality in vitro. A pot experiment was carried out, 3-week-old tomato seedlings were infested with R. solani isolates Rs4 or Rs7 and/or inoculated with Meloidogyne incognita, the root-knot nematode. The infested soil was treated with aqueous cell suspensions (10(8) CFU) of P. fluorescens strain CHA0 or its GM derivatives or left untreated (as a control). Observations taken 45 days after nematode inoculation revealed that, irrespective of the bacterial treatments, galling intensity per gram of fresh tomato roots was markedly
Beom Ryong Kang
Full Text Available Root-knot nematodes (Meloidogyne spp. are parasites that attack many field crops and orchard trees, and affect both the quantity and quality of the products. A root-colonizing bacterium, Pseudomonas chlororaphis O6, possesses beneficial traits including strong nematicidal activity. To determine the molecular mechanisms involved in the nematicidal activity of P. chlororaphis O6, we constructed two mutants; one lacking hydrogen cyanide production, and a second lacking an insecticidal toxin, FitD. Root drenching with wild-type P. chlororaphis O6 cells caused juvenile mortality in vitro and in planta. Efficacy was not altered in the fitD mutant compared to the wild-type but was reduced in both bioassays for the mutant lacking hydrogen cyanide production. The reduced number of galls on tomato plants caused by the wild-type strain was comparable to that of a standard chemical nematicide. These findings suggest that hydrogen cyanide-producing root colonizers, such as P. chlororaphis O6, could be formulated as “green” nematicides that are compatible with many crops and offer agricultural sustainability.
Full Text Available Pseudomonas putida 1A00316 isolated from Antarctic soil showed nematicidal potential for biological control of Meloidogyne incognita; however, little was known about whether strain 1A00316 could produce volatile organic compounds (VOCs, and if they had potential for use in biological control against M. incognita. In this study, VOCs produced by a culture filtrate of P. putida 1A00316 were evaluated by in vitro experiments in three-compartment Petri dishes and 96-well culture plates. Our results showed that M. incognita juveniles gradually reduced their movement within 24–48 h of incubation with mortality ranging from 6.49 to 86.19%, and mostly stopped action after 72 h. Moreover, egg hatching in culture filtrates of strain 1A00316 was much reduced compared to that in sterile distilled water or culture medium. Volatiles from P. putida 1A00316 analysis carried out by solid-phase micro-extraction gas chromatography–mass spectrometry (SPME-GC/MS included dimethyl-disulfide, 1-undecene, 2-nonanone, 2-octanone, (Z-hexen-1-ol acetate, 2-undecanone, and 1-(ethenyloxy-octadecane. Of these, dimethyl-disulfide, 2-nonanone, 2-octanone, (Z-hexen-1-ol acetate, and 2-undecanone had strong nematicidal activity against M. incognita J2 larvae by direct-contact in 96-well culture plates, and only 2-undecanone acted as a fumigant. In addition, the seven VOCs inhibited egg hatching of M. incognita both by direct-contact and by fumigation. All of the seven VOCs repelled M. incognita J2 juveniles in 2% water agar Petri plates. These results show that VOCs from strain 1A00316 act on different stages in the development of M. incognita via nematicidal, fumigant, and repellent activities and have potential for development as agents with multiple modes of control of root-knot nematodes.
Rodiuc, Natalia; Vieira, Paulo; Banora, Mohamed Youssef; de Almeida Engler, Janice
Transfer cells are ubiquitous plant cells that play an important role in plant development as well as in responses to biotic and abiotic stresses. They are highly specialized and differentiated cells playing a central role in the acquisition, distribution and exchange of nutrients. Their unique structural traits are characterized by augmented ingrowths of invaginated secondary wall material, unsheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Similar morphological features can be perceived in vascular root feeding cells induced by sedentary plant-parasitic nematodes, such as root-knot and cyst nematodes, in a wide range of plant hosts. Despite their close phylogenetic relationship, these obligatory biotrophic plant pathogens engage different approaches when reprogramming root cells into giant cells or syncytia, respectively. Both nematode feeding-cells types will serve as the main source of nutrients until the end of the nematode life cycle. In both cases, these nematodes are able to remarkably maneuver and reprogram plant host cells. In this review we will discuss the structure, function and formation of these specialized multinucleate cells that act as nutrient transfer cells accumulating and synthesizing components needed for survival and successful offspring of plant-parasitic nematodes. Plant cells with transfer-like functions are also a renowned subject of interest involving still poorly understood molecular and cellular transport processes.
Full Text Available Transfer cells are ubiquitous plant cells that play an important role in plant development as well as in responses to biotic and abiotic stresses. They are highly specialized and differentiated cells playing a central role in the acquisition, distribution and exchange of nutrients. Their unique structural traits are characterized by augmented ingrowths of invaginated secondary wall material, unsheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Similar morphological features can be perceived in vascular root feeding cells induced by sedentary plant-parasitic nematodes, such as root-knot and cyst nematodes, in a wide range of plant hosts. Despite their close phylogenetic relationship, these obligatory biotrophic plant pathogens engage different approaches when reprogramming root cells into giant cells or syncytia, respectively. Both nematode feeding-cells types will serve as the main source of nutrients until the end of the nematode life cycle. In both cases, these nematodes are able to remarkably maneuver and reprogram plant host cells. In this review we will discuss the structural, functional and morphogenetic characteristics function and formation of these specialized multinucleate cells that act as nutrient transfer cells to accumulate and synthesize components needed for survival and successful offspring of plant-parasitic nematodes. Plant cells with transfer-like functions are also a renowned subject of interest involving still poorly understood molecular and cellular transport processes.
Persson, Christina; Jansson, Hans-Börje
The ability of nematode-trapping fungi to colonize the rhizosphere of crop plants has been suggested to be an important factor in biological control of root-infecting nematodes. In this study, rhizosphere colonization was evaluated for 38 isolates of nematode-trapping fungi representing 11 species. In an initial screen, Arthrobotrys dactyloides, A. superba, and Monacrosporium ellipsosporum were most frequently detected in the tomato rhizosphere. In subsequent pot experiments these fungi and the non-root colonizing M. geophyropagum were introduced to soil in a sodium alginate matrix, and further tested both for establishment in the tomato rhizosphere and suppression of root-knot nematodes. The knob-forming M. ellipsosporum showed a high capacity to colonize the rhizosphere both in the initial screen and the pot experiments, with more than twice as many fungal propagules in the rhizosphere as in the root-free soil. However, neither this fungus nor the other nematode-trapping fungi tested reduced nematode damage to tomato plants. PMID:19270886
Luc, John E; Pang, Wenjing; Crow, William T; Giblin-Davis, Robin M
The effect of nematode population density at the time of application and formulations of in vitro-produced Pasteuria spp. endospores on the final population density of Belonolaimus longicaudatus was studied in an 84-d-long pot bioassay. The experiment utilized a factorial design consisting of 30 or 300 B. longicaudatus /100 cm(3) of sandy soil and three formulations of in vitro-produced Pasteuria spp. endospores (nontreated, granular, or liquid). No differences were observed in percent endospore attachment between nematode inoculum levels during either trial. Granular and liquid formulations of in vitro-produced endospores suppressed nematode population densities by 22% and 59% in the first trial and 20% and 63% in the second, respectively compared with the nontreated control. The liquid formulation increased percent endospore attachment by 147% and 158%, respectively, compared with the granular formulation. The greatest root retention by the host plant was observed at the lower B. longicaudatus inoculation level following application of the liquid formulation. While both the granular and liquid formulations reduced B. longicaudatus population densities in the soil, the liquid spore suspension was most effective.
Said K. Ibrahim
Full Text Available Ibrahim Said K., Ibrahim Azar, Christian Naser, Badran Akikki and Ludmilla Ibrahim. 2016. Plant-parasitic nematodes on stone fruits and citrus in Lebanon. Lebanese Science Journal, 17(1: 9-24. This study aimed to determine the occurrence, distribution of plant parasitic nematodes on stone fruits in Lebanon and to determine the effect of plant extracts on the mortality of several nematode species. A total of 308 soil samples were collected from five different crops. Almost all surveyed areas showed infection with nematodes. The soil infestation rate with nematodes in collected soil samples from all 10 surveyed crops ranged from 66.6 to 100%. Eighteen out of 308 soil samples were free of nematodes (5.8%. All the collected soil samples from nectarine and plum orchards were infested with nematodes (100%, followed by citrus (97.6%, apple (88.7%, pear and quince (85.7%, and cherry (81.4%. The lowest infection (66.6% was detected on almond and apricot. The level of infestation varied from one area to another and ranged between 0.1 and 28 nematodes per 1 g of soil, with the highest number obtained on cherry. Several genera were identified based on morphological characters including: root-knot nematodes (Meloidogyne spp., Tylenchulus, Xiphinema, Rotylenchus, Pratylenchus, and Longidorus. Tylenchulus and Radopholus spp. were the most common on citrus trees, whereas Pratylechus and Meloidogyne spp. were detected almost in all the samples collected from all the crops. Six chopped aromatic plants were tested in pot experiments to control nematodes population densities. The results revealed that carbofuran (nematicide was the most effective (88.48% in comparison to the plant materials. Allium sativum gave the highest control (76.52% followed by Tageta patula (72.0%, Cucurbita maxima (71.84% and Inula viscosa (63.96%. Origanum syriacum (55.04% and Thymus (53.72% were less effective in comparison to the rest of tested plant materials.
Sindhu, Anoop S; Maier, Tom R; Mitchum, Melissa G; Hussey, Richard S; Davis, Eric L; Baum, Thomas J
Cyst nematodes are highly evolved sedentary plant endoparasites that use parasitism proteins injected through the stylet into host tissues to successfully parasitize plants. These secretory proteins likely are essential for parasitism as they are involved in a variety of parasitic events leading to the establishment of specialized feeding cells required by the nematode to obtain nourishment. With the advent of RNA interference (RNAi) technology and the demonstration of host-induced gene silencing in parasites, a new strategy to control pests and pathogens has become available, particularly in root-knot nematodes. Plant host-induced silencing of cyst nematode genes so far has had only limited success but similarly should disrupt the parasitic cycle and render the host plant resistant. Additional in planta RNAi data for cyst nematodes are being provided by targeting four parasitism genes through host-induced RNAi gene silencing in transgenic Arabidopsis thaliana, which is a host for the sugar beet cyst nematode Heterodera schachtii. Here it is reported that mRNA abundances of targeted nematode genes were specifically reduced in nematodes feeding on plants expressing corresponding RNAi constructs. Furthermore, this host-induced RNAi of all four nematode parasitism genes led to a reduction in the number of mature nematode females. Although no complete resistance was observed, the reduction of developing females ranged from 23% to 64% in different RNAi lines. These observations demonstrate the relevance of the targeted parasitism genes during the nematode life cycle and, potentially more importantly, suggest that a viable level of resistance in crop plants may be accomplished in the future using this technology against cyst nematodes.
Sung Min Hwang
Full Text Available Root-knot nematodes represent a significant problem in cucumber, causing reduction in yield and quality. To develop screening methods for resistance of cucumber to root-knot nematode Meloidogyne incognita, development of root-knot nematode of four cucumber cultivars (‘Dragonsamchuk’, ‘Asiastrike’, ‘Nebakja’ and ‘Hanelbakdadaki’ according to several conditions such as inoculum concentration, plant growth stage and transplanting period was investigated by the number of galls and egg masses produced in each seedling 45 days after inoculation. There was no difference in galls and egg masses according to the tested condition except for inoculum concentration. Reproduction of the nematode on all the tested cultivars according to inoculum concentration increased in a dose-dependent manner. On the basis of the result, the optimum conditions for root-knot development on the cultivars is to transplant period of 1 week, inoculum concentration of 5,000 eggs/plant and plant growth stage of 3-week-old in a greenhouse (25 ± 5°C. In addition, under optimum conditions, resistance of 45 commercial cucumber cultivars was evaluated. One rootstock cultivar, Union was moderately resistant to the root-knot nematode. However, no significant difference was in the resistance of the others cultivar. According to the result, we suggest an efficient screening method for new resistant cucumber to the root-knot nematode, M. incognita.
Ibrahim, S.K.; Azar, I.; Naser, CH.; Akikki, B; Ibrahim, L.
This study aimed to determine the occurrence, distribution of plant parasitic nematodes on stone fruits in Lebanon and to determine the effect of plant extracts on the mortality of several nematode species. A total of 308 soil samples were collected from five different crops. Almost all surveyed areas showed infection with nematodes.The soil infestation rate with nematodes in collected soil samples from all 10 surveyed crops ranged from 66.6 to 100%. Eighteen out of 308 soil samples were free of nematodes (5.8%). All the collected soil samples from nectarine and plum orchards were infested with nematodes (100%), followed by citrus (97.6%), apple (88.7%), pear and quince (85.7%), and cherry (81.4%). The lowest infection (66.6%) was detected on almond and apricot. The level of infestation varied from one area to another and ranged between 0.1and 28 nematodes per 1 g of soil, with the highest number obtained on cherry. Several genera were identified based on morphological characters including:root-knot nematodes (Meloidogynespp.), Tylenchulus, Xiphinema, Rotylenchus, Pratylenchus, and Longidorus. Tylenchulus and Radopholus spp. were the most common on citrus trees, whereas Pratylechus and Meloidogyne spp. were detected almost in all the samples collected from all the crops. Six chopped aromatic plants were tested in pot experiments to control nematodes population densities. The results revealed that carbofuran (nematicide) was the most effective (88.48%) in comparison to the plant materials. Allium sativum gave the highest control (76.52%) followed by Tageta patula (72.0%), Cucurbita maxima (71.84%) and Inula viscosa (63.96%). Origanum syriacum (55.04%)d Thymus (53.72%) were less effective in comparison to the rest of tested plant materials. (author)
Pasteuria penetrans is a parasite of root-knot nematodes (Meloidogyne spp.). Infected nematodes are not killed by the bacterium, but instead of producing eggs, females produce millions of infectious endospores. In addition to sterilizing females, P. penetrans can reduce nematode infection of roots...
Höss, Sebastian; Menzel, Ralph; Gessler, Frank; Nguyen, Hang T.; Jehle, Johannes A.; Traunspurger, Walter
The genetically modified maize MON89034 × MON88017 expresses different crystal (Cry) proteins with pesticidal activity against the European corn borer (Cry1.105; Cry2Ab2) and the Western corn root worm (Cry3Bb1). Non-target organisms, such as soil nematodes, might be exposed to the Cry proteins that enter the soil in course of crop growing. Therefore, the risk of those proteins for nematodes was assessed by testing their toxic effects on Caenorhabditis elegans. All three insecticidal Cry proteins showed dose-dependent inhibitory effects on C. elegans reproduction (EC50: 0.12–0.38 μmol L −1 ), however, at concentrations that were far above the expected soil concentrations. Moreover, a reduced toxicity was observed when Cry proteins were added jointly. A C. elegans mutant strain deficient for receptors for the nematicidal Cry5B was also resistant against Cry1.105 and Cry2Ab2, suggesting that these Cry proteins bound to the same or similar receptors as nematicidal Cry proteins and thereby affect the reproduction of C. elegans. -- Highlights: •Insecticidal Cry proteins dose-dependently inhibited the reproduction of C. elegans. •Mixture toxicity was lower than expected from concentration-additive single effects. •Genes for MAPK-defense-pathway were up-regulated in presence of Cry protein mixture. •Knock-out strains deficient for Cry5B-receptors showed lower susceptibility to insecticidal Cry proteins. •Toxicity of insecticidal Cry-proteins on C. elegans occurred at concentrations far above expected field concentrations. -- Insecticidal Cry proteins expressed by genetically modified maize act on nematodes via a similar mode of action as nematicidal Cry proteins, however, at concentrations far above expected soil levels
Marek, Martin; Zouhar, Miloslav; Douda, Ondřej; Maňasová, Marie; Ryšánek, Pavel
The use of DNA-based analyses in molecular plant nematology research has dramatically increased over recent decades. Therefore, the development and adaptation of simple, robust, and cost-effective DNA purification procedures are required to address these contemporary challenges. The solid-phase-based approach developed by Flinders Technology Associates (FTA) has been shown to be a powerful technology for the preparation of DNA from different biological materials, including blood, saliva, plant tissues, and various human and plant microbial pathogens. In this work, we demonstrate, for the first time, that this FTA-based technology is a valuable, low-cost, and time-saving approach for the sampling, long-term archiving, and molecular analysis of plant-parasitic nematodes. Despite the complex structure and anatomical organization of the multicellular bodies of nematodes, we report the successful and reliable DNA-based analysis of nematode high-copy and low-copy genes using the FTA technology. This was achieved by applying nematodes to the FTA cards either in the form of a suspension of individuals, as intact or pestle-crushed nematodes, or by the direct mechanical printing of nematode-infested plant tissues. We further demonstrate that the FTA method is also suitable for the so-called "one-nematode-assay", in which the target DNA is typically analyzed from a single individual nematode. More surprisingly, a time-course experiment showed that nematode DNA can be detected specifically in the FTA-captured samples many years after initial sampling occurs. Collectively, our data clearly demonstrate the applicability and the robustness of this FTA-based approach for molecular research and diagnostics concerning phytonematodes; this research includes economically important species such as the stem nematode (Ditylenchus dipsaci), the sugar beet nematode (Heterodera schachtii), and the Northern root-knot nematode (Meloidogyne hapla).
Shapiro-Ilan, David I; Morales-Ramos, Juan A; Rojas, M Guadalupe
In nature, entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are obligate parasites of insects. The nematodes are used widely as biopesticides for suppression of insect pests. More than a dozen entomopathogenic nematode species have been commercialized for use in biological control. Most nematodes intended for commercial application are produced in artificial media via solid or liquid fermentation. However, for laboratory research and small greenhouse or field trials, in vivo production of entomopathogenic nematodes is the common method of propagation. Additionally, small companies continue to produce nematodes using in vivo methods for application in niche markets. Advances in mechanization and alternative production routes (e.g., production geared toward application of nematodes in infected host cadavers) can improve efficiency and economy of scale. The objective of this chapter is to describe basic and advanced procedures for in vivo production of entomopathogenic nematodes.
Davies, Keith G
Pasteuria penetrans is an endospore-forming bacterium, which is a hyperparasite of root-knot nematodes Meloidogyne spp. that are economically important pests of a wide range of crops. The life cycle of the bacterium and nematode are described with emphasis on the bacterium's potential as a biocontrol agent. Two aspects that currently prohibit the commercial development of the bacterium as a biocontrol agent are the inability to culture it outside its host and its host specificity. Vegetative growth of the bacterium is possible in vitro; however, getting the vegetative stages of the bacterium to enter sporogenesis has been problematic. Insights from genomic survey sequences regarding the role of cation concentration and the phosphorylation of Spo0F have proved useful in inducing vegetative bacteria to sporulate. Similarly, genomic data have also proved useful in understanding the attachment of endospores to the cuticle of infective nematode juveniles, and a Velcro-like model of spore attachment is proposed that involves collagen-like fibres on the surface of the endospore interacting with mucins on the nematode cuticle. Ecological studies of the interactions between Daphnia and Pasteuria ramosa are examined and similarities are drawn between the co-evolution of virulence in the Daphnia system and that of plant-parasitic nematodes.
Ruark, Casey L; Koenning, Stephen R; Davis, Eric L; Opperman, Charles H; Lommel, Steven A; Mitchum, Melissa G; Sit, Tim L
Five viruses were previously discovered infecting soybean cyst nematodes (SCN; Heterodera glycines) from greenhouse cultures maintained in Illinois. In this study, the five viruses [ScNV, ScPV, ScRV, ScTV, and SbCNV-5] were detected within SCN greenhouse and field populations from North Carolina (NC) and Missouri (MO). The prevalence and titers of viruses in SCN from 43 greenhouse cultures and 25 field populations were analyzed using qRT-PCR. Viral titers within SCN greenhouse cultures were similar throughout juvenile development, and the presence of viral anti-genomic RNAs within egg, second-stage juvenile (J2), and pooled J3 and J4 stages suggests active viral replication within the nematode. Viruses were found at similar or lower levels within field populations of SCN compared with greenhouse cultures of North Carolina populations. Five greenhouse cultures harbored all five known viruses whereas in most populations a mixture of fewer viruses was detected. In contrast, three greenhouse cultures of similar descent to one another did not possess any detectable viruses and primarily differed in location of the cultures (NC versus MO). Several of these SCN viruses were also detected in Heterodera trifolii (clover cyst) and Heterodera schachtii (beet cyst), but not the other cyst, root-knot, or reniform nematode species tested. Viruses were not detected within soybean host plant tissue. If nematode infection with viruses is truly more common than first considered, the potential influence on nematode biology, pathogenicity, ecology, and control warrants continued investigation.
Full Text Available The beet cyst nematode, Heterodera schachtii, is a major root pest that significantly impacts the yield of sugar beet, brassicas and related species. There has been limited molecular characterisation of this important plant pathogen: to identify target genes for its control the transcriptome of the pre-parasitic J2 stage of H. schachtii was sequenced using Roche GS FLX. Ninety seven percent of reads (i.e., 387,668 with an average PHRED score > 22 were assembled with CAP3 and CLC Genomics Workbench into 37,345 and 47,263 contigs, respectively. The transcripts were annotated by comparing with gene and genomic sequences of other nematodes and annotated proteins on public databases. The annotated transcripts were much more similar to sequences of Heterodera glycines than to those of Globodera pallida and root knot nematodes (Meloidogyne spp.. Analysis of these transcripts showed that a subset of 2,918 transcripts was common to free-living and plant parasitic nematodes suggesting that this subset is involved in general nematode metabolism and development. A set of 148 contigs and 183 singletons encoding putative homologues of effectors previously characterised for plant parasitic nematodes were also identified: these are known to be important for parasitism of host plants during migration through tissues or feeding from cells or are thought to be involved in evasion or modulation of host defences. In addition, the presence of sequences from a nematode virus is suggested. The sequencing and annotation of this transcriptome significantly adds to the genetic data available for H. schachtii, and identifies genes primed to undertake required roles in the critical pre-parasitic and early post-parasitic J2 stages. These data provide new information for identifying potential gene targets for future protection of susceptible crops against H. schachtii.
Mörck, Catarina; Elmelund-Præstekær, Louise Cathrine Braun; Kurth, Caroline
of lipid moieties for protein prenylation. The nematode Caenorhabditis elegans possesses a mevalonate pathway that lacks the branch leading to cholesterol synthesis, and thus represents an ideal organism to specifically study the noncholesterol roles of the pathway. Inhibiting HMG-CoA reductase in C....... elegans using statins or RNAi leads to developmental arrest and loss of membrane association of a GFP-based prenylation reporter. The unfolded protein response (UPR) is also strongly activated, suggesting that impaired prenylation of small GTPases leads to the accumulation of unfolded proteins and ER...... and fatty acid composition were unaffected in statin-treated worms, even though they showed reduced staining with Nile red. We conclude that inhibitors of HMG-CoA reductase or of farnesyl transferases induce the UPR by inhibiting the prenylation of M57.2 substrates, resulting in developmental arrest in C...
Zainab M. Ahmed
Full Text Available Seeds of local trees, such Azadirachta indica A. Juss, Adenanthera pavonina L., Leucaena leucocephala (Lam. de Wit and Eucalyptus spp., were used as aqueous extract at 25, 50 and 100 % concentration to control the activity of Meloidogyne javanica (Treub Citwood. All seed extracts showed lethal effect on M. javanica eggs, and a gradual decrease in egg hatching and an increase in mortality of second-stage juveniles were observed with the increase in extract concentration. L. leucocephala was found to be most effective in reducing egg hatching, whereas 100 % mortality of juveniles was observed in the case of A. indica seed extract. Number of knots was significantly reduced at 100 % concentration when seeds of chick pea and mung bean were treated and soil was drenched with A. pavonina and Eucalyptus spp. seed extract.
Preston, J F; Dickson, D W; Maruniak, J E; Nong, G; Brito, J A; Schmidt, L M; Giblin-Davis, R M
Pasteuria spp. include endospore-forming bacterial pathogens of cladoceran crustaceans and plant-parasitic nematodes. Propagation of these nematode pathogens requires attachment of soilborne endospores to nematode hosts, infection, growth, sporulation, and release of endospores to repeat the cycle of infection and propagation. The ability of these bacteria to suppress the levels of plant-parasitic nematodes in the field has made them particularly promising candidates for biocontrol of nematode diseases of plants. Genes encoding 16S ribosomal RNA have been sequenced for the cladoceran (water flea) parasite and type species, Pasteuria ramosa, and for Pasteuria spp. isolated from root-knot (Meloidogyne arenaria race 1 and Meloidogyne sp.), soybean cyst (Heterodera glycines), and sting (Belonolaimus longicaudatus) nematodes. These have provided a phylogenetic basis for their designation to a distinct clade within the family Alicyclobacillaceae of the gram-positive endospore-forming bacteria. Two apparent biotypes of P. penetrans demonstrating a host preference for different Meloidogyne spp. showed identical 16S rDNA sequences, suggesting host-recognition evolves within a given species. The sequences of genes encoding sporulation transcription factors, sigE and sigF, from P. penetrans biotype P-20 show different phylogenetic relationships to other endospore-forming bacteria, supporting their application to further discriminate Pasteuria spp. and biotypes. Distribution of an adhesin-associated epitope on polypeptides from different Pasteuria isolates provides an immunochemical approach to differentiate species and biotypes with specific host preferences. Application of bioinformatics to genomic data, as well as further characterization of the biochemical basis for host recognition, will facilitate development of Pasteuria spp. as benign alternatives to chemical nematicides.
Mohamed Youssef Banora
Full Text Available Reorganization of the microtubule network is important for the fast isodiametric expansion of giant-feeding cells induced by root-knot nematodes. The efficiency of microtubule reorganization depends on the nucleation of new microtubules, their elongation rate and activity of microtubule severing factors. New microtubules in plants are nucleated by cytoplasmic or microtubule-bound γ-tubulin ring complexes. Here we investigate the requirement of γ-tubulin complexes for giant feeding cells development using the interaction between Arabidopsis and Meloidogyne spp. as a model system. Immunocytochemical analyses demonstrate that γ-tubulin localizes to both cortical cytoplasm and mitotic microtubule arrays of the giant cells where it can associate with microtubules. The transcripts of two Arabidopsis γ-tubulin (TUBG1 and TUBG2 and two γ-tubulin complex proteins genes (GCP3 and GCP4 are upregulated in galls. Electron microscopy demonstrates association of GCP3 and γ-tubulin as part of a complex in the cytoplasm of giant cells. Knockout of either or both γ-tubulin genes results in the gene dose-dependent alteration of the morphology of feeding site and failure of nematode life cycle completion. We conclude that the γ-tubulin complex is essential for the control of microtubular network remodelling in the course of initiation and development of giant-feeding cells, and for the successful reproduction of nematodes in their plant hosts.
Lozano-Torres, Jose L.; Wilbers, Ruud H. P.; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C.; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert
Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize
Lozano-Torres, Jose L; Wilbers, Ruud H P; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert
Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize
Jose L Lozano-Torres
Full Text Available Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes
Caio Augusto Perazza
Full Text Available The objective of this research was to evaluate the contamination of infecting larvae of parasitic nematodes in cattle on Cynodon sp. pasture. The research was conducted in a milkproduction system situated in the town of Boa Esperança, in the southern region of Minas Gerais state, during the fall-winter seasons 2008. The samples of the grass were collected in ten points inserted into an outline in “W”, previously designed, in the period of morning between at 7:30 and 8:30, observing the presence of dew in all the collections performed. The samples were CUT close to the soil and separated in half, which constituted an upper and lower sample of each collecting point, their being afterwards placed into plastic bag, identified and carried to a plastic foam box . The samples were processed singly. The infecting larvae (L3 were identified and the amount per kilogram of dry matter in forage was estimated (L3/kg DM. The climatic conditions such as temperature, air relative humidity and rainfall enabled the development of the free life stages throughout the period. Even at low rainfall rates during the months of May to August, the counts of the amount of larvae in the pastures were high. Under the conditions of the dry period (Fall/Winter, the L3 forms of Cooperia sp. presented an expressive predominance in relation to the other genera throughout the period. The greatest amount of infecting larvae of this species was found in the months of July and August in the upper pasture, while for the samples of the lower part were found peaks in the months of June and August. The large number of genera of pathogenic helminths to animals in this study along the drier seasons of the year, especially in the upper pasture, demonstrates the importance of these agents as cause of losses in milk production in Minas Gerais state.
Xie, Jialian; Li, Shaojun; Mo, Chenmi; Wang, Gaofeng; Xiao, Xueqiong; Xiao, Yannong
Secreted effectors in plant root-knot nematodes (RKNs, or Meloidogyne spp.) play key roles in their parasite processes. Currently identified effectors mainly focus on the early stage of the nematode parasitism. There are only a few reports describing effectors that function in the latter stage. In this study, we identified a potential RKN effector gene, Misp12, that functioned during the latter stage of parasitism. Misp12 was unique in the Meloidogyne spp., and highly conserved in Meloidogyne incognita. It encoded a secretory protein that specifically expressed in the dorsal esophageal gland, and highly up-regulated during the female stages. Transient expression of Misp12-GUS-GFP in onion epidermal cell showed that Misp12 was localized in cytoplast. In addition, in planta RNA interference targeting Misp12 suppressed the expression of Misp12 in nematodes and attenuated parasitic ability of M. incognita. Furthermore, up-regulation of jasmonic acid (JA) and salicylic acid (SA) pathway defense-related genes in the virus-induced silencing of Misp12 plants, and down-regulation of SA pathway defense-related genes in Misp12-expressing plants indicated the gene might be associated with the suppression of the plant defense response. These results demonstrated that the novel nematode effector Misp12 played a critical role at latter parasitism of M. incognita. PMID:27446188
Darban, Daim Ali; Pathan, Mumtaz Ali; Bhatti, Abdul Ghaffar; Maitelo, Sultan Ahmed
Pasteuria penetrans will build-up faster where there is a high initial nematode density and can suppress root-knot nematode populations in the roots of tomato plants. The effect of different initial densities of nematode (Meloidogyne javanica) (150, 750, 1500, 3000) and P. penetrans infected females (F1, F3) densities (F0=control and AC=absolute control without nematode or P. penetrans inoculum) on the build-up of Pasteuria population was investigated over four crop cycles. Two major points of interest were highlighted. First, that within a confined soil volume, densities of P. penetrans can increase >100 times within 2 or 3 crop cycles. Second, from a relatively small amount of spore inoculum, infection of the host is very high. There were more infected females in the higher P. penetrans doses. The root growth data confirms the greater number of females in the controls particularly at the higher inoculum densities in the third and fourth crops. P. penetrans generally caused the fresh root weights to be higher than those in the control. P. penetrans has shown greater reduction of egg masses per plant at most densities. The effects of different initial densities of M. javanica and P. penetrans on the development of the pest and parasite populations were monitored. And no attempt was made to return the P. penetrans spores to the pots after each crop so the build-up in actual numbers of infected females and spores under natural conditions may be underestimated.
Phani, Victor; Shivakumara, Tagginahalli N; Davies, Keith G; Rao, Uma
Root-knot nematode (RKN) Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans , is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition, development and reproduction; they are also a component of the nematode cuticle and thought to be involved in the interface between hosts and parasites. Attachment of endospores to the cuticle of second stage juveniles of RKN is the primary step of infection and several factors have been identified to facilitate attachment. In this study, the full length of Mi-far-1 (573 bp) was cloned from M. incognita and characterized. Analysis revealed that the Mi-far-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a glycosylation site. Quantitative PCR showed the highest expression in the fourth stage juveniles and in situ hybridization revealed the presence of Mi-far-1 mRNA in the hypodermis below the cuticle. Single copy insertion pattern of Mi-far-1 in M. incognita genome was detected by Southern blotting. Knockdown of Mi-far-1 showed significantly increased attachment of P. penetrans' endospores on juvenile cuticle surface and also affected host finding, root infection and nematode fecundity.
Full Text Available Root-knot nematode (RKN Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans, is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition, development and reproduction; they are also a component of the nematode cuticle and thought to be involved in the interface between hosts and parasites. Attachment of endospores to the cuticle of second stage juveniles of RKN is the primary step of infection and several factors have been identified to facilitate attachment. In this study, the full length of Mi-far-1 (573 bp was cloned from M. incognita and characterized. Analysis revealed that the Mi-far-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a glycosylation site. Quantitative PCR showed the highest expression in the fourth stage juveniles and in situ hybridization revealed the presence of Mi-far-1 mRNA in the hypodermis below the cuticle. Single copy insertion pattern of Mi-far-1 in M. incognita genome was detected by Southern blotting. Knockdown of Mi-far-1 showed significantly increased attachment of P. penetrans’ endospores on juvenile cuticle surface and also affected host finding, root infection and nematode fecundity.
Full Text Available Plant-parasitic nematodes cause considerable damage to crop plants. The rhizosphere microbiome can affect invasion and reproductive success of plant-parasitic nematodes, thus affecting plant damage. In this study, we investigated how the transplanted rhizosphere microbiome from different crops affect plant-parasitic nematodes on soybean or tomato, and whether the plant’s own microbiome from the rhizosphere protects it better than the microbiome from fallow soil. Soybean plants growing in sterilized substrate were inoculated with the microbiome extracted from the rhizosphere of soybean, maize, or tomato. Controls were inoculated with extracts from bulk soil, or not inoculated. After the microbiome was established, the root lesion nematode Pratylenchus penetrans was added. Root invasion of P. penetrans was significantly reduced on soybean plants inoculated with the microbiome from maize or soybean compared to tomato or bulk soil, or the uninoculated control. In the analogous experiment with tomato plants inoculated with either P. penetrans or the root knot nematode Meloidogyne incognita, the rhizosphere microbiomes of maize and tomato reduced root invasion by P. penetrans and M. incognita compared to microbiomes from soybean or bulk soil. Reproduction of M. incognita on tomato followed the same trend, and it was best suppressed by the tomato rhizosphere microbiome. In split-root experiments with soybean and tomato plants, a systemic effect of the inoculated rhizosphere microbiomes on root invasion of P. penetrans was shown. Furthermore, some transplanted microbiomes slightly enhanced plant growth compared to uninoculated plants. The microbiomes from maize rhizosphere and bulk soil increased the fresh weights of roots and shoots of soybean plants, and microbiomes from soybean rhizosphere and bulk soil increased the fresh weights of roots and shoots of tomato plants. Nematode invasion did not affect plant growth in these short-term experiments. In
Li, Juan; Zou, Chenggang; Xu, Jianping; Ji, Xinglai; Niu, Xuemei; Yang, Jinkui; Huang, Xiaowei; Zhang, Ke-Qin
Plant-parasitic nematodes cause significant damage to a broad range of vegetables and agricultural crops throughout the world. As the natural enemies of nematodes, nematophagous microorganisms offer a promising approach to control the nematode pests. Some of these microorganisms produce traps to capture and kill the worms from the outside. Others act as internal parasites to produce toxins and virulence factors to kill the nematodes from within. Understanding the molecular basis of microbe-nematode interactions provides crucial insights for developing effective biological control agents against plant-parasitic nematodes. Here, we review recent advances in our understanding of the interactions between nematodes and nematophagous microorganisms, with a focus on the molecular mechanisms by which nematophagous microorganisms infect nematodes and on the nematode defense against pathogenic attacks. We conclude by discussing several key areas for future research and development, including potential approaches to apply our recent understandings to develop effective biocontrol strategies.
also the use of chicken manure on control of root-knot nematodes was very effective and even caused IGR in tomato production. _____________________________ Conclusion. 1-\tIt was found that, the use of organic matters, chicken manure, municipal compost, vermicompost; waste cabbage leaves and farm manure in different amounts control the SBCN population accordingly. 2-\tTherefore, it is suggested here, that chicken manure at 20t/ha, is for an optimum use and economically reasonable and significant amount for the SBCN control. 3-\tAlso composts 015 and 08, vermicompost, farm manure and waste cabbage leaf at 40 to 60t/h, in terms of economic value appears to be applicable. 4- Always a method or a substance, in terms of its own hazards is not recommended. Therefore, any of the said material can be used in intervals for SBCN control and or in integration with other methods such as crop rotation, disease scape,
Full Text Available Banana production is seriously hindered by Meloidogyne spp. all over the world. Endophytes are ideal candidates compared to pesticides as an environmentally benign agent. In the present study, endophytes isolated from banana roots infected by Meloidogyne spp. with different disease levels were tested in vitro, and in sterile and nature banana monoculture soils against Meloidogyne javanica. The proportion of antagonistic endophytes were higher in the roots of middle and high disease levels. Among those, bacteria were dominant, and Pseudomonas spp., Bacillus spp. and Streptomyces spp. showed more abundant populations. One strain, named as SA, with definite root inner-colonization ability was isolated and identified as Streptomyces sp. This strain showed an inhibiting rate of >50% in vitro and biocontrol efficiency of 70.7% in sterile soil against Meloidogyne javanica, compared to the control. Greenhouse experiment results showed that the strain SA exhibits excellent biological control ability for plant-parasites both in roots and in root-knot nematode infested soil. SA treatment showed a higher number of bacterivores, especially Mesorhabditis and Cephalobus. The maturity index was significantly lower, while enrichment index (EI was significantly higher in the SA treatment. In conclusion, this study presents an important potential application of the endophytic strain Streptomyces sp. for the control of plant-parasitic nematodes, especially Meloidogyne javanica, and presents the effects on the associated variation of the nematode community.
Medeiros, Hugo Agripino de; Araújo Filho, Jerônimo Vieira de; Freitas, Leandro Grassi de; Castillo, Pablo; Rubio, María Belén; Hermosa, Rosa; Monte, Enrique
Root-knot nematodes (RKN) are major crop pathogens worldwide. Trichoderma genus fungi are recognized biocontrol agents and a direct activity of Trichoderma atroviride (Ta) against the RKN Meloidogyne javanica (Mj), in terms of 42% reduction of number of galls (NG), 60% of number of egg masses and 90% of number of adult nematodes inside the roots, has been observed in tomato grown under greenhouse conditions. An in vivo split-root designed experiment served to demonstrate that Ta induces systemic resistance towards Mj, without the need for the organisms to be in direct contact, and significantly reduces NG (20%) and adult nematodes inside tomato roots (87%). The first generation (F1) of Ta-primed tomato plants inherited resistance to RKN; although, the induction of defenses occurred through different mechanisms, and in varying degrees, depending on the Ta-Mj interaction. Plant growth promotion induced by Ta was inherited without compromising the level of resistance to Mj, as the progeny of Ta-primed plants displayed increased size and resistance to Mj without fitness costs. Gene expression results from the defense inductions in the offspring of Ta-primed plants, suggested that an auxin-induced reactive oxygen species production promoted by Ta may act as a major defense strategy during plant growth.
Schmidt, Liesbeth M.; Mouton, Laurence; Nong, Guang; Ebert, Dieter; Preston, James F.
Pasteuria penetrans, an obligate endospore-forming parasite of Meloidogyne spp. (root knot nematodes), has been identified as a promising agent for biocontrol of these destructive agricultural crop pests. Pasteuria ramosa, an obligate parasite of water fleas (Daphnia spp.), has been shown to modulate cladoceran populations in natural ecosystems. Selected sporulation genes and an epitope associated with the spore envelope of these related species were compared. The sigE and spoIIAA/spoIIAB genes differentiate the two species to a greater extent than 16S rRNA and may serve as probes to differentiate the species. Single-nucleotide variations were observed in several conserved genes of five distinct populations of P. ramosa, and while most of these variations are silent single-nucleotide polymorphisms, a few result in conservative amino acid substitutions. A monoclonal antibody directed against an adhesin epitope present on P. penetrans P20 endospores, previously determined to be specific for Pasteuria spp. associated with several phytopathogenic nematodes, also detects an epitope associated with P. ramosa endospores. Immunoblotting provided patterns that differentiate P. ramosa from other Pasteuria spp. This monoclonal antibody thus provides a probe with which to detect and discriminate endospores of different Pasteuria spp. The presence of a shared adhesin epitope in two species with such ecologically distant hosts suggests that there is an ancient and ecologically significant recognition process in these endospore-forming bacilli that contributes to the virulence of both species in their respective hosts. PMID:17933927
Schmidt, Liesbeth M; Mouton, Laurence; Nong, Guang; Ebert, Dieter; Preston, James F
Pasteuria penetrans, an obligate endospore-forming parasite of Meloidogyne spp. (root knot nematodes), has been identified as a promising agent for biocontrol of these destructive agricultural crop pests. Pasteuria ramosa, an obligate parasite of water fleas (Daphnia spp.), has been shown to modulate cladoceran populations in natural ecosystems. Selected sporulation genes and an epitope associated with the spore envelope of these related species were compared. The sigE and spoIIAA/spoIIAB genes differentiate the two species to a greater extent than 16S rRNA and may serve as probes to differentiate the species. Single-nucleotide variations were observed in several conserved genes of five distinct populations of P. ramosa, and while most of these variations are silent single-nucleotide polymorphisms, a few result in conservative amino acid substitutions. A monoclonal antibody directed against an adhesin epitope present on P. penetrans P20 endospores, previously determined to be specific for Pasteuria spp. associated with several phytopathogenic nematodes, also detects an epitope associated with P. ramosa endospores. Immunoblotting provided patterns that differentiate P. ramosa from other Pasteuria spp. This monoclonal antibody thus provides a probe with which to detect and discriminate endospores of different Pasteuria spp. The presence of a shared adhesin epitope in two species with such ecologically distant hosts suggests that there is an ancient and ecologically significant recognition process in these endospore-forming bacilli that contributes to the virulence of both species in their respective hosts.
Crops under greenhouses offer the possibility of vegetables production of high added value by focusing on earliness. They help to spread the availability timing of vegetables and fruits in the market throughout the year. However, these crops are subject to numerous attacks entailing heavy losses of yield quantity and quality. The plant parasitic nematodes especially rot-knot nematodes of the genus Meloidogyne are considered dangerous enemies of these cultures. The evolution study of these nematodes in different soil types allows one to compare the migration and movement of these nematodes in sandy soils considered as light soils, in clay soils heavy and intermediate silty clay soils. These soils have also rates of organic matter and a percentage of magnesium and calcium that might provide better conditions to the survival and migration of second stage larvae inoculated at a rate of 650 juveniles per pot of 24 cm in diameter where plants of melon Cucumis melo var. (Charentais) known to be susceptible to Meloidogyne was cultivated. The results for the population development of Meloidogyne, after a growing period of 3 months show an increase in the number of eggs, juvenile stages, inflated, swollen females and males in the 3 types of soil and that independently of clay fraction although clay soil may asphyxiate Meloidogyne. The development of the three species of Meloidogyne studied in these soils, the parameters taken into consideration (index of galls, which were 1.58, 1.75 and 1.5 for the sandy clay and the middle ground soils, vigour index and the evolution of populations of Meloidogyne and roots and soil as well as parameters related to production reveal the adaptation of these root-knot nematodes to the clay and sandy loam soils. At the end of culture, the final populations are important in the soils studied; 2680 for soil S. (sandy), 2272 for soil A (clay) and 2327 for soil I (intermediate) with a multiplication rate almost similar ( 4.12, 3.49 and 3
Bajaj H. K.
Full Text Available Biology of Fictor composticola has been studied on Aphelenchus avenae in vitro. It reproduces by amphimixis, embryonic development is completed in 24 - 27 h and life cycle in 3 - 4 days. Fusion of sperm and egg pronuclei occurs in the uteri. Pulsation of median oesophageal bulb and pressing of lips against egg shell is seen just prior to hatching but teeth seem to play no role in this process. No moulting occurs inside the egg shell and the first stage juvenile hatches out. Female and male undergo mating upon addition of water in the culture plates and continue to swim in copula for a considerable time. A female lays 1.6 - 4.0 eggs in 24 h while feeding upon A. radicicolus. Predation and reproduction is affected by the temperature and 25 - 35 °C is the optimum range for these phenomena. Process of feeding as recorded with a CCTV attached to a compound microscope is described. F. composticola engulfs small preys; sucks the intestinal contents while holding them or cuts the body wall of large-sized preys and then feeds on prolapsed organs. Two sexes differ in their efficiencies of predation, a female on an average kills 53 A. avenae as compared to 11 by a male in 24 h. F. composticola feeds and reproduces on mycophagous nematodes and juveniles of root- knot, cyst and citrus nematodes but does not prey upon adult nematodes having coarsely annulated cuticle. Cannibalism in this species is also observed. F. composticola and Seinura paratenuicaudata prey upon each other. Biocontrol potential of F. composticola for managing nematode problems in button mushroom and agricultural crops has also been discussed.
Buskov, S; Serra, B; Rosa, E; Sørensen, H; Sørensen, J C
The potato cyst nematode (Globodera rostochiensis cv. Woll) is responsible for large yield losses in the potato crop, and opportunities for reducing the attack of these plant nematode species are, therefore, important. This study has been devoted to the testing of the in vitro effects on the potato cyst nematode of eight glucosinolates [prop-2-enyl-, but-3-enyl-, (R)-4-methylsulfinylbut-3-enyl-, benzyl-, phenethyl-, 4-hydroxybenzyl-, (2S)-2-hydroxybut-3-enyl-, and (2R)-2-hydroxy-2-phenylethylglucosinolate] as well as the effects of the products of this myrosinase-catalyzed hydrolysis. The glucosinolates were used at three concentrations, 0.05, 0.3, and 1.0 mg/mL, in the presence or absence of the enzyme myrosinase. The effects of the compounds on the mortality were monitored every 8 h for a 72 h period. No effects were found for any of the intact glucosinolates. However, when active myrosinase was included with 1 mg/mL phenethylglucosinolate at pH 6.5, 100% mortality was observed within just 16 h. A similar effect was achieved at the same concentration of benzyl- and prop-2-enylglucosinolates in the myrosinase-containing solutions, although longer exposures were required (24 and 40 h, respectively). The main aglucone products released from the glucosinolates with pronounced effects on the nematodes were shown to be the corresponding isothiocyanates. The results suggest that mixtures of these specific glucosinolates and active myrosinase or autolysis of plant materials containing these enzymes and glucosinolates might be used to control the potato cyst nematode in the soil.
Casey L Ruark
Full Text Available Five viruses were previously discovered infecting soybean cyst nematodes (SCN; Heterodera glycines from greenhouse cultures maintained in Illinois. In this study, the five viruses [ScNV, ScPV, ScRV, ScTV, and SbCNV-5] were detected within SCN greenhouse and field populations from North Carolina (NC and Missouri (MO. The prevalence and titers of viruses in SCN from 43 greenhouse cultures and 25 field populations were analyzed using qRT-PCR. Viral titers within SCN greenhouse cultures were similar throughout juvenile development, and the presence of viral anti-genomic RNAs within egg, second-stage juvenile (J2, and pooled J3 and J4 stages suggests active viral replication within the nematode. Viruses were found at similar or lower levels within field populations of SCN compared with greenhouse cultures of North Carolina populations. Five greenhouse cultures harbored all five known viruses whereas in most populations a mixture of fewer viruses was detected. In contrast, three greenhouse cultures of similar descent to one another did not possess any detectable viruses and primarily differed in location of the cultures (NC versus MO. Several of these SCN viruses were also detected in Heterodera trifolii (clover cyst and Heterodera schachtii (beet cyst, but not the other cyst, root-knot, or reniform nematode species tested. Viruses were not detected within soybean host plant tissue. If nematode infection with viruses is truly more common than first considered, the potential influence on nematode biology, pathogenicity, ecology, and control warrants continued investigation.
Subbotin, S A; Vierstraete, A; De Ley, P; Rowe, J; Waeyenberge, L; Moens, M; Vanfleteren, J R
The ITS1, ITS2, and 5.8S gene sequences of nuclear ribosomal DNA from 40 taxa of the family Heteroderidae (including the genera Afenestrata, Cactodera, Heterodera, Globodera, Punctodera, Meloidodera, Cryphodera, and Thecavermiculatus) were sequenced and analyzed. The ITS regions displayed high levels of sequence divergence within Heteroderinae and compared to outgroup taxa. Unlike recent findings in root knot nematodes, ITS sequence polymorphism does not appear to complicate phylogenetic analysis of cyst nematodes. Phylogenetic analyses with maximum-parsimony, minimum-evolution, and maximum-likelihood methods were performed with a range of computer alignments, including elision and culled alignments. All multiple alignments and phylogenetic methods yielded similar basic structure for phylogenetic relationships of Heteroderidae. The cyst-forming nematodes are represented by six main clades corresponding to morphological characters and host specialization, with certain clades assuming different positions depending on alignment procedure and/or method of phylogenetic inference. Hypotheses of monophyly of Punctoderinae and Heteroderinae are, respectively, strongly and moderately supported by the ITS data across most alignments. Close relationships were revealed between the Avenae and the Sacchari groups and between the Humuli group and the species H. salixophila within Heteroderinae. The Goettingiana group occupies a basal position within this subfamily. The validity of the genera Afenestrata and Bidera was tested and is discussed based on molecular data. We conclude that ITS sequence data are appropriate for studies of relationships within the different species groups and less so for recovery of more ancient speciations within Heteroderidae. Copyright 2001 Academic Press.
Full Text Available Phyto-endoparasitic nematodes induce specialized feeding cells (NFCs in their hosts, termed syncytia and giant cells (GCs for cyst and root-knot nematodes, respectively. They differ in their ontogeny and global transcriptional signatures, but both develop cell wall ingrowths to facilitate high rates of apoplastic/symplastic solute exchange showing transfer cell (TC characteristics. Regulatory signals for TC differentiation are not still well known. The two-component signalling system (2CS and reactive oxygen species are proposed as inductors of TC identity, while, 2CSs-related genes are not major contributors to differential gene expression in early developing NFCs. Additionally, transcriptomic and functional studies have assigned a major role to auxin and ethylene as regulatory signals on early developing TCs. Genes encoding proteins with similar functions expressed in both early developing NFCs and typical TCs are putatively involved in upstream or downstream responses mediated by auxin and ethylene. Yet, no function directly associated to the TCs identity of NFCs, such as the formation of cell wall ingrowths is described for most of them. Thus we reviewed similarities between transcriptional changes observed during the early stages of NFCs formation and those described during differentiation of TCs to hypothesize about putative signals leading to TC-like differentiation of NFCs with particular emphasis on auxin an ethylene.
Juan Carlos Álvarez-Hernández
Full Text Available Cucurbita maxima x Cucurbita moschata rootstock are used to prevent infection with Fusarium oxysporum f. sp. niveum in watermelon production; however, this rootstock is not effective against nematode attack. Because of their vigor, the grafted plants can be planted at lower plant densities than the non-grafted plants. The tolerance to Fusarium oxysporum f. sp. niveum and Meloidogyne incognita was assessed in watermelon plants grafted onto a hybrid of Citrullus lanatus cv Robusta or the Cucurbita maxima x Cucurbita moschata cv Super Shintoza rootstocks. The densities of plants were 2083 and 4166 plants ha-1. Non-grafted watermelons were the controls. The Crunchy Red and Sangría watermelon cultivars were used as the scions, it the latter as a pollinator. The experiments were performed for two production cycles in soils infested with Fusarium oxysporum f. sp. niveum and Meloidogyne incognita. The incidence of Fusarium oxysporum f. sp. niveum was significantly greater in the non-grafted than in the grafted plants. The grafted plants presented similar resistance to Fusarium regardless of the rootstock. The root-knot galling index for Meloidogyne incognita was significantly lower in plants grafted onto Citrullus lanatus cv Robusta than onto the other rootstock. The yields of plants grafted onto Citrullus lanatus cv Robusta grown at both plant densities were significantly higher than in the other treatments.
Kyndt, Tina; Haegeman, Annelies; Gheysen, Godelieve
Endo-1,4-beta-glucanases or cellulases from the glycosyl hydrolase family 5 (GHF5) have been found in numerous bacteria and fungi, and recently also in higher eukaryotes, particularly in plant-parasitic nematodes (PPN). The origin of these genes has been attributed to horizontal gene transfer from bacteria, although there still is a lot of uncertainty about the origin and structure of the ancestral GHF5 PPN endoglucanase. It is not clear whether this ancestral endoglucanase consisted of the whole gene cassette, containing a catalytic domain and a carbohydrate-binding module (CBM, type 2 in PPN and bacteria) or only of the catalytic domain while the CBM2 was retrieved by domain shuffling later in evolution. Previous studies on the evolution of these genes have focused primarily on data of sedentary nematodes, while in this study, extra data from migratory nematodes were included. Two new endoglucanases from the migratory nematodes Pratylenchus coffeae and Ditylenchus africanus were included in this study. The latter one is the first gene isolated from a PPN of a different superfamily (Sphaerularioidea); all previously known nematode endoglucanases belong to the superfamily Tylenchoidea (order Rhabditida). Phylogenetic analyses were conducted with the PPN GHF5 endoglucanases and homologous endoglucanases from bacterial and other eukaryotic lineages such as beetles, fungi and plants. No statistical incongruence between the phylogenetic trees deduced from the catalytic domain and the CBM2 was found, which could suggest that both domains have evolved together. Furthermore, based on gene structure data, we inferred a model for the evolution of the GHF5 endoglucanase gene structure in plant-parasitic nematodes. Our data confirm a close relationship between Pratylenchus spp. and the root knot nematodes, while some Radopholus similis endoglucanases are more similar to cyst nematode genes. We conclude that the ancestral PPN GHF5 endoglucanase gene most probably consisted of
Full Text Available Abstract Background Endo-1,4-beta-glucanases or cellulases from the glycosyl hydrolase family 5 (GHF5 have been found in numerous bacteria and fungi, and recently also in higher eukaryotes, particularly in plant-parasitic nematodes (PPN. The origin of these genes has been attributed to horizontal gene transfer from bacteria, although there still is a lot of uncertainty about the origin and structure of the ancestral GHF5 PPN endoglucanase. It is not clear whether this ancestral endoglucanase consisted of the whole gene cassette, containing a catalytic domain and a carbohydrate-binding module (CBM, type 2 in PPN and bacteria or only of the catalytic domain while the CBM2 was retrieved by domain shuffling later in evolution. Previous studies on the evolution of these genes have focused primarily on data of sedentary nematodes, while in this study, extra data from migratory nematodes were included. Results Two new endoglucanases from the migratory nematodes Pratylenchus coffeae and Ditylenchus africanus were included in this study. The latter one is the first gene isolated from a PPN of a different superfamily (Sphaerularioidea; all previously known nematode endoglucanases belong to the superfamily Tylenchoidea (order Rhabditida. Phylogenetic analyses were conducted with the PPN GHF5 endoglucanases and homologous endoglucanases from bacterial and other eukaryotic lineages such as beetles, fungi and plants. No statistical incongruence between the phylogenetic trees deduced from the catalytic domain and the CBM2 was found, which could suggest that both domains have evolved together. Furthermore, based on gene structure data, we inferred a model for the evolution of the GHF5 endoglucanase gene structure in plant-parasitic nematodes. Our data confirm a close relationship between Pratylenchus spp. and the root knot nematodes, while some Radopholus similis endoglucanases are more similar to cyst nematode genes. Conclusion We conclude that the ancestral
Yadav, Shruti; Shokal, Upasana; Forst, Steven; Eleftherianos, Ioannis
Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophila rpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.
Full Text Available Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2 of plant parasitic Meloidogyne spp. and infective juveniles (IJs of entomopathogenic nematodes (EPN, e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9. A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9 and C. elegans (ascr#2 dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.
Full Text Available Root-knot nematodes (genus Meloidogyne exhibit a diversity of reproductive modes ranging from obligatory sexual to fully asexual reproduction. Intriguingly, the most widespread and devastating species to global agriculture are those that reproduce asexually, without meiosis. To disentangle this surprising parasitic success despite the absence of sex and genetic exchanges, we have sequenced and assembled the genomes of three obligatory ameiotic and asexual Meloidogyne. We have compared them to those of relatives able to perform meiosis and sexual reproduction. We show that the genomes of ameiotic asexual Meloidogyne are large, polyploid and made of duplicated regions with a high within-species average nucleotide divergence of ~8%. Phylogenomic analysis of the genes present in these duplicated regions suggests that they originated from multiple hybridization events and are thus homoeologs. We found that up to 22% of homoeologous gene pairs were under positive selection and these genes covered a wide spectrum of predicted functional categories. To biologically assess functional divergence, we compared expression patterns of homoeologous gene pairs across developmental life stages using an RNAseq approach in the most economically important asexually-reproducing nematode. We showed that >60% of homoeologous gene pairs display diverged expression patterns. These results suggest a substantial functional impact of the genome structure. Contrasting with high within-species nuclear genome divergence, mitochondrial genome divergence between the three ameiotic asexuals was very low, signifying that these putative hybrids share a recent common maternal ancestor. Transposable elements (TE cover a ~1.7 times higher proportion of the genomes of the ameiotic asexual Meloidogyne compared to the sexual relative and might also participate in their plasticity. The intriguing parasitic success of asexually-reproducing Meloidogyne species could be partly explained by
Djian-Caporalino, Caroline; Palloix, Alain; Fazari, Ariane; Marteu, Nathalie; Barbary, Arnaud; Abad, Pierre; Sage-Palloix, Anne-Marie; Mateille, Thierry; Risso, Sabine; Lanza, Roger; Taussig, Catherine; Castagnone-Sereno, Philippe
Resistant cultivars are key elements for pathogen control and pesticide reduction, but their repeated use may lead to the emergence of virulent pathogen populations, able to overcome the resistance. Increased research efforts, mainly based on theoretical studies, explore spatio-temporal deployment strategies of resistance genes in order to maximize their durability. We evaluated experimentally three of these strategies to control root-knot nematodes: cultivar mixtures, alternating and pyramiding resistance genes, under controlled and field conditions over a 3-years period, assessing the efficiency and the durability of resistance in a protected crop rotation system with pepper as summer crop and lettuce as winter crop. The choice of the resistance gene and the genetic background in which it is introgressed, affected the frequency of resistance breakdown. The pyramiding of two different resistance genes in one genotype suppressed the emergence of virulent isolates. Alternating different resistance genes in rotation was also efficient to decrease virulent populations in fields due to the specificity of the virulence and the trapping effect of resistant plants. Mixing resistant cultivars together appeared as a less efficient strategy to control nematodes. This work provides experimental evidence that, in a cropping system with seasonal sequences of vegetable species, pyramiding or alternating resistance genes benefit yields in the long-term by increasing the durability of resistant cultivars and improving the long-term control of a soil-borne pest. To our knowledge, this result is the first one obtained for a plant-nematode interaction, which helps demonstrate the general applicability of such strategies for breeding and sustainable management of resistant cultivars against pathogens.
Cabrera, Javier; Fenoll, Carmen; Escobar, Carolina
Plant endoparasitic nematodes, root-knot and cyst nematodes (RKNs and CNs) induce within the root vascular cylinder transfer cells used for nourishing, termed giant cells (GCs) and syncytia. Understanding the molecular mechanisms behind this process is essential to develop tools for nematode control. Based on the crucial role in gall development of LBD16, also a key component of the auxin pathway leading to the divisions in the xylem pole pericycle during lateral root (LR) formation, we investigated genes co-regulated with LBD16 in different transcriptomes and analyzed their similarities and differences with those of RKNs and CNs feeding sites (FS). This analysis confirmed LBD16 and its co-regulated genes, integrated in signaling cascades mediated by auxins during LR and callus formation, as a particular feature of RKN-FS distinct to CNs. However, LBD16, and its positively co-regulated genes, were repressed in syncytia, suggesting a selective down- regulation of the LBD16 auxin mediated pathways in CNs-FS. Interestingly, cytokinin-induced genes are enriched in syncytia and we encountered similarities between the transcriptome of shoot regeneration from callus, modulated by cytokinins, and that of syncytia. These findings establish differences in the regulatory networks leading to both FS formation, probably modulated by the auxin/cytokinin balance.
Tucker, Mark L; Xue, Ping; Yang, Ronghui
Colonization of plant roots by root knot and cyst nematodes requires a functional ethylene response pathway. However, ethylene plays many roles in root development and whether its role in nematode colonization is direct or indirect, for example lateral root initiation or root hair growth, is not known. The temporal requirement for ethylene and localized synthesis of ethylene during the life span of soybean cyst nematode (SCN) on soybean roots was further investigated. Although a significant increase in ethylene evolution was not detected from SCN-colonized roots, the concentration of the immediate precursor to ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC), was higher in SCN-colonized root pieces and root tips than in other parts of the root. Moreover, expression analysis of 17 ACC synthase (ACS) genes indicated that a select set of ACS genes is expressed in SCN-colonized root pieces that is clearly different from the set of genes expressed in non-colonized roots or root tips. Semi-quantitative real-time PCR indicated that ACS transcript accumulation correlates with the high concentration of ACC in root tips. In addition, an ACS-like sequence was found in the public SCN nucleotide database. Acquisition of a full-length sequence for this mRNA (accession GQ389647) and alignment with transcripts for other well-characterized ACS proteins indicated that the nematode sequence is missing a key element required for ACS activity and therefore probably is not a functional ACS. Moreover, no significant amount of ACC was found in any growth stage of SCN that was tested.
Jiang, Xiangzhi; Xiang, Meichun; Liu, Xingzhong
Nematode-trapping fungi are a unique and intriguing group of carnivorous microorganisms that can trap and digest nematodes by means of specialized trapping structures. They can develop diverse trapping devices, such as adhesive hyphae, adhesive knobs, adhesive networks, constricting rings, and nonconstricting rings. Nematode-trapping fungi have been found in all regions of the world, from the tropics to Antarctica, from terrestrial to aquatic ecosystems. They play an important ecological role in regulating nematode dynamics in soil. Molecular phylogenetic studies have shown that the majority of nematode-trapping fungi belong to a monophyletic group in the order Orbiliales (Ascomycota). Nematode-trapping fungi serve as an excellent model system for understanding fungal evolution and interaction between fungi and nematodes. With the development of molecular techniques and genome sequencing, their evolutionary origins and divergence, and the mechanisms underlying fungus-nematode interactions have been well studied. In recent decades, an increasing concern about the environmental hazards of using chemical nematicides has led to the application of these biological control agents as a rapidly developing component of crop protection.
Kenney, Eric; Eleftherianos, Ioannis
Plant-parasitic nematodes are responsible for substantial damages within the agriculture industry every year, which is a challenge that has thus far gone largely unimpeded. Chemical nematicides have been employed with varying degrees of success, but their implementation can be cumbersome, and furthermore they could potentially be neutralising an otherwise positive effect from the entomopathogenic nematodes that coexist with plant-parasitic nematodes in soil environments and provide protection for plants against insect pests. Recent research has explored the potential of employing entomopathogenic nematodes to protect plants from plant-parasitic nematodes, while providing their standard degree of protection against insects. The interactions involved are highly complex, due to both the three-organism system and the assortment of variables present in a soil environment, but a strong collection of evidence has accumulated regarding the suppressive capacity of certain entomopathogenic nematodes and their mutualistic bacteria, in the context of limiting the infectivity of plant-parasitic nematodes. Specific factors produced by certain entomopathogenic nematode complexes during the process of insect infection appear to have a selectively nematicidal, or at least repellant, effect on plant-parasitic nematodes. Using this information, an opportunity has formed to adapt this relationship to large-scale, field conditions and potentially relieve the agricultural industry of one of its most substantial burdens. Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.
Soybeans [Glycine max] are the second largest cash crop in US Agriculture, but the soybean yield is compromised by infections from Heterodera glycines, also known as Soybean Cyst Nematodes [SCN]. SCN are the most devastating pathogen or plant disease soybean producers confront. This obligate parasi...
Nematode acetylcholine (ACh) receptors were characterized using both biochemical and electrophysiological techniques, including: (1) receptor binding studies in crude homogenates of the free-living nematode Caenorhabditis elegans and the parasitic nematode Ascaris lumbricoides with the high-affinity probe [ 3 H]N-methylscopolamine ([ 3 H]NMS) which binds to muscarinic receptors in many vertebrate and invertebrate tissues (2) measurement of depolarization and contraction induced by a variety of cholinergic agents, including N-methylscopolamine (NMS), in an innervated dorsal muscle strip preparation of Ascaris; (3) examination of the antagonistic actions of d-tubocurarine (dTC) and NMS at dorsal neuromuscular junction; (4) measurement of input resistance changes in Ascaris commissural motorneurons induced by ACh, dTC, NMS, pilocarpine and other cholinergic drugs
Rehman, Sajid; Gupta, Vijai K; Goyal, Aakash K
Plant parasitic nematodes develop an intimate and long-term feeding relationship with their host plants. They induce a multi-nucleate feeding site close to the vascular bundle in the roots of their host plant and remain sessile for the rest of their life. Nematode secretions, produced in the oesophageal glands and secreted through a hollow stylet into the host plant cytoplasm, are believed to play key role in pathogenesis. To combat these persistent pathogens, the identity and functional analysis of secreted effectors can serve as a key to devise durable control measures. In this review, we will recapitulate the knowledge over the identification and functional characterization of secreted nematode effector repertoire from phytoparasitic nematodes. Despite considerable efforts, the identity of genes encoding nematode secreted proteins has long been severely hampered because of their microscopic size, long generation time and obligate biotrophic nature. The methodologies such as bioinformatics, protein structure modeling, in situ hybridization microscopy, and protein-protein interaction have been used to identify and to attribute functions to the effectors. In addition, RNA interference (RNAi) has been instrumental to decipher the role of the genes encoding secreted effectors necessary for parasitism and genes attributed to normal development. Recent comparative and functional genomic approaches have accelerated the identification of effectors from phytoparasitic nematodes and offers opportunities to control these pathogens. Plant parasitic nematodes pose a serious threat to global food security of various economically important crops. There is a wealth of genomic and transcriptomic information available on plant parasitic nematodes and comparative genomics has identified many effectors. Bioengineering crops with dsRNA of phytonematode genes can disrupt the life cycle of parasitic nematodes and therefore holds great promise to develop resistant crops against plant
Luiz Gonzaga E. Lordello
Full Text Available Entre os sérios fatôres que atuam contra a expansão da cultura da soja no Estado de São Paulo, acha-se o representado por nematóides parasitos. Dêstes, os que mais têm atraído a atenção dos cultivadores e fitopatologistas são as espécies formadoras de galhas no sistema radicular (Meloidogyne spp.. O estudo do material atacado coligido em Bauru revelou que, naquela região, três formas se acham envolvidas, a saber : Pratylenchus sp., Meloidogyne incognita (Kofoid & White, 1919 Chitwood, 1949 e M. javanica bauruensis n. subsp. Neste trabalho é estudada a nova subespécie, sendo também apresentadas algumas observações sobre a população de M. incognita.One of the serious detriments to soybean (Glycine max (L. Merr. cultivation in the State of S. Paulo, Brazil, are root-parasitic nematodes. A study of infected material collected at Bauru, where at least two distinct soybean varieties were cultivated, disclosed that three forms were involved: a meadow nematode (Pralylenchus sp. and two root-knot nematodes (Meloidogyne incognita (Kofoid & White, 1919 Chitwood, 1949, and M. javanica bauruensis n. subsp.. Silva, Lordello & Miyasaka (3 published some observations about the resistance of several soybean varieties to the attacks by root-knot nematodes in Campinas. A detailed study of the nematodes involved in those experiments, which were considered as related do M. incognita, has not yet been made. One of the varieties tested, La 41-1219, proved to be resistant, thereby providing promising material for further studies and breeding. Unfortunately, such a variety when planted in Bauru, was severely attacked by a root-knot species, which is identified as M. incognita. Attacks by M. javanica bauruensis was not noted in that variety but was noted in another variety (Abura growing adjacent in the same field. The host preference of those two nematodes was specific and very marked. M. incognita attacked only var. La 41-1219 and M. javanica
Entomopathogenic nematodes are produced in two ways: in artificial media using liquid or solid fermentation methods (in vitro) or by mass producing insect hosts to be artificially exposed to mass infection by nematodes (in vivo). The yellow mealworm (Tenebrio molitor) is a good host for in vivo nema...
Dalzell, Johnathan J; McMaster, Steven; Johnston, Michael J; Kerr, Rachel; Fleming, Colin C; Maule, Aaron G
Nine non-nematode-derived double-stranded RNAs (dsRNAs), designed for use as controls in RNA interference (RNAi) screens of neuropeptide targets, were found to induce aberrant phenotypes and an unexpected inhibitory effect on motility of root knot nematode Meloidogyne incognita J2s following 24h soaks in 0.1 mg/ml dsRNA; a simple soaking procedure which we have found to elicit profound knockdown of neuronal targets in Globodera pallida J2s. We have established that this inhibitory phenomenon is both time- and concentration-dependent, as shorter 4h soaks in 0.1 mg/ml dsRNA had no negative impact on M. incognita J2 stage worms, yet a 10-fold increase in concentration to 1 mg/ml for the same 4h time period had an even greater qualitative and quantitative impact on worm phenotype and motility. Further, a 10-fold increase of J2s soaked in 0.1 mg/ml dsRNA did not significantly alter the observed phenotypic aberration, which suggests that dsRNA uptake of the soaked J2s is not saturated under these conditions. This phenomenon was not initially observed in potato cyst nematode G. pallida J2s, which displayed no aberrant phenotype, or diminution of migratory activity in response to the same 0.1 mg/ml dsRNA 24h soaks. However, a 10-fold increase in dsRNA to 1mg/ml was found to elicit comparable irregularity of phenotype and inhibition of motility in G. pallida, to that initially observed in M. incognita following a 24h soak in 0.1 mg/ml dsRNA. Again, a 10-fold increase in the number of G. pallida J2s soaked in the same volume of 1 mg/ml dsRNA preparation did not significantly affect the observed phenotypic deviation. We do not observe any global impact on transcript abundance in either M. incognita or G. pallida J2s following 0.1 mg/ml dsRNA soaks, as revealed by reverse transcriptase-PCR and quantitative PCR data. This study aims to raise awareness of a phenomenon which we observe consistently and which we believe signifies a more expansive deficiency in our knowledge and
Bohlmann, Holger; Wieczorek, Krzysztof
Plant parasitic nematodes are devastating pests on many crops. Juveniles (J2) of cyst nematodes invade the roots to induce a syncytium. This feeding site is their only source of nutrients. Male nematodes leave the roots after the fourth molt to mate with females. The females stay attached to their syncytia throughout their life and produce hundreds of eggs, which are contained in their bodies. When the females die their bodies form the cysts, which protect the eggs. Cysts can survive for many years in the soil until favorable conditions induce hatching of the juveniles. The beet cyst nematode Heterodera schachtii ( H. schachtii )is a pathogen of sugar beet ( Beta vulgaris ) but can also complete its life cycle on Arabidopsis roots growing on agar plates under sterile conditions. We present here protocols for a stock culture of H. schachtii and an infection assay on agar plates.
Full Text Available Abstract Background The complete genomes of three animals have been sequenced by global research efforts: a nematode worm (Caenorhabditis elegans, an insect (Drosophila melanogaster, and a vertebrate (Homo sapiens. Remarkably, their relationships have yet to be clarified. The confusion concerns the enigmatic position of nematodes. Traditionally, nematodes have occupied a basal position, in part because they lack a true body cavity. However, the leading hypothesis now joins nematodes with arthropods in a molting clade, Ecdysozoa, based on data from several genes. Results We tested the Ecdysozoa hypothesis with analyses of more than 100 nuclear protein alignments, under conditions that would expose biases, and found that it was not supported. Instead, we found significant support for the traditional hypothesis, Coelomata. Our result is robust to different rates of sequence change among genes and lineages, different numbers of taxa, and different species of nematodes. Conclusion We conclude that insects (arthropods are genetically and evolutionarily closer to humans than to nematode worms.
de la Torre, Mayra
Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.
Meyer, Susan L F; Halbrendt, John M; Carta, Lynn K; Skantar, Andrea M; Liu, Ting; Abdelnabby, Hazem M E; Vinyard, Bryan T
The antibiotic 2,4-diacetylphloroglucinol (DAPG) is produced by some isolates of the beneficial bacterium Pseudomonas fluorescens. DAPG is toxic to many organisms, and crop yield increases have been reported after application of DAPG-producing P. fluorescens. This study was conducted to determine whether DAPG is toxic to selected nematodes. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita, Pratylenchus scribneri and Xiphinema americanum, and the bacterial-feeding nematodes Caenorhabditis elegans, Pristionchus pacificus, and Rhabditis rainai, were immersed in concentrations ranging from 0 to 100 μg/ml DAPG. Egg hatch and viability of juveniles and adults were determined. DAPG was toxic to X. americanum adults, with an LD₅₀ of 8.3 μg/ml DAPG. DAPG decreased M. incognita egg hatch, but stimulated C. elegans hatch during the first hours of incubation. Viability of M. incognita J2 and of C. elegans J1 and adults was not affected. There were no observed effects on the other nematodes. The study indicated that DAPG is not toxic to all nematodes, and did not affect the tested species of beneficial bacterial-feeding nematodes. Augmentation of DAPG-producing P. fluorescens populations for nematode biocontrol could be targeted to specific nematode species known to be affected by this compound and by other antibiotics produced by the bacteria, or these bacteria could be used for other possible effects, such as induced plant resistance.
Lilley, Catherine J; Atkinson, Howard J; Urwin, Peter E
SUMMARY Taxonomy: Superkingdom Eukaryota; kingdom Metazoa; phylum Nematoda; class Chromadorea; order Tylenchida; suborder Tylenchina; superfamily Tylenchoidea; family Heteroderidae; subfamily Heteroderinae; main genera Heterodera and Globodera. Cyst nematodes comprise approximately 100 known species in six genera. They are pathogens of temperate, subtropical and tropical plant species and the host range of many species is narrow. The most economically important species are within the Globodera and Heterodera genera. Globodera pallida and G. rostochiensis are important pathogens of potato crops. There are many economic species in the Heterodera genus, including Heterodera glycines (soybean cyst nematode), H. avenae (cereal cyst nematode) and H. schachtii (sugar beet cyst nematode), the last of which attacks a range of Chenopodiaceae and Cruciferae, including Arabidopsis thaliana. Disease symptoms: Field symptoms of severe cyst nematode infection are often stunting, wilting and chlorosis, but considerable yield loss can occur without obvious symptoms. The only unique indicator of cyst nematode infection is the presence of adult female nematodes attached to host roots after several weeks of parasitism. Disease control: This is usually achieved by using integrated pest management involving cultural practices such as crop rotation, resistant cultivars if available and chemical control when economically justified.
Johnathan J Dalzell
Full Text Available While RNA interference (RNAi has been deployed to facilitate gene function studies in diverse helminths, parasitic nematodes appear variably susceptible. To test if this is due to inter-species differences in RNAi effector complements, we performed a primary sequence similarity survey for orthologs of 77 Caenorhabditis elegans RNAi pathway proteins in 13 nematode species for which genomic or transcriptomic datasets were available, with all outputs subjected to domain-structure verification. Our dataset spanned transcriptomes of Ancylostoma caninum and Oesophagostomum dentatum, and genomes of Trichinella spiralis, Ascaris suum, Brugia malayi, Haemonchus contortus, Meloidogyne hapla, Meloidogyne incognita and Pristionchus pacificus, as well as the Caenorhabditis species C. brenneri, C. briggsae, C. japonica and C. remanei, and revealed that: (i Most of the C. elegans proteins responsible for uptake and spread of exogenously applied double stranded (dsRNA are absent from parasitic species, including RNAi-competent plant-nematodes; (ii The Argonautes (AGOs responsible for gene expression regulation in C. elegans are broadly conserved, unlike those recruited during the induction of RNAi by exogenous dsRNA; (iii Secondary Argonautes (SAGOs are poorly conserved, and the nuclear AGO NRDE-3 was not identified in any parasite; (iv All five Caenorhabditis spp. possess an expanded RNAi effector repertoire relative to the parasitic nematodes, consistent with the propensity for gene loss in nematode parasites; (v In spite of the quantitative differences in RNAi effector complements across nematode species, all displayed qualitatively similar coverage of functional protein groups. In summary, we could not identify RNAi effector deficiencies that associate with reduced susceptibility in parasitic nematodes. Indeed, similarities in the RNAi effector complements of RNAi refractory and competent nematode parasites support the broad applicability of this research
Mota, Manuel; Vieira, Paulo
According to the European Plant Protection Organization, the pinewood nematode (PWN), Bursaphelenchus xylophilus is a quarantine organism at the top of the list of the pathogenic species. PWN may be found in North America (Canada, USA and Mexico) and in East Asia (Japan, Korea, China and Taiwan) and has a highly destructive capability towards conifers, in a relatively short time, causing serious economic damage in Japan, China and Korea. This nematode surveying is extremely imp...
Hiltpold, Ivan; Jaffuel, Geoffrey; Turlings, Ted C J
To defend themselves against herbivores and pathogens, plants produce numerous secondary metabolites, either constitutively or de novo in response to attacks. An intriguing constitutive example is the exudate produced by certain root-cap cells that can induce a state of reversible quiescence in plant-parasitic nematodes, thereby providing protection against these antagonists. The effect of such root exudates on beneficial entomopathogenic nematodes (EPNs) remains unclear, but could potentially impair their use in pest management programmes. We therefore tested how the exudates secreted by green pea (Pisum sativum) root caps affect four commercial EPN species. The exudates induced reversible quiescence in all EPN species tested. Quiescence levels varied with the green pea cultivars tested. Notably, after storage in root exudate, EPN performance traits were maintained over time, whereas performances of EPNs stored in water rapidly declined. In sharp contrast to high concentrations, lower concentrations of the exudate resulted in a significant increase in EPN activity and infectiousness, but still reduced the activity of two plant-parasitic nematode species. Our study suggests a finely tuned dual bioactivity of the exudate from green pea root caps. Appropriately formulated, it can favour long-term storage of EPNs and boost their infectiousness, while it may also be used to protect plants from plant-parasitic nematodes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema kill arthropods with the aid of their bacterial symbionts. These nematodes are potent microbial control agents that have been widely commercialized for control of economically important insect pests. Biocontrol efficacy relies...
Hawaii’s diverse and mild climate allows for the cultivation of many crops. The introduction of each crop plant brought along its associated nematode pests. These plant-parasitic nematodes became established and are now endemic to the islands. Plantation agriculture determined the major nematode ...
Samish, M; Glazer, I
Entomopathogenic steinemematid and heterorhabditid nematodes are increasingly used to control insect pests of economically important crops. Laboratory and field simulation trials show that ticks are also susceptible to these nematodes. The authors review the potential of entomogenous nematodes for the control of ticks.
Ritzinger, C H; McSorley, R; Gallaher, R N
The effects of perennial peanut (Arachis glabrata) hay, an aged yard-waste compost (mainly woodchips), and a control treatment without amendment were determined on two population levels of root-knot (Melaidogyne arenaria) nematode over three consecutive years in field microplots. Okra (Hibiscus esculentus, susceptible to the root-knot nematode) and a rye (Secale cereale) cover crop (poor nematode host) were used in the summer and winter seasons, respectively. The organic amendment treatments affected plant growth parameters. In the first year, okra yields were greatest in peanut-amended plots. Yield differences with amendment treatment diminished in the second and third years. Okra plant height, total fruit weight, and fruit number were greater with the lower population level of the root-knot nematode. Residual levels of nutrients in soil were greater where root-knot nematode levels and damage were higher and plant growth was poor. Nutrient levels affected the growth of a subsequent rye cover crop.
Ehlers, R U
In Europe total revenues in the biocontrol market have reached approximately 200 million Euros. The sector with the highest turn-over is the market for beneficial invertebrates with a 55% share, followed by microbial agents with approximately 25%. Annual growth rates of up to 20% have been estimated. Besides microbial plant protection products that are currently in the process of re-registration, several microbial products have been registered or are in the process of registration, following the EU directive 91/414. Entomopathogenic nematodes (EPN) are exceptionally safe biocontrol agents. Until today, they are exempted from registration in most European countries, the reason why SMEs were able to offer economically reasonable nematode-based products. The development of technology for mass production in liquid media significantly reduced the product costs and accelerated the introduction of nematode products in tree nurseries, ornamentals, strawberries, mushrooms, citrus and turf. Progress in storage and formulation technology has resulted in high quality products which are more resistant to environmental extremes occurring during transportation to the user. The cooperation between science, industry and extension within the EU COST Action 819 has supported the development of quality control methods. Today four companies produce EPN in liquid culture, offering 8 different nematode species. Problems with soil insects are increasing. Grubs, like Melolontha melolontha and other scarabaeidae cause damage in orchards and turf. Since the introduction of the Western Corn Rootworm Diabrotica virgifera into Serbia in 1992, this pests as spread all over the Balkan Region and has reached Italy, France and Austria. These soil insect pests are potential targets for EPN. The development of insecticide resistance has opened another sector for EPN. Novel adjuvants used to improve formulation of EPN have enabled the foliar application against Western Flower Thrips and Plutella
Xenorhabdus spp bacteria are associated with Steinernematid nematodes and produce antifungal metabolites that protect nematode-infected cadavers from fungal colonization. Previous work demonstrated concentrated or cell-free metabolites of X. szentirmaii were toxic to fungal phytopathogens. We prepar...
Vidal-Diez de Ulzurrun, Guillermo; Hsueh, Yen-Ping
Nematode-trapping fungi develop complex trapping devices to capture and consume nematodes. The dynamics of these organisms is especially important given the pathogenicity of nematodes and, consequently, the potential application of nematode-trapping fungi as biocontrol agents. Furthermore, both the nematodes and nematode-trapping fungi can be easily grown in laboratories, making them a unique manipulatable predator-prey system to study their coevolution. Several different aspects of these fungi have been studied, such as their genetics and the different factors triggering trap formation. In this review, we use the nematode-trapping fungus Arthrobotrys oligospora (which forms adhesive nets) as a model to describe the trapping process. We divide this process into several stages; namely attraction, recognition, trap formation, adhesion, penetration, and digestion. We summarize the latest findings in the field and current knowledge on the interactions between nematodes and nematode-trapping fungi, representing both sides of the predator-prey interaction.
Reniform nematodes (Rotylenchulus reniformis) from pot culture were attached with in vitro produced Pasteuria spp. spores using a centrifuge attachment technique that resulted in 40-50% of the vermiform nematodes with spores adhering to their cuticles. Attached nematodes were placed into small plast...
Rengarajan, Sophie; Hallem, Elissa A
Over one billion people worldwide are infected with parasitic nematodes. Many parasitic nematodes actively search for hosts to infect using volatile chemical cues, so understanding the olfactory signals that drive host seeking may elucidate new pathways for preventing infections. The free-living nematode Caenorhabditis elegans is a powerful model for parasitic nematodes: because sensory neuroanatomy is conserved across nematode species, an understanding of the microcircuits that mediate olfaction in C. elegans may inform studies of olfaction in parasitic nematodes. Here we review circuit mechanisms that allow C. elegans to respond to odorants, gases, and pheromones. We also highlight work on the olfactory behaviors of parasitic nematodes that lays the groundwork for future studies of their olfactory microcircuits. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Sorobetea, D.; Svensson Frej, M.; Grencis, R.
Numerous species of nematodes have evolved to inhabit the gastrointestinal tract of animals and humans, with over a billion of the world's population infected with at least one species. These large multicellular pathogens present a considerable and complex challenge to the host immune system give...
Jacqueline B. Matthews
Full Text Available Anthelmintics have been applied indiscriminately to control horse nematodes for over 40 years. Three broad-spectrum anthelmintic classes are currently registered for nematode control in horses: benzimidazoles (fenbendazole, oxibendazole, tetrahydropyrimidines (pyrantel and macrocyclic lactones (ivermectin, moxidectin. Generally, control strategies have focused on nematode egg suppression regimens that involve the frequent application of anthelmintics to all horses at intervals based on strongyle egg reappearance periods after treatment. The widespread use of such programmes has substantially reduced clinical disease, especially that associated with large strongyle species; however, high treatment frequency has led to considerable selection pressure for anthelmintic resistance, particularly in cyathostomin species. Field studies published over the last decade indicate that benzimidazole resistance is widespread globally in cyathostomins and there are also many reports of resistance to pyrantel in these worms. Cyathostomin resistance to macrocyclic lactone compounds is emerging, principally measured as a reduction in strongyle egg reappearance time observed after treatment. Ivermectin resistance is a further concern in the small intestinal nematode, Parascaris equorum, an important pathogen of foals. These issues indicate that horse nematodes must now be controlled using methods less dependent on anthelmintic use and more reliant on management practices designed to reduce the force of infection in the environment. Such strategies include improved grazing management integrated with targeted anthelmintic administration involving faecal egg count (FEC-directed treatments. The latter require that the supporting diagnostic tests available are robust and practically applicable. Recent research has focused on maximising the value of FEC analysis in horses and on optimizing protocols for anthelmintic efficacy testing. Other studies have sought to develop
Viglierchio, D. R.
Of 12 stylet-bearing nematodes used for inoculations, Pratylenchus penetrans, P. brachyurus, P. vulnus, Ditylenchus destructor, Meloidogyne incognita, M. javanica, and M. hapla reproduced on Pinus ponderosa, while Xiphinema index, Aphelenchus avenae, Paratylenehus neoamblycephalus, Tylenchulus semipenetrans, and Macroposthonia xenoplax did not. P. vulnus, P. brachyurus, P. penetrans, A. avenae, D. destructor, T. semipenetrans, and P. neoamblycephalus significantly suppressed both the shoot and root wet weights of ponderosa pine seedlings obtained from stands in five different locations. X. index significantly suppressed root wet weights, M. xenoplax siguificantly suppressed shoot wet weight, and M. incognita, M. javanica, and M. hapla suppressed neither at the inoculation levels used. Injurious nematodes tended to suppress root growth more than shoot growth. Seedlings from two locations produced greater shoot growth wet weight than did seedlings from the other three locations. The more injurious nematodes tended to cause an increase in the water content of shoots. Frequency analyses of seedling population shoot-root ratios indicated that ponderosa pine seedlings could be selected for better shoot-root ratios as well as for resistance to several pathogenic nematodes. PMID:19300659
Quist, Casper W; Smant, Geert; Helder, Johannes
Within the species-rich and trophically diverse phylum Nematoda, at least four independent major lineages of plant parasites have evolved, and in at least one of these major lineages plant parasitism arose independently multiple times. Ribosomal DNA data, sequence information from nematode-produced, plant cell wall-modifying enzymes, and the morphology and origin of the style(t), a protrusible piercing device used to penetrate the plant cell wall, all suggest that facultative and obligate plant parasites originate from fungivorous ancestors. Data on the nature and diversification of plant cell wall-modifying enzymes point at multiple horizontal gene transfer events from soil bacteria to bacterivorous nematodes resulting in several distinct lineages of fungal or oomycete-feeding nematodes. Ribosomal DNA frameworks with sequence data from more than 2,700 nematode taxa combined with detailed morphological information allow for explicit hypotheses on the origin of agronomically important plant parasites, such as root-knot, cyst, and lesion nematodes.
Pomegranate (Punica granatum) fruit and roselle (Hibiscus sabdariffa) leaves have been used in traditional medicine, including as anthelmintics. Methanolic extracts from these plants were investigated for activity against the southern root-knot nematode (RKN) Meloidogyne incognita. Dried, ground p...
DR. NJ TONUKARI
Feb 16, 2012 ... the protoplasts could be regenerated on potato dextrose agar (PDA), RA and IM regeneration media. D. cionopaga ... mechanisms of nematode infection by nematophagous fungi. Serine ...... Susceptibility of root-knot and cyst.
fixing capacity. A field study was conducted in 1999 and 2000 at Ejura in the forest savanna transition ..... plants. Soybean, cowpea, and groundnut could be susceptible to various root knot nematode ..... Maize and legumes production guide.
friendly management of root-knot nematodes, Meloidogyne incognita on tomato. Abstract PDF · Vol 4, No 3 (2015) - Articles Evaluation of different strains of eri silkworms (Samia cynthia ricini B.) for their adaptability and silk yield in Ethiopia
Three species of fungi, Catenaria auxiliarls (Kühn) Tribe, Nematophthora gynophila Kerry and Crump, and a Lagenidiaceous fungus have been found attacking female cyst nematodes. All are zoosporic fungi which parasitize females on the root surface, cause the breakdown of the nematode cuticle, and prevent cyst formation. Their identification and some aspects of their biology are reviewed. N. gynophila is widespread in Britain and reduces populations of the cereal cyst nematode, Heterodera avenae...
Qamar, M.F.; Butt, K.; Qureshi, N.A.
Three hundred fresh water fishes of six species were collected from six different fish farms of Lahore for the prevalence of nematodes. Out of 300 fishes examined, 12 were found to be infected with the helminthes, majority of them were isolated from the stomach and intestines. The following two species of nematodes were recorded; Capillaria spp. and Eustrongylides spp. The overall prevalence of intestinal nematodes was recorded as 4%(12/300). The prevalence of nematodes was recorded on monthly basis which ranged from 0-8%. The highest prevalence of nematodes was 8% (4/50) during March, while the lowest prevalence was noted in June 0%.Singharee (Sperata sawari) showed the maximum infestation of nematodes of 8% (4/50), whereas in Silver Carp (Hypopthaimichthys molitrix) minimum prevalence of nematode (0%) was noted. The prevalence of different nematode in a particular fish specie was also recorded, and it was stated that overall prevalence of capillaria spp. was 6% in Rahu (Labeo rohita) and Saul (Channa marullius). Similarly overall infestation of Eustrongylides sp. was recorded as 4% in Singharee (Sperata sawari) and Silver carp (Hypopthaimichthys molitrix). The nematode intensity might be linked with the genetic makeup, intestinal vigor, and other managemental and environmental factors. (author)
Groundnut is the common name for several leguminous plant species producing seed that mature underground, including Bambara groundnut (Vigna subterranean), Hausa groundnut (Macrotyloma geocarpum), and peanut (Arachis spp.). Hausa groundnut is cultivated as a food crop primarily in West Africa and t...
Ja Yeong Jang
Full Text Available Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS. Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10% and oxalic acid-WP8 (ai 8%, were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate. These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.
Full Text Available The pathogenicity, development and reproduction of Steinernema sp., isolate Skpr-20/Str, were studied using Tenebrio molitor. Results revealed that pathogenicity, development and reproduction were significantly influenced by nematode doses. Although the number of invading IJs increased with increasing dose, percentage penetration declined. The IJs reached adulthood within 3 days. Females laid eggs from day 4-7. All eggs remaining inside uterus develop inside the maternal body. The first female bearing endotokia matricida was observed on day 5. In a sand-based assay, nematode was more pathogenic at lower dose instead of higher ones, where optimum dose was 80 nematodes per larva and average number of progeny per female was 5438. Under crowded conditions, development proceeds to IJ stage instead of the J3. The average length and width decreased with increasing of nematode doses. The IJ produced in cadavers infested with 640 nematodes per larva was significantly smaller (492 ± 6.4 µm than offspring from other doses. The number of days which nematodes first emerged from the cadavers decreased with increasing dose. IJ first emerged at the average of 10-13 days at high IJ densities. It is concluded that the wide experimental characteristic of EPNs is also true for Steinernema sp., isolate Skpr-20/Str.
Kim, Shin Woong; Moon, Jongmin; An, Youn-Joo
The success of soil toxicity tests using Caenorhabditis elegans may depend in large part on recovering the organisms from the soil. However, it can be difficult to learn the International Organization for Standardization/ASTM International recovery process that uses the colloidal silica flotation method. The present study determined that a soil-agar isolation method provides a highly efficient and less technically demanding alternative to the colloidal silica flotation method. Test soil containing C. elegans was arranged on an agar plate in a donut shape, a linear shape, or a C curve; and microbial food was placed outside the soil to encourage the nematodes to leave the soil. The effects of ventilation and the presence of food on nematode recovery were tested to determine the optimal conditions for recovery. A linear arrangement of soil on an agar plate that was sprinkled with microbial food produced nearly 83% and 90% recovery of live nematodes over a 3-h and a 24-h period, respectively, without subjecting the nematodes to chemical stress. The method was tested using copper (II) chloride dihydrate, and the resulting recovery rate was comparable to that obtained using colloidal silica flotation. The soil-agar isolation method portrayed in the present study enables live nematodes to be isolated with minimal additional physicochemical stress, making it a valuable option for use in subsequent sublethal tests where live nematodes are required. © 2014 SETAC.
Full Text Available Phytoparasitic nematodes that are able to infect and reproduce on plants that are considered resistant are referred to as virulent. The mechanism(s that virulent nematodes employ to evade or suppress host plant defenses are not well understood. Here we report the use of a genetic strategy (allelic imbalance analysis to associate single nucleotide polymorphisms (SNPs with nematode virulence genes in Heterodera glycines, the soybean cyst nematode (SCN. To accomplish this analysis, a custom SCN SNP array was developed and used to genotype SCN F3-derived populations grown on resistant and susceptible soybean plants. Three SNPs reproducibly showed allele imbalances between nematodes grown on resistant and susceptible plants. Two candidate SCN virulence genes that were tightly linked to the SNPs were identified. One SCN gene encoded biotin synthase (HgBioB, and the other encoded a bacterial-like protein containing a putative SNARE domain (HgSLP-1. The two genes mapped to two different linkage groups. HgBioB contained sequence polymorphisms between avirulent and virulent nematodes. However, the gene encoding HgSLP-1 had reduced copy number in virulent nematode populations and appears to produce multiple forms of the protein via intron retention and alternative splicing. We show that HgSLP-1 is an esophageal-gland protein that is secreted by the nematode during plant parasitism. Furthermore, in bacterial co-expression experiments, HgSLP-1 co-purified with the SCN resistance protein Rhg1 α-SNAP, suggesting that these two proteins physically interact. Collectively our data suggest that multiple SCN genes are involved in SCN virulence, and that HgSLP-1 may function as an avirulence protein and when absent it helps SCN evade host defenses.
Gang, Spencer S; Hallem, Elissa A
The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect more than one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries . Parasitic nematodes of livestock and crops result in billions of dollars in losses each year . Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration . Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.
May 31, 2016 ... The relationship between cost and benefit of the nematicide applications was also estimated. ... based on nematode threshold (100 nematodes per g of fresh root) which resulted in two applications; ..... France. Araya M, 2004. Situación actual del manejo de nematodos en banano (Musa AAA) y plátano.
Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr El-Sheikh Governorate, Egypt, ...
Weinstein, Sara B.; Lafferty, Kevin D.
Human actions can affect wildlife and their nematode parasites. Species introductions and human-facilitated range expansions can create new host–parasite interactions. Novel hosts can introduce parasites and have the potential to both amplify and dilute nematode transmission. Furthermore, humans can alter existing nematode dynamics by changing host densities and the abiotic conditions that affect larval parasite survival. Human impacts on wildlife might impair parasites by reducing the abundance of their hosts; however, domestic animal production and complex life cycles can maintain transmission even when wildlife becomes rare. Although wildlife nematodes have many possible responses to human actions, understanding host and parasite natural history, and the mechanisms behind the changing disease dynamics might improve disease control in the few cases where nematode parasitism impacts wildlife.
Siddique, Shahid; Radakovic, Zoran S; De La Torre, Carola M; Chronis, Demosthenis; Novák, Ondřej; Ramireddy, Eswarayya; Holbein, Julia; Matera, Christiane; Hütten, Marion; Gutbrod, Philipp; Anjam, Muhammad Shahzad; Rozanska, Elzbieta; Habash, Samer; Elashry, Abdelnaser; Sobczak, Miroslaw; Kakimoto, Tatsuo; Strnad, Miroslav; Schmülling, Thomas; Mitchum, Melissa G; Grundler, Florian M W
Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction.
Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo
Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.
Camilla Martins de Oliveira
Full Text Available ABSTRACT: Soybean is a commodity of great economic importance worldwide, particularly in Brazil, world’s second largest producer. Nematodes, especially those of the Meloidogyne genus, severely limit productivity. Identification of nematode species is important for effective soybean management. Here, 26 populations of root-knot nematode (Meloidogyne spp. from 15 municipalities in the states of Bahia, Mato Grosso, Goias, and Minas Gerais were characterized based on the morphology of the female perineal region, esterase profile, and identification based on amplification of specific regions of the population genome. Among the Meloidogyne spp. populations obtained, M. incognita and M. javanica, were identified. No mixed populations were present in the samples. Diagnosis based on molecular analysis was shown to be reliable and the fastest for characterization of nematode populations compared to other methods analyzed.
Full Text Available The research on “Biological control of plant parasitic nematodes by nematophagous bacteria (Pasteuria penetrans” was planned to be conducted within 3 years period, started in 1994/1995. In the first year research was done with the following objectives: 1 inventory on the isolates of P. penetrans, and 2 study on the mass production and pathogenicity test of P. penetrans. Survey of P. penetrans was done in the provinces of D.I. Yogyakarta, Central Java, East Java, and West Java. Soil and root samples were collected in this survey, plant parasitic nematodes were isolated using centrifugation and funnel and spray method. Mass production of P. penetrans was done with their host especially root-knot nematodes (Meloidogyne spp.. The bacterial infected nematodes were inoculated on tomato planted on sterilized soil. Roots contain root-knot nematodes inhabiting spores of P. penetrans were used as inoculum source. The pathogenicity tests of the isolates were done using bioassay method and in the green house in Completely Randomized Design. The research results is as follows: 1 seventeesn isolates of P. penetrans were found in the survey, these isolates were pathogenic to root-knot nematodes, 2 mass production of P. penetrans was done with their host especially root-knot nematodes and 4 treatment with P. penetrans significantly reduced the root-gall caused by root-knot nematodes. Key words: biological control, parasitic nematodes, Pasteuria penetrans
Heininger, Peter; Hoess, Sebastian; Claus, Evelyn; Pelzer, Juergen; Traunspurger, Walter
Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure. - Nematode community structure of river sediments is related to pollution and site structure
Heininger, Peter [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Hoess, Sebastian [Ecossa - Ecological Sediment and Soil Assessment, Thierschstr. 43, 80538 Munich (Germany); Claus, Evelyn [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Pelzer, Juergen [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Traunspurger, Walter [University of Bielefeld, Department of Animal Ecology, Morgenbreede 45, 33615 Bielefeld (Germany)]. E-mail: firstname.lastname@example.org
Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure. - Nematode community structure of river sediments is related to pollution and site structure.
Full Text Available At least 13 species of intestinal nematodes and 4 species of blood and tissue nematodes have been reported infecting man in Indonesia. Five species of intestinal nematodes are very common and highly prevalent, especially in the rural areas and slums of the big cities. Those species are Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Trichuris trichiura and Oxyuris vermicularis, while Strongyloides stercoralis is disappearing. The prevalence of the soil transmitted helminths differs from place to place, depending on many factors such as the type of soil, human behaviour etc. Three species of lymph dwelling filarial worms are known to be endemic, the urban Wuchereria bancrofti is low endemic in Jakarta and a few other cities along the north coast of Java, with Culex incriminated as vector, high endemicity is found in Irian Jaya, where Anopheline mosquitoes act as vectors. Brugia malayi is widely distributed and is still highly endemic in many areas. The zoonotic type is mainly endemic in swampy areas, and has many species of Mansonia mosquitoes as vectors. B.timori so far has been found only in the south eastern part of the archipelago and has Anopheles barbirostris as vector. Human infections with animal parasites have been diagnosed properly only when adult stages were found either in autopsies or removed tissues. Cases of infections with A. caninum, A.braziliense, A.ceylanicum, Trichostrongylus colubriformis, T.axei and Oesophagostomum apiostomum have been desribed from autopsies, while infections with Gnathostoma spiningerum have been reported from removed tissues. Infections with the larval stages such as VLM, eosinophylic meningitis, occult filanasis and other could only be suspected, since the diagnosis was extremely difficult and based on the finding and identification of the parasite. Many cases of creeping eruption which might be caused by the larval stages of A.caninum and A.braziliense and Strongyloides stercoralis
Joao Carlos dos Reis Cardoso
Full Text Available In vertebrates, receptors of the rhodopsin G-protein coupled superfamily (GPCRs play an important role in the regulation of feeding and energy homeostasis and are activated by peptide hormones produced in the brain-gut axis. These peptides regulate appetite and energy expenditure by promoting or inhibiting food intake. Sequence and function homologues of human GPCRs involved in feeding exist in the nematode roundworm, Caenorhabditis elegans (C. elegans and the arthropod fruit fly, Drosophila melanogaster (D. melanogaster, suggesting that the mechanisms that regulate food intake emerged early and have been conserved during metazoan radiation. Nematodes and arthropods are the most diverse and successful animal phyla on Earth. They can survive in a vast diversity of environments and have acquired distinct life styles and feeding strategies. The aim of the present review is to investigate if this diversity has affected the evolution of invertebrate GPCRs. Homologues of the C. elegans and D. melanogaster rhodopsin receptors were characterized in the genome of other nematodes and arthropods and receptor evolution compared. With the exception of bombesin receptors (BBR that are absent from nematodes, a similar gene complement was found. In arthropods, rhodopsin GPCR evolution is characterized by species-specific gene duplications and deletions and in nematodes by gene expansions in species with a free-living stage and gene deletions in representatives of obligate parasitic taxa. Based upon variation in GPCR gene number and potentially divergent functions within phyla we hypothesize that life style and feeding diversity practiced by nematodes and arthropods was one factor that contributed to rhodopsin GPCR gene evolution. Understanding how the regulation of food intake has evolved in invertebrates will contribute to the development of novel drugs to control nematodes and arthropods and the pests and diseases that use them as vectors.
Cardoso, João C R; Félix, Rute C; Fonseca, Vera G; Power, Deborah M
In vertebrates, receptors of the rhodopsin G-protein coupled superfamily (GPCRs) play an important role in the regulation of feeding and energy homeostasis and are activated by peptide hormones produced in the brain-gut axis. These peptides regulate appetite and energy expenditure by promoting or inhibiting food intake. Sequence and function homologs of human GPCRs involved in feeding exist in the nematode roundworm, Caenorhabditis elegans (C. elegans), and the arthropod fruit fly, Drosophila melanogaster (D. melanogaster), suggesting that the mechanisms that regulate food intake emerged early and have been conserved during metazoan radiation. Nematodes and arthropods are the most diverse and successful animal phyla on Earth. They can survive in a vast diversity of environments and have acquired distinct life styles and feeding strategies. The aim of the present review is to investigate if this diversity has affected the evolution of invertebrate GPCRs. Homologs of the C. elegans and D. melanogaster rhodopsin receptors were characterized in the genome of other nematodes and arthropods and receptor evolution compared. With the exception of bombesin receptors (BBR) that are absent from nematodes, a similar gene complement was found. In arthropods, rhodopsin GPCR evolution is characterized by species-specific gene duplications and deletions and in nematodes by gene expansions in species with a free-living stage and gene deletions in representatives of obligate parasitic taxa. Based upon variation in GPCR gene number and potentially divergent functions within phyla we hypothesize that life style and feeding diversity practiced by nematodes and arthropods was one factor that contributed to rhodopsin GPCR gene evolution. Understanding how the regulation of food intake has evolved in invertebrates will contribute to the development of novel drugs to control nematodes and arthropods and the pests and diseases that use them as vectors.
Jasmer, D.P.; Goverse, A.; Smant, G.
Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent
Kikuchi, Taisei; Eves-van den Akker, Sebastian; Jones, John T
Plant parasitism has evolved independently on at least four separate occasions in the phylum Nematoda. The application of next-generation sequencing (NGS) to plant-parasitic nematodes has allowed a wide range of genome- or transcriptome-level comparisons, and these have identified genome adaptations that enable parasitism of plants. Current genome data suggest that horizontal gene transfer, gene family expansions, evolution of new genes that mediate interactions with the host, and parasitism-specific gene regulation are important adaptations that allow nematodes to parasitize plants. Sequencing of a larger number of nematode genomes, including plant parasites that show different modes of parasitism or that have evolved in currently unsampled clades, and using free-living taxa as comparators would allow more detailed analysis and a better understanding of the organization of key genes within the genomes. This would facilitate a more complete understanding of the way in which parasitism has shaped the genomes of plant-parasitic nematodes.
Howe, Kevin; Davis, Paul; Paulini, Michael; Tuli, Mary Ann; Williams, Gary; Yook, Karen; Durbin, Richard; Kersey, Paul; Sternberg, Paul W
WormBase (www.wormbase.org) has been serving the scientific community for over 11 years as the central repository for genomic and genetic information for the soil nematode Caenorhabditis elegans. The resource has evolved from its beginnings as a database housing the genomic sequence and genetic and physical maps of a single species, and now represents the breadth and diversity of nematode research, currently serving genome sequence and annotation for around 20 nematodes. In this article, we focus on WormBase's role of genome sequence annotation, describing how we annotate and integrate data from a growing collection of nematode species and strains. We also review our approaches to sequence curation, and discuss the impact on annotation quality of large functional genomics projects such as modENCODE.
Full Text Available Free-living soil nematodes have successfully adapted world-wide to nearly all soil types from the highest to the lowest of elevations. In the current study, nematodes were isolated from soil samples and fungi associated with these free-living soil nematodes were determined. Large subunit (LSU rDNAs of nematode-associated fungi were amplified and sequenced to construct phylogenetic trees. Nematode-associated fungi were observed in six nematode strains belonging to Acrobeloides, Steinernema and Cephalobus genera in different habitats. Malassezia and Cladosporium fungal strains indicated an association with Acrobeloides and Cephalobus nematodes, while Alternaria strains demonstrated an association with the Steinernema strain. Interactions between fungi and free-living nematodes in soil are discussed. We suggest that nematodes act as vectors for fungi.
Wang, Bai-Le; Chen, Yong-Hong; He, Jia-Ning; Xue, Hua-Xi; Yan, Ni; Zeng, Zhi-Jun; Bennett, Joan W; Zhang, Ke-Qin; Niu, Xue-Mei
The adjustment of metabolic patterns is fundamental to fungal biology and plays vital roles in adaptation to diverse ecological challenges. Nematode-trapping fungi can switch their lifestyle from saprophytic to pathogenic by developing specific trapping devices induced by nematodes to infect their prey as a response to nutrient depletion in nature. However, the chemical identity of the specific fungal metabolites used during the switch remains poorly understood. We hypothesized that these important signal molecules might be volatile in nature. Gas chromatography-mass spectrometry was used to carry out comparative analysis of fungal metabolomics during the saprophytic and pathogenic lifestyles of the model species Arthrobotrys oligospora Two media commonly used in research on this species, cornmeal agar (CMA) and potato dextrose agar (PDA), were chosen for use in this study. The fungus produced a small group of volatile furanone and pyrone metabolites that were associated with the switch from the saprophytic to the pathogenic stage. A. oligospora fungi grown on CMA tended to produce more traps and employ attractive furanones to improve the utilization of traps, while fungi grown on PDA developed fewer traps and used nematode-toxic furanone metabolites to compensate for insufficient traps. Another volatile pyrone metabolite, maltol, was identified as a morphological regulator for enhancing trap formation. Deletion of the gene AOL_s00079g496 in A. oligospora led to increased amounts of the furanone attractant (2-fold) in mutants and enhanced the attractive activity (1.5-fold) of the fungus, while it resulted in decreased trap formation. This investigation provides new insights regarding the comprehensive tactics of fungal adaptation to environmental stress, integrating both morphological and metabolomic mechanisms. IMPORTANCE Nematode-trapping fungi are a unique group of soil-living fungi that can switch from the saprophytic to the pathogenic lifestyle once they come
Conservation biological control is the modification of the environment or existing practices to protect and enhance antagonistic organisms to reduce damage from pests. This approach to biological control has received insufficient attention compared with inundative applications of microbial antagonists to control nematodes. This review provides examples of how production practices can enhance or diminish biological control of plant-parasitic nematodes and other soilborne pests. Antagonists of nematodes can be enhanced by providing supplementary food sources such as occurs when organic amendments are applied to soil. However, some organic amendments (e.g., manures and plants containing allelopathic compounds) can also be detrimental to nematode antagonists. Plant species and genotype can strongly influence the outcome of biological control. For instance, the susceptibility of the plant to the nematode can determine the effectiveness of control; good hosts will require greater levels of suppression than poor hosts. Plant genotype can also influence the degree of rhizosphere colonization and antibiotic production by antagonists, as well the expression of induced resistance by plants. Production practices such as crop rotation, fallow periods, tillage, and pesticide applications can directly disrupt populations of antagonistic organisms. These practices can also indirectly affect antagonists by reducing their primary nematode host. One of the challenges of conservation biological control is that practices intended to protect or enhance suppression of nematodes may not be effective in all field sites because they are dependent on indigenous antagonists. Ultimately, indicators will need to be identified, such as the presence of particular antagonists, which can guide decisions on where it is practical to use conservation biological control. Antagonists can also be applied to field sites in conjunction with conservation practices to improve the consistency, efficacy, and
Full Text Available In this paper, we concentrate on a comparison of plant and animal-parasitic nematodes, to gain insight into the factors that influence the acquisition of the drug resistance by nematodes. Comparing nematode parasite of domestic animals and cultivated plants, it appears that drug resistance threatens only domestic animal production. Does the paucity of report on nematicide field resistance reflect reality or, is nematicide resistance bypassed by other management practices, specific to cultivated plants (i.e. agricultural control ? First, it seems that selection pressure by treatments in plants is not as efficient as selection pressure in ruminants. Agronomic practices (i.e. sanitation, early planting, usage of nematodes resistant cultivar and crop rotation are frequently used to control parasitic-plant nematodes. Although the efficiency of such measures is generally moderate to high, integrated approaches are developing successfully in parasitic-plant nematode models. Secondly, the majority of anthelmintic resistance cases recorded in animal-parasitic nematodes concern drug families that are not used in plant-parasitic nematodes control (i.e. benzimidazoles, avermectines and levamisole. Thirdly, particular life traits of parasitic-plant nematodes (low to moderate fecundity and reproductive strategy are expected to reduce probability of appearance and transmission of drug resistance genes. It has been demonstrated that, for a large number of nematodes such as Meloidogyne spp., the mode of reproduction by mitotic parthenogenesis reduced genetic diversity of populations which may prevent a rapid drug resistance development. In conclusion, anthelmintic resistance develops in nematode parasite of animals as a consequence of an efficient selection pressure. Early detection of anthelmintic resistance is then crucial : it is not possible to avoid it, but only to delay its development in farm animal industry.
Bashey, Farrah; Lively, Curtis M
Selection is recognized to operate on multiple levels. In disease organisms, selection among hosts is thought to provide an important counterbalance to selection for faster growth within hosts. We performed three experiments, each selecting for a divergence in group size in the entomopathogenic nematode, Steinernema carpocapsae. These nematodes infect and kill insect larvae, reproduce inside the host carcass, and emerge as infective juveniles. We imposed selection on group size by selecting among hosts for either high or low numbers of emerging nematodes. Our goal was to determine whether this trait could respond to selection at the group level, and if so, to examine what other traits would evolve as correlated responses. One of the three experiments showed a significant response to group selection. In that experiment, the high-selected treatment consistently produced more emerging nematodes per host than the low-selected treatment. In addition, nematodes were larger and they emerged later from hosts in the low-selected lines. Despite small effective population sizes, the effects of inbreeding were small in this experiment. Thus, selection among hosts can be effective, leading to both a direct evolutionary response at the population level, as well as to correlated responses in populational and individual traits.
Bose, Neelanjan; Meyer, Jan M; Yim, Joshua J; Mayer, Melanie G; Markov, Gabriel V; Ogawa, Akira; Schroeder, Frank C; Sommer, Ralf J
Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype . To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology. Copyright © 2014 Elsevier Ltd. All rights reserved.
Cyst nematodes produce secreted peptide mimics of plant CLAVATA3/ESR (CLE) peptides likely involved in redirecting CLE signaling pathways active in roots to form unique and essential feeding cells. The hallmark structure of plant CLEs, which includes an N-terminal signal peptide, a highly variable d...
In nematode endemic ecological zones, TGX-1985 – 8F is therefore recommended as it proved to contain some specialized genes that conferred a higher level of tolerance against root- knot nematode, Meloidogyne incognita. Key Words: Glycine max, root – knot nematode, Dominant loci, Mi – 1.2, leucine zipper and R ...
Full Text Available Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae, encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal
Ashrafi, Samad; Helaly, Soleiman; Schroers, Hans-Josef; Stadler, Marc; Richert-Poeggeler, Katja R; Dababat, Abdelfattah A; Maier, Wolfgang
Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae), encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal and nematode
Varlamova, A I; Arkhipov, I A; Odoevskaia, I M; Danilevskaia, N V; Khalikov, S S; Chistiachenko, Iu S; Dushkin, A V
The efficacy of a new fenbendazile formulation produced by nanotechnology-based drug delivery system was investigated in45 sheep naturally infected with gastrointestinal nematodes. The formulation showed 95.6% efficacy against Nematodes spp. at a dose of 1.0 mg/kg dw of its active ingredient and 100% efficacy against other species of gastrointestinal nematodes. Given at a dose of 10 mg/kg dw, the basic drug--fenbendazole (substance) displayed 96.39 and 100% efficacy, respectively.
Maxwell, Philip W.; Chen, Genhui; Webster, John M.; Dunphy, Gary B.
Xenorhabdus nematophilus subsp. dutki, an entomopathogenic bacterium, is vectored by steinernematid nematodes into insects, where it produces broad-spectrum antibiotics. The use of the nematode-bacterium complex against soil-dwelling pest insects could introduce antibiotics into the soil via the dead insect fragments during the emergence phase of the nematodes. Studies on the stability and activities of these antibiotics produced in the insect Galleria mellonella may contribute to assessing t...
Hughes, D P; Kronauer, D J C; Boomsma, J J
A recent study has discovered a novel extended phenotype of a nematode which alters its ant host to resemble ripe fruit. The infected ants are in turn eaten by frugivorous birds that disperse the nematode's eggs.......A recent study has discovered a novel extended phenotype of a nematode which alters its ant host to resemble ripe fruit. The infected ants are in turn eaten by frugivorous birds that disperse the nematode's eggs....
Webster, John M.
A review of the development of entomophilic nematology and a commentary on the potential of entomophilic nematodes in controlling insect pests. The paper considers some of the major contributions to our knowledge of entomophilic nematology; factors involved in insect pest management and how they are applicable to the use of nematodes; nematodes which are most promising as biological control agents; and problems to be solved to facilitate the use of entomophilic nematodes in insect management.
Gasbarre, Louis C
The first documented case of macrocyclic lactone resistance in gastrointestinal (GI) nematodes of cattle was seen in the US approximately 10 years ago. Since that time the increase incidence of anthelmintic resistance has continued at an alarming rate. Currently parasites of the genera Cooperia and/or Haemonchus resistant to generic or brand-name macrocyclic lactones have be demonstrated in more than half of all operations examined. Both of these parasite genera are capable of causing economic losses by decreasing food intake and subsequently animal productivity. Currently, there are no easy and quick means to detect anthelmintic resistant GI nematodes. Definitive identification requires killing of cattle. The most commonly used field detection method is the fecal egg count reduction test (FECRT). This method can be adapted for use as a screening agent for Veterinarians and producers to identify less than desired clearance of the parasites after anthelmintic treatment. Further studies can then define the reasons for persistence of the egg counts. The appearance of anthelmintic resistance is largely due to the development of very effective nematode control programs that have significantly improved the productivity of the US cattle industry, but at the same time has placed a high level of selective pressure on the parasite genome. The challenges ahead include the development of programs that control the anthelmintic resistant nematodes but at the same time result in more sustainable parasite control. The goal is to maintain high levels of productivity but to exert less selective pressures on the parasites. One of the most effective means to slow the development of drug resistance is through the simultaneous use of multiple classes of anthelmintics, each of which has a different mode of action. Reduction of the selective pressure on the parasites can be attained through a more targeted approach to drug treatments where the producer's needs are met by selective
Jasmer, Douglas P; Goverse, Aska; Smant, Geert
Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent reinfection of host species. In addition, development of resistance to nematicides and anthelmintics by these parasites and reduced availability of some nematicides, for environmental protection, pose significant obstacles for current and future prospects of effective parasite control. Due to marked differences in host species, research on animal and plant parasitic nematodes often proceeds independently. Despite the differences between animals and plants, basic cellular properties are shared among these host organisms. Some common properties may be important for mechanisms [homologous or convergent (homoplastic)] by which nematodes successfully infect these diverse hosts or by which animal and plant hosts resist infections by these pathogens. Here we compare host/parasite interactions between plant parasitic nematodes (PPN) and animal parasitic nematodes, with an emphasis on mammalian hosts (MPN). Similarities and differences are considered in the context of progress on molecular dissection of these interactions. A comprehensive coverage is not possible in the space allotted. Instead, an illustrative approach is used to establish examples that, it is hoped, exemplify the value of the comparative approach.
Full Text Available Penicillium marneffei, one of the most important thermal dimorphic fungi, is a severe threat to the life of immunocompromised patients. However, the pathogenic mechanisms of P. marneffei remain largely unknown. In this work, we developed a model host by using nematode Caenorhabditis elegans to investigate the virulence of P. marneffei. Using two P. marneffei clinical isolate strains 570 and 486, we revealed that in both liquid and solid media, the ingestion of live P. marneffei was lethal to C. elegans (P<0.001. Meanwhile, our results showed that the strain 570, which can produce red pigment, had stronger pathogenicity in C. elegans than the strain 486, which can't produce red pigment (P<0.001. Microscopy showed the formation of red pigment and hyphae within C. elegans after incubation with P. marneffei for 4 h, which are supposed to be two contributors in nematodes killing. In addition, we used C. elegans as an in vivo model to evaluate different antifungal agents against P. marneffei, and found that antifungal agents including amphotericin B, terbinafine, fluconazole, itraconazole and voriconazole successfully prolonged the survival of nematodesinfected by P. marneffei. Overall, this alternative model host can provide us an easy tool to study the virulence of P. marneffei and screen antifungal agents.
Rodríguez Martín, José Antonio; Gutiérrez, Carmen; Escuer, Miguel; García-González, Ma Teresa; Campos-Herrera, Raquel; Aguila, Nancy
The Cartagena-La Union mining district, exploited since the end of the 3rd century BC, was one of the world's largest lead producers in the 19th century. Although activity ceased in 1991, today mining residues pose a huge pollution problem. This study characterises lead contents (total and DPTA) and other soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.) using multivariate geostatistical methods in relation to nematode diversity. In this work, trophic groups and metabolic footprints of soil nematodes were measured using 193 samples from the mining, natural and agricultural areas in this district. We explored the relationship between soil health and nematode communities. High lead concentrations were quantified: mean 8,500 mg kg(-1) for total and 340 mg kg(-1) for DPTA in this mining area. Although nematode diversity was broad (81 taxa), their diversity, abundance and metabolic footprints significantly reduced in the mining area. Significant differences in the nematode community structure were observed, and the relative abundance of predators was sensitive to mine and agricultural activities, whilst omnivores reduced only in the agricultural area, and bacterial feeders exhibited a differential response to both anthropogenic disturbances. The total abundance of nematodes, trophic groups and c-p groups correlated negatively with soil Pb contents, and a positive relationship was found with SOM and N, P and K contents. Copyright © 2013 Elsevier B.V. All rights reserved.
GIN infection was associated with 1.4 litres per cow per day less milk and this ... Gastrointestinal nematode (GIN) infections in cattle are of considerable economic importance .... Table 2. Mean faecal egg counts of gastrointestinal nematodes and the 95% confidence ... 3.2 Gastrointestinal nematode species. The pooled ...
L. David Dwinell
The optimum temperature range for pinewood nematodes in southern pine chips was 35 to 40Â° C. Nematode populations declined at temperatures of -20Â°C. at temperatures above 45Â°C. and in anaerobic environments. Wood moisture content and presence of bluestain fungus also influenced nematode populations.
Costa, S.R.; Van der Putten, W.H.; Kerry, B.R.
Plant-parasitic nematodes have traditionally been studied in agricultural systems, where they can be pests of importance on a wide range of crops. Nevertheless, nematode ecology in natural ecosystems is receiving increasing interest because of the role of nematodes in soil food webs, nutrient
Plant-parasitic cyst nematodes secrete CLAVATA3 (CLV3)/ESR(CLE)-like effector proteins. These proteins have been shown to act as ligand mimics of plant CLE peptides and are required for successful nematode infection; however, the receptors for nematode CLE-like peptides have not been identified. Her...
We have surveyed wild cranberry bogs in WI and found three isolates of native nematodes. We have been testing these nematodes as potential biological control agents in for cranberry insect pests including sparganothis fruitworm and flea beetle. The nematodes seem to be effective at finding and killi...
Pratylenchus neglectus and Meloidogyne chitwoodi are the main plant-parasitic nematodes in potato crops of the San Luis Valley, Colorado. Bacterial microbiome (16S rRNA copies per gram of soil) and nematode communities (nematodes per 200 gr of soil) from five different potato farms were analyzed to ...
...-0036] Golden Nematode; Removal of Regulated Areas AGENCY: Animal and Plant Health Inspection Service..., without change, an interim rule that amended the golden nematode regulations by removing the townships of... that the fields in these two townships are free of golden nematode, and we determined that regulation...
.... APHIS-2011-0036] Golden Nematode; Removal of Regulated Areas AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION: Interim rule and request for comments. SUMMARY: We are amending the golden nematode... infested areas. Surveys have shown that the fields in these two townships are free of golden nematode, and...
Oct 5, 2011 ... But in susceptible plant, the psoRPM1 gene expression remained low both before ... cytomembrane and might be interacted with other proteins in cytomembrane to locate ..... the plasma membranes and all cytoplasm of onion.
pathogens and viruses and 6 economically important insect and mite pests attacking ... biological control have been tried with different levels of successes in tomato .... At Dire Dawa, the soil application of BioNem at the rates 200 and 400 ... hatching of M. incognita and BioNem at 2.5 % and 3% concentrations caused 100 ...
Thorpe, Peter; Mantelin, Sophie; Cock, Peter Ja; Blok, Vivian C; Coke, Mirela C; Eves-van den Akker, Sebastian; Guzeeva, Elena; Lilley, Catherine J; Smant, Geert; Reid, Adam J; Wright, Kathryn M; Urwin, Peter E; Jones, John T
The potato cyst nematode Globodera pallida has biotrophic interactions with its host. The nematode induces a feeding structure - the syncytium - which it keeps alive for the duration of the life cycle and on which it depends for all nutrients required to develop to the adult stage. Interactions of G. pallida with the host are mediated by effectors, which are produced in two sets of gland cells. These effectors suppress host defences, facilitate migration and induce the formation of the syncytium. The recent completion of the G. pallida genome sequence has allowed us to identify the effector complement from this species. We identify 128 orthologues of effectors from other nematodes as well as 117 novel effector candidates. We have used in situ hybridisation to confirm gland cell expression of a subset of these effectors, demonstrating the validity of our effector identification approach. We have examined the expression profiles of all effector candidates using RNAseq; this analysis shows that the majority of effectors fall into one of three clusters of sequences showing conserved expression characteristics (invasive stage nematode only, parasitic stage only or invasive stage and adult male only). We demonstrate that further diversity in the effector pool is generated by alternative splicing. In addition, we show that effectors target a diverse range of structures in plant cells, including the peroxisome. This is the first identification of effectors from any plant pathogen that target this structure. This is the first genome scale search for effectors, combined to a life-cycle expression analysis, for any plant-parasitic nematode. We show that, like other phylogenetically unrelated plant pathogens, plant parasitic nematodes deploy hundreds of effectors in order to parasitise plants, with different effectors required for different phases of the infection process.
Tushar Kanti Dutta
Full Text Available With the understanding of nematode-plant interactions at the molecular level, new avenues for engineering resistance have opened up, with RNA interference being one of them. Induction of RNAi by delivering double-stranded RNA (dsRNA has been very successful in the model non-parasitic nematode, Caenorhabditis elegans, while in plant nematodes, dsRNA delivery has been accomplished by soaking nematodes with dsRNA solution mixed with synthetic neurostimulants. The success of in vitro RNAi of target genes has inspired the use of in planta delivery of dsRNA to feeding nematodes. The most convincing success of host-delivered RNAi has been achieved against root-knot nematodes. Plant-mediated RNAi has been shown to lead to the specific down-regulation of target genes in invading nematodes, which had a profound effect on nematode development. RNAi-based transgenics are advantageous as they do not produce any functional foreign proteins and target organisms in a sequence-specific manner. Although the development of RNAi-based transgenics against plant nematodes is still in the preliminary stage, they offer novel management strategy for the future.
Y. Mohammad Alian
rootstocks including Citromelo, Poncirus, Sour Orange, Bakraee, Rough lemon and Off-type some of these rootstocks are common citrus rootstocks in the North and south citrus regions of the present time, therefore it is necessary to choose appropriate rootstock. In addition to it, another purpose (aim of this research is to assess tolerance of new off-type biotype, produced from citrus breeding programs, to citrus nematode under greenhouse conditions in comparison with Citromelo, Poncirus, Sour Orange, Bakraee and Rough lemon which are common citrus rootstock in the North and South provinces of the country. Bakraee is one of the natural types of citrus used in citrus regions of Fars, Hormozgan and Kerman as rootstock of mandarin and orange cultivars for many years. Introductory surveys concerning Bakraee tolerance to coldness, the rot of crown and root, and diseases such as Tristeza, Exocortis and Cachexia were carried out but its tolerance to citrus nematode has not surveyed yet. Recent molecular surveys showed Bakraee relationship with Rough lemon beside, because of appearing unknown disease of citrus trees decline on Bakraee rootstock from the beginning of 1389 in Jiroft mountainous regions, doing etiology studies and investigating its tolerance to disease factors such as citrus nematode is of great importance. Since this nematode is soil parasite and can live in the depth of soil, its chemical control is very difficult. Despite the fact that one of the control methods of it is soil sterilization before citrus planting, but because of increasing environmental risks and bad effects on human health, it is recommended that resistant rootstocks such as Poncirus should be planted in the nematode soil. Also, it is necessary to control plants in selling time from the aspect of infection and, if necessary, to sterilize infected plants in order to prevent infection spread and build healthy orchards. Therefore regarding the fact that rootstocks of Poncirus and Citromelo are resistant
Lawrence, Gary W.; King, Roger; Kelley, Amber T.; Vickery, John
A method and apparatus for remote sensing of parasitic nematodes in plants, now undergoing development, is based on measurement of visible and infrared spectral reflectances of fields where the plants are growing. Initial development efforts have been concentrated on detecting reniform nematodes (Rotylenchulus reniformis) in cotton plants, because of the economic importance of cotton crops. The apparatus includes a hand-held spectroradiometer. The readings taken by the radiometer are processed to extract spectral reflectances at sixteen wavelengths between 451 and 949 nm that, taken together, have been found to be indicative of the presence of Rotylenchulus reniformis. The intensities of the spectral reflectances are used to estimate the population density of the nematodes in an area from which readings were taken.
Ahmed, M.; Sapp, M.; Prior, T.; Karssen, G.; Back, M.
Nematodes represent a species rich and morphologically diverse group of metazoans inhabiting both aquatic and terrestrial environments. Their role as biological indicators and as key players in nutrient cycling has been well documented. Some groups of nematodes are also known to cause significant losses to crop production. In spite of this, knowledge of their diversity is still limited due to the difficulty in achieving species identification using morphological characters. Molecular methodology has provided very useful means of circumventing the numerous limitations associated with classical morphology based identification. We discuss herein the history and the progress made within the field of nematode systematics, the limitations of classical taxonomy and how the advent of high throughput sequencing is facilitating advanced ecological and molecular studies.
Full Text Available The aim of the current study was to describe the role and mechanism of Bacillus amyloliquefaciens Y1 against the root-knot nematode, Meloidogyne incognita, under in vitro and in vivo conditions. Initially, the exposure of the bacterial culture supernatant and crude extract of Y1 to M. incognita significantly inhibited the hatching of eggs and caused the mortality of second-stage juveniles (J2, with these inhibitory effects depending on the length of incubation time and concentration of the treatment. The dipeptide cyclo(d-Pro-l-Leu was identified in B. amyloliquefaciens culture for the first time using chromatographic techniques and nuclear magnetic resonance (NMR 1H, 13C, H-H COSY, HSQC, and HMBC and recognized to have nematocidal activity. Various concentrations of cyclo(d-Pro-l-Leu were investigated for their effect on the hatching of eggs and J2 mortality. Moreover, the in vivo nematocidal activity of the Y1 strain was investigated by conducting pot experiments in which tomato plants were inoculated with M. incognita. Each and every pot was amended 50 mL of fertilizer media (F, or Y1 culture, or nematicide (N (only once, or fertilizer media with N (FN at 1, 2, 3, 4 and 5 weeks after transplantation. The results of the pot experiments demonstrated the antagonistic effect of B. amyloliquefaciens Y1 against M. incognita as it significantly decreases the count of eggs and galls per root of the tomato plant as well as the population of J2 in the soil. Besides, the investigation into the growth parameters, such as the length of shoot, shoot fresh and dry weights of the tomato plants, showed that they were significantly higher in the Y1 strain Y1-treated plants compared to F-, FN- and N-treated plants. Therefore, the biocontrol repertoire of this bacterium opens a new insight into the applications in crop pest control.
Diogo Neves Proença
Full Text Available The pinewood nematode (PWN, Bursaphelenchus xylophilus, has been thought to be the only causal agent of pine wilt disease (PWD, however, since bacteria have been suggested to play a role in PWD, it is important to know the diversity of the microbial community associated to it. This study aimed to assess the microbial community associated with B. xylophilus and with other nematodes isolated from pine trees, Pinus pinaster, with PWD from three different affected forest areas in Portugal. One hundred and twenty three bacteria strains were isolated from PWN and other nematodes collected from 14 P. pinaster. The bacteria strains were identified by comparative analysis of the 16S rRNA gene partial sequence. All except one gram-positive strain (Actinobacteria belonged to the gram-negative Beta and Gammaproteobacteria. Most isolates belonged to the genus Pseudomonas, Burkholderia and to the family Enterobacteriaceae. Species isolated in higher percentage were Pseudomonas lutea, Yersinia intermedia and Burkholderia tuberum. The major bacterial population associated to the nematodes differed according to the forest area and none of the isolated bacterial species was found in all different forest areas. For each of the sampled areas, 60 to 100% of the isolates produced siderophores and at least 40% produced lipases. The ability to produce siderophores and lipases by most isolates enables these bacteria to have a role in plant physiological response. This research showed a high diversity of the microbial community associated with B. xylophilus and other nematodes isolated from P. pinaster with PWD.
Proença, Diogo Neves; Francisco, Romeu; Santos, Clara Vieira; Lopes, André; Fonseca, Luís; Abrantes, Isabel M O; Morais, Paula V
The pinewood nematode (PWN), Bursaphelenchus xylophilus, has been thought to be the only causal agent of pine wilt disease (PWD), however, since bacteria have been suggested to play a role in PWD, it is important to know the diversity of the microbial community associated to it. This study aimed to assess the microbial community associated with B. xylophilus and with other nematodes isolated from pine trees, Pinus pinaster, with PWD from three different affected forest areas in Portugal. One hundred and twenty three bacteria strains were isolated from PWN and other nematodes collected from 14 P. pinaster. The bacteria strains were identified by comparative analysis of the 16S rRNA gene partial sequence. All except one gram-positive strain (Actinobacteria) belonged to the gram-negative Beta and Gammaproteobacteria. Most isolates belonged to the genus Pseudomonas, Burkholderia and to the family Enterobacteriaceae. Species isolated in higher percentage were Pseudomonas lutea, Yersinia intermedia and Burkholderia tuberum. The major bacterial population associated to the nematodes differed according to the forest area and none of the isolated bacterial species was found in all different forest areas. For each of the sampled areas, 60 to 100% of the isolates produced siderophores and at least 40% produced lipases. The ability to produce siderophores and lipases by most isolates enables these bacteria to have a role in plant physiological response. This research showed a high diversity of the microbial community associated with B. xylophilus and other nematodes isolated from P. pinaster with PWD.
Luong, L T; Platzer, E G; Zuk, M; Giblin-Davis, R M
The nematode, Mehdinema alii, occurs in the alimentary canal of the decorated cricket Gryllodes sigillatus. Adult nematodes occur primarily in the hindgut of mature male crickets, whereas juvenile nematodes are found in the genital chambers of mature male and female crickets. Here, we present experimental evidence for the venereal transmission of M. alii in G. sigillatus. Infectivity experiments were conducted to test for transmission via oral-fecal contamination, same-sex contact, and copulation. The infective dauers of the nematode are transferred from male to female crickets during copulation. Adult female crickets harboring infective dauers subsequently transfer the nematode to their next mates. Thus, M. alii is transmitted sexually during copulation.
Beraldo, Paola; Pascotto, Ernesto
Conventional methods to preserve adult nematodes for taxonomic purposes involve the use of fixative or clearing solutions (alcohol, formaldehyde, AFA and lactophenol), which cause morphological alterations and are toxic. The aim of this study is to propose an alternative method based on glycerol-cryopreservation of nematodes for their subsequent identification. Adults of trichostrongylid nematodes from the abomasum of roe deer (Capreolus capreolus Linnaeus) were glycerol-cryopreserved and compared with those fixed in formaldehyde, fresh and frozen without cryoprotectans. Morphology, transparency and elasticity of the anterior and posterior portion of male nematodes were compared, especially the caudal cuticular bursa and genital accessories. The method presented is quick and easy to use, and the quality of nematode specimens is better than that of nematodes fixed by previously used fixatives. Moreover, glycerol cryopreserved nematodes can be stored for a long time at -20 degrees C in perfect condition and they could be suitable for further analyses, such as histological or ultrastructural examinations.
Ronald E Ellis
Full Text Available Intense reproductive competition often continues long after animals finish mating. In many species, sperm from one male compete with those from others to find and fertilize oocytes. Since this competition occurs inside the female reproductive tract, she often influences the outcome through physical or chemical factors, leading to cryptic female choice. Finally, traits that help males compete with each other are sometimes harmful to females, and female countermeasures may thwart the interests of males, which can lead to an arms race between the sexes known as sexually antagonistic coevolution. New studies from Caenorhabditis nematodes suggest that males compete with each other by producing sperm that migrate aggressively and that these sperm may be more likely to win access to oocytes. However, one byproduct of this competition appears to be an increased probability that these sperm will go astray, invading the ovary, prematurely activating oocytes, and sometimes crossing basement membranes and leaving the gonad altogether. These harmful effects are sometimes observed in crosses between animals of the same species but are most easily detected in interspecies crosses, leading to dramatically lowered fitness, presumably because the competitiveness of the sperm and the associated female countermeasures are not precisely matched. This mismatch is most obvious in crosses involving individuals from androdioecious species (which have both hermaphrodites and males, as predicted by the lower levels of sperm competition these species experience. These results suggest a striking example of sexually antagonistic coevolution and dramatically expand the value of nematodes as a laboratory system for studying postcopulatory interactions.
Potato cyst nematode (PCN) is responsible for losses in potato production totalling millions of euros every year in the EC. It is important for growers to know which species is present in their land as this determines its subsequent use. The two species Globodera pallida and Globodera rostochiensis can be differentiated using an allele-specific PCR.
Under the term gastrointestinal nematodes are included numerous parasites species of livestock belonging to the families Strongyloididae (Strongyloides), Strongylidae (Chabertia, Oesophagostomum) Trichostrongylidae (Trichostrongylus, Ostertagia, Teladorsagia, Cooperia, Marshallagia), Molineidae (Nematodirus), Ancylostomatidae (Bunostomum) and Trichuridae (Trichuris). This paper reviews the biomorphology aspects of these parasites as well as the controversy by the taxonomists in the classifications.
Mehrdana, Foojan; Buchmann, Kurt
Parasites from the family Anisakidae are widely distributed in marine fish populations worldwide and mainly nematodes of the three genera Anisakis, Pseudoterranova and Contracaecum have attracted attention due to their pathogenicity in humans. Their life cycles include invertebrates and fish as i...
Potato cyst nematodes (PCN; G. rostochiensis and G. pallida) are internationally-recognized quarantine pests and considered the most devastating pests of potatoes due to annual worldwide yield losses estimated at 12.2%. PCNs continue to spread throughout North America and were recently detected in I...
Snyder, Scott A.
A highly inventive route for the synthesis of a key substance that stimulates potato cyst nematodes to hatch has been developed. This discovery has potential to impact food supplies, as treatment of crops with this compound could alleviate the devastating effect of these parasites.
Aug 4, 2008 ... grower preference or by government restrictions to limit the environmental ... risks associated with chemical control and (c) the pro- vision of ... certain model organisms. The first ... reproductive system (Lilley et al., 2005b), sperm (Urwin .... interference of dual oxidase in the plant nematode Meloidogyne.
Bliss, TJ; Anderson, Margery; Dillman, Adler; Yourick, Debra; Jett, Marti; Adams, Byron J.; Russell, RevaBeth
In a collaborative effort between university researchers and high school science teachers, an inquiry-based laboratory module was designed using two species of insecticidal nematodes to help students apply scientific inquiry and elements of thoughtful experimental design. The learning experience and model are described in this article. (Contains 4…
1973-01-01Established nematode populations are very persistent in the soil. It is known that they need sufficient soil moisture for movement, feeding and reproduction (fig. 5), and that there are adverse soil moisture conditions which they cannot survive. The influence of soil moisture on survival
ZHANG Xiao-Ke; LI Qi; LIANG Wen-Ju; ZHANG Min; BAO Xue-Lian; XIE Zu-Bin
While studies have focused on the use of biochar as soil amendment,little attention has been paid to its effect on soil fauna.The biochar was produced from slow pyrolysis of wheat straw in the present study.Four treatments,no addition (CK) and three rates of biochar addition at 2400 (B1),12000 (B5) and 48000 kg ha-1 (B20),were investigated to assess the effect of biochar addition to soil on nematode abundance and diversity in a microcosm trial in China.The B5 and B20 application significantly increased the total organic carbon and the C/N ratio.No significant difference in total nematode abundance was found among the treatments.The biochar addition to the soil significantly increased the abundance of fungivores,and decreased that of plant parasites.The diversity of soil nematodes was significantly increased by B1 compared to CK.Nematode trophic groups were more effectively indicative to biochar addition than total abundance.
Full Text Available 66 Pampinta breed ewes were studied during milking to evaluate the infection and the effect of gastrointestinal nematode on milk production sheep system. Naturally infected ewes on pasture were randomly allocated to two groups: TG, suppressively treated group every four weeks with levamisole and UG, untreated group. Faecal nematode egg counts and larval differentiation were conducted monthly. Successive groups of worm free tracer lambs were grazed with ewes and then slaughtered for worm counts. Test-day milk yield of individual ewes was recorded and ewe machine-milking period length (MPL were estimated. Faecal egg counts and tracer nematode numbers increased towards midsummer and declined sharply toward the end of the study. TG (188.0 ± 60 liters produced more (p < 0.066 milk liters than UG (171.9 ± 52.2 and TG had significantly more extended (p < 0.041 MPL than those of UG. The present study showed that dairy sheep were negatively affected by worms, even when exposed to short periods of high acute nematode (mainly Haemonchus contortus infection.
Full Text Available Soybean cyst nematode (SCN is the most damaging soybean pest worldwide. To improve soybean resistance to SCN, we employed a soybean seed-coating strategy through combination of three rhizobacterial strains, including Bacillus simple, B. megaterium and Sinarhizobium fredii at various ratios. We found seed coating by such rhizobacterial strains at a ratio of 3:1:1 (thereafter called SN101 produced the highest germination rate and the mortality of J2 of nematodes. Then, the role of soybean seed coating by SN101 in nematode control was evaluated under both greenhouse and two field conditions in Northeast China in 2013 and 2014. Our results showed that SN101 treatment greatly reduced SCN reproduction and significantly promoted plant growth and yield production in both greenhouse and field trials, suggesting that SN101 is a promising seed-coating agent that may be used as an alternative bio-nematicide for controlling SCN in soybean fields. Our findings also demonstrate that combination of multiple rhizobacterial strains needs to be considered in the seed coating for better management of plant nematodes.
Koneru, Sneha L; Salinas, Heilly; Flores, Gilberto E; Hong, Ray L
Insects form the most species-rich lineage of Eukaryotes and each is a potential host for organisms from multiple phyla, including fungi, protozoa, mites, bacteria and nematodes. In particular, beetles are known to be associated with distinct bacterial communities and entomophilic nematodes. While entomopathogenic nematodes require symbiotic bacteria to kill and reproduce inside their insect hosts, the microbial ecology that facilitates other types of nematode-insect associations is largely unknown. To illuminate detailed patterns of the tritrophic beetle-nematode-bacteria relationship, we surveyed the nematode infestation profiles of scarab beetles in the greater Los Angeles area over a five-year period and found distinct nematode infestation patterns for certain beetle hosts. Over a single season, we characterized the bacterial communities of beetles and their associated nematodes using high-throughput sequencing of the 16S rRNA gene. We found significant differences in bacterial community composition among the five prevalent beetle host species, independent of geographical origin. Anaerobes Synergistaceae and sulphate-reducing Desulfovibrionaceae were most abundant in Amblonoxia beetles, while Enterobacteriaceae and Lachnospiraceae were common in Cyclocephala beetles. Unlike entomopathogenic nematodes that carry bacterial symbionts, insect-associated nematodes do not alter the beetles' native bacterial communities, nor do their microbiomes differ according to nematode or beetle host species. The conservation of Diplogastrid nematodes associations with Melolonthinae beetles and sulphate-reducing bacteria suggests a possible link between beetle-bacterial communities and their associated nematodes. Our results establish a starting point towards understanding the dynamic interactions between soil macroinvertebrates and their microbiota in a highly accessible urban environment. © 2016 John Wiley & Sons Ltd.
Nicol, J M; Elekçioğlu, I H; Bolat, N; Rivoal, R
The Cereal Cyst Nematodes (CCNs) are a group of several closely related species which have been documented to cause economic yield loss on rainfed wheat production systems in several part of the world including North Africa, West Asia, China, India, Australia, America and several countries in Europe. The most commonly reported species is Heterodera avenae, however there are at least two other species H. filipjevi and H. latipons are implicated. It is well appreciated that plants under water and nutrient stress suffer greater yield loss. Control of CCNs requires maintaining nematode populations below economic thresholds. Chemicals are not environmentally sustainable or economic and the major emphasis on control has been with host genetic resistance applied with other integrated pest managent options. Unfortunately due to the number of species and pathotype variation genetic control of Cereal Cyst Nematode with plant resistance is complex. Turkey is one of the top ten wheat producers in the world and has identified these nematode as a major biotic constraint in their rainfed wheat systems. In 2001 a new joint intiative was established between CIMMYT International, the Turkish Ministry of Agriculture and (Ukurova University in Adana to understand i) the distribution of cereal nematodes on wheat; ii) assess the economic importance and improve our understanding of the population dynamics iii) culture, screen and assess known sources of resistance and identify new sources to both groups of nematodes; iv) integrate new sources of resistance into bread wheat cultivars for Turkey and International germplasm using conventional and molecular tools; v) investigate other integrated control options such as rotation and different wheat management strategies and finally vi) capacity build scientists to work in this important area. Some highlights of this work will be presented and the newly formed ICCNI - International Cereal Cyst Nematode Initative introduced.
Siddiqui, I A; Shaukat, S S; Khan, A
The aim was to determine the influence of some Aspergillus species on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Six species of Aspergillus, isolated from the rhizosphere of certain crops, produced a variety of secondary metabolites in vitro. Culture filtrate (CF) obtained from Ps. fluorescens strain CHA0 and its2,4-diacetylphloroglucinol overproducing mutant CHA0/pME3424 grown in King's B liquid medium caused significant mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with CF of A. niger enhanced nematicidal and beta-galactosidase activities of fluorescent pseudomonads while A. quadrilineatus repressed such activities. Methanol or ethyl acetate extracts of the CF of A. niger markedly optimized bacterial efficacy to cause nematode deaths while hexane extract of the fungus had no influence on the nematicidal activity of the bacterial strains. A. niger applied alone or in conjunction with the bacterial inoculants inhibited root-knot nematode galling in tomato. On the other hand, A. quadrilineatus used alone or together with CHA0 did not inhibit nematode galling but when used in combination with strain CHA0/pME3424 did reduce galling intensity. Aspergillus niger enhances the production of nematicidal compounds by Ps. fluorescensin vitro and improves biocontrol potential of the bacterial inoculants in tomato while A. quadrilineatus reduces bacterial performance to suppress root-knot nematodes. Rhizosphere harbours a variety of micro-organisms including bacteria, fungi and viruses. Aspergillus species are ubiquitous in most agricultural soils and generally produce a variety of secondary metabolites. Such metabolites synthesized by Aspergillus species may influence the production of nematicidal agents and subsequent biocontrol performance of the bacterial inoculants against plant-parasitic nematodes. This fact needs to be taken into
Martin, T J G; Turner, S J; Fleming, C C
Field trials evaluated the effect of four plant-based bio-fumigants/stimulants on population levels of G. pallida and the resulting potato yields and quality. Three formulations contained seaweed biostimulants (Algifol, Nutridip and Metastim) and one bio-fumigant containing mustard and chilli pepper extracts (Dazitol). These were compared with the fumigant nematicide Nemathorin and untreated control plots. The effect of G. pallida on growing potato crops was assessed by recording haulm characteristics which indicated that the nematicide treatment gave most protection. Levels of PCN juveniles and migratory nematodes were assessed during the trial. Plots treated with Nemathorin and Dazitol had fewest PCN, whilst the highest number of migratory nematodes occurred in fallow plots. Sixteen weeks after planting the nematicide treatment produced highest yield and tuber numbers. Dazitol treatment produced a lower yield but the largest tubers.
Nelson, G. A.; Schubert, W. W.; Kazarians, G. A.; Richards, G. F.
A subset of the Caenorhabditis elegans nematodes flown aboard Biorack on IML-1 was analyzed for the fidelity of development and the mechanics of chromosomes at meiosis. To assess meiosis, mutant worms marked at two linked or unlinked loci were inoculated as heterozygous hermaphrodites and allowed to self fertilize. Mendelian segregation ratios and recombination frequency were measured for offspring produced at 1XG or in microgravity. To assess development, worms and embryos were fixed and stained with the DNA dye, Diamidinophenolindole (DAPI), or antibodies specific for antigens expressed in germ cells, pharyngeal and body wall muscles, and gut cells. The distribution of cytoplasmic determinants, cell nuclei counts and positions were scored to assess symmetry relations and anatomical features.
Quintana, J F; Babayan, S A; Buck, A H
Parasitic nematodes have evolved sophisticated mechanisms to communicate with their hosts in order to survive and successfully establish an infection. The transfer of RNA within extracellular vesicles (EVs) has recently been described as a mechanism that could contribute to this communication in filarial nematodes. It has been shown that these EVs are loaded with several types of RNAs, including microRNAs, leading to the hypothesis that parasites could actively use these molecules to manipulate host gene expression and to the exciting prospect that these pathways could result in new diagnostic and therapeutic strategies. Here, we review the literature on the diverse RNAi pathways that operate in nematodes and more specifically our current knowledge of extracellular RNA (exRNA) and EVs derived from filarial nematodes in vitro and within their hosts. We further detail some of the issues and questions related to the capacity of RNA-mediated communication to function in parasite-host interactions and the ability of exRNA to enable us to distinguish and detect different nematode parasites in their hosts. © 2016 The Authors. Parasite Immunology published by John Wiley & Sons Ltd.
Salinas, Gustavo; Risi, Gastón
The free-living nematode Caenorhabditis elegans is the simplest animal model organism to work with. Substantial knowledge and tools have accumulated over 50 years of C. elegans research. The use of C. elegans relating to parasitic nematodes from a basic biology standpoint or an applied perspective has increased in recent years. The wealth of information gained on the model organism, the use of the powerful approaches and technologies that have advanced C. elegans research to parasitic nematodes and the enormous success of the omics fields have contributed to bridge the divide between C. elegans and parasite nematode researchers. We review key fields, such as genomics, drug discovery and genetics, where C. elegans and nematode parasite research have convened. We advocate the use of C. elegans as a model to study helminth metabolism, a neglected area ready to advance. How emerging technologies being used in C. elegans can pave the way for parasitic nematode research is discussed.
Full Text Available The nematode Caenorhabditis elegans has in recent years been proven to be a powerful in vivo model for testing antimicrobial compounds. We report here that the alkaloid compound Harmane (2-methyl-β-carboline increases the lifespan of nematodes infected with a human pathogen, the Shiga toxin-producing Escherichia coli O157:H7 strain EDL933 and several other bacterial pathogens. This was shown to be unrelated to the weak antibiotic effect of Harmane. Using GFP-expressing E. coli EDL933, we showed that Harmane does not lower the colonization burden in the nematodes. We also found that the expression of the putative immune effector gene F35E12.5 was up-regulated in response to Harmane treatment. This indicates that Harmane stimulates the innate immune response of the nematode; thereby increasing its lifespan during bacterial infection. Expression of F35E12.5 is predominantly regulated through the p38 MAPK pathway; however, intriguingly the lifespan extension resulting from Harmane was higher in p38 MAPK-deficient nematodes. This indicates that Harmane has a complex effect on the innate immune system of C. elegans. Harmane could therefore be a useful tool in the further research into C. elegans immunity. Since the innate immunity of C. elegans has a high degree of evolutionary conservation, drugs such as Harmane could also be possible alternatives to classic antibiotics. The C. elegans model could prove to be useful for selection and development of such drugs.
Jakobsen, Henrik; Bojer, Martin S; Marinus, Martin G; Xu, Tao; Struve, Carsten; Krogfelt, Karen A; Løbner-Olesen, Anders
The nematode Caenorhabditis elegans has in recent years been proven to be a powerful in vivo model for testing antimicrobial compounds. We report here that the alkaloid compound Harmane (2-methyl-β-carboline) increases the lifespan of nematodes infected with a human pathogen, the Shiga toxin-producing Escherichia coli O157:H7 strain EDL933 and several other bacterial pathogens. This was shown to be unrelated to the weak antibiotic effect of Harmane. Using GFP-expressing E. coli EDL933, we showed that Harmane does not lower the colonization burden in the nematodes. We also found that the expression of the putative immune effector gene F35E12.5 was up-regulated in response to Harmane treatment. This indicates that Harmane stimulates the innate immune response of the nematode; thereby increasing its lifespan during bacterial infection. Expression of F35E12.5 is predominantly regulated through the p38 MAPK pathway; however, intriguingly the lifespan extension resulting from Harmane was higher in p38 MAPK-deficient nematodes. This indicates that Harmane has a complex effect on the innate immune system of C. elegans. Harmane could therefore be a useful tool in the further research into C. elegans immunity. Since the innate immunity of C. elegans has a high degree of evolutionary conservation, drugs such as Harmane could also be possible alternatives to classic antibiotics. The C. elegans model could prove to be useful for selection and development of such drugs.
Watermelon (Citrullus lanatus) cultivars are highly susceptible to the southern root-knot nematode (Meloidogyne incognita), with considerable yield losses when this nematode is not managed. Empirical evidence suggested that wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myriocarpus) were highly ...
The interactions of the cyst nematodes Heterodera daverti, H. goldeni and H. zeae with the root-knot nematode Meloidogyne incognita on rice (Oryza sativa) cultivars Giza 178 and Sakha 101 were studied in the greenhouse. Inoculation with H. goldeni alone or one week before inoculation with M. incogni...
The reactions of five rice cultivars to the cyst nematodes Heterodera daverti and H. zeae and the root-knot nematode Meloidogyne incognita were determined in the greenhouse. The results showed that both H. daverti and H. zeae infected and reproduced successfully on some of the tested rice cultivars....
Several species of root-knot nematodes (Meloidogyne spp.) are known to have significant presence on turf grass in golf course greens, particularly in the western United States. Nematodes isolated from a golf course in King Co., Washington were identified as Meloidogyne minor based on analysis of the...
Vetiver, a nonhost grass for certain nematodes, was studied for production of compounds active against the root-knot nematode Meloidogyne incognita. In laboratory assays studying effects on second-stage juvenile (J2) activity and viability, crude vetiver root and shoot extracts were nematotoxic, res...
Numerous pathogens can infect potato, but late blight (Phytophthora infestans (Mont.) de Bary) and potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida are most damaging. Several species of root knot nematodes (RKN) are an emerging threat. Breeders have successfully deployed disease
MIC-3-related genes of cotton (Gossypium spp.) were identified and shown to have root-specific expression, associated with pathogen defense-related function and specifically increased expression in root-knot nematode (RKN) resistant plants after nematode infection. Here we cloned and sequenced MIC-...
Būda, Vincas; Cepulytė-Rakauskienė, Rasa
Linalool is either a toxic compound to a few species of plant parasitic nematodes or attractive to entomopathogenic nematodes. This compound is produced and emitted by several host plants of Globodera rostochiensis and G. pallida, the potato cyst nematodes (PCN). With the aim to reveal the effect of linalool on PCN, laboratory assays were carried out. Survival of PCN second-stage juveniles (J2s) in water + linalool control did not differ; thus, proving linalool to be nontoxic to PCN. Behavioral assays carried out in Petri dishes revealed attractiveness in the form of positive response of J2s of both PCN species towards linalool. Based on these behavioral assays, sensitivity to linalool of G. rostochiensis J2s was higher compared with that of G. pallida J2s. Linalool is the first compound of plant origin to elicit positive response in both PCN species.
Rincones, Johana; Mauléon, Hervé; Jaffe, Klaus
Facultatively sexual entomopathogenic nematodes are a promising model for the experimental study of the adaptive values of sex. Our experiments in the laboratory showed that entomopathogenic nematodes display at least two different strategies in regulating the degree of amphimix as a response to nutritional stress. One strategy promotes the production of males, amphimix and the genetic variability of the offspring, improving the chances for a successful new adaptation. Another strategy increases the production of hermaphrodites at the expense of males, increasing the total number of reproductive individuals and thus the total number of offspring produced. Surprisingly, the strategy used depends upon the strain of symbiotic bacteria the nematodes are growing. The relevance of the results, in helping to discriminate between rival theories for the evolutionary maintenance of sex, is discussed.
Coles, G C; Giordano-Fenton, D J; Tritschler, J P
The activity of an oral drench of moxidectin against nematodes in naturally infected sheep known to harbour Nematodirus species was evaluated at doses of 0.2 and 0.4 mg/kg bodyweight. Moxidectin was 100 per cent effective against nematodes in the abomasum and 100 per cent effective against nematodes in the small intestine except for adult Trichostrongylus species, against which its efficacy was 94 per cent. It was 100 per cent effective against nematodes in the large intestine except for Trichuris ovis, against which its efficacy was 83 per cent.
Institut des Sciences Agronomiques du Rwanda (ISAR), ISAR-Kibungo, Ngoma district, Rwanda ... for sustainable nematode management. Previous studies ..... Technology Development and Transfer project. ... INIBAP, Montpellier, France.
Full Text Available The objectives of the research were to study the effect of P. penetrans and soil solarization on the population of root-knot nematodes (Meloidogyne spp. and the effect of soil solarization on the infectivity of P. penetrans. The research was done in the field with high population of plant parasitic nematode especially root-knot nematodes. Soil solarization was done in dry season by covering the soil before french beans (buncis were planted with transparent plastic and P. penetrans were inoculated before soil solarization. Factorial design in Completely Randomized Design was used in this experiment with the following factors: 1 soil solarization (within 1, 2, and 3 moths; 2 isolates of P. penetrans (i.e. isolate 2 and 3. The research results were: 1 Isolate 2 and 3 of P. penetrans were able to parasitize root-knot nematodes in soil solarized within 1, 2, and 3 months; 2 the length of soil solarization afected the infectivity of P. penetrans on Meloidogyne spp. The percentages of Meloidogyne spp. infected with isolate 2 of P. penetrans in soil solarization within 1, 2, and 3 months were 40.3%; 25.7%, and 10.1%, respectively, whereas in soil inoculated with isolate 3 of P. penetrans were: 37.3%, 10.2%, and 2.2%, respectively; 3 inoculation of P. penetrans reduced the root damage caused by root-knot nematodes (Meloidogyne spp.; and 4 treatment of P. penetrans combined with soil solarization reduced the root damage caused by root-knot nematodes (Meloidogyne spp.. Key words: Pasteuria penetrans, soil solarization, root-knot nematode
Full Text Available Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water, we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.
Self, L H; Bernard, E C
Dogwood canker is a serious production problem of unknown etiology. From May 1985 through April 1989, cankers from 290 flowering dogwood trees in 15 separate nurseries were sampled for nematodes. Seventy-three percent (213) of the cankers contained nematodes. Panagrolaimus rigidus (Schneider) Thorne (115/290) and Aphelenchoides spp. (91/290) were the most frequently collected taxa. Panagrolaimus rigidus was reared on 2% water agar with unidentified bacteria as the food source. Aphelenchoides spp. were reared in antibiotic-amended agar culture with the fungus Glomerella cingulata (Stoneman) Spauld. &Schrenk as a food source. Repeated attempts to culture Aphelenchoides spp. on dogwood callus tissue were unsuccessful. Artificially created stem wounds inoculated with combinations of Aphelenchoides spp. and P. rigidus callused completely in 60 days with no indication of canker development. Very low numbers of nematodes were recovered from inoculated trees, but P. rigidus and one Aphelenchoides sp. were efficient dispersers and occurred in treatments other than those in which they were inoculated.
Rudel, David; Douglas, Chandler; Huffnagle, Ian; Besser, John M.; Ingersoll, Christopher G.
Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegansand P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.
Zago-Gomes Maria P.
Full Text Available We report the results of a retrospective study on the frequency of intestinal nematodes among 198 alcoholic and 440 nonalcoholic patients at the University Hospital Cassiano Antonio Moraes in Vitória, ES, Brazil. The control sample included 194 nonalcoholic patients matched according to age, sex and neighborhood and a random sample of 296 adults admitted at the same hospital. Stool examination by sedimentation method (three samples was performed in all patients. There was a significantly higher frequency of intestinal nematodes in alcoholics than in controls (35.3% and 19.2%, respectively, due to a higher frequency of Strongyloides stercoralis (21.7% and 4.1%, respectively. Disregarding this parasite, the frequency of the other nematodes was similar in both groups. The higher frequency of S. stercoralis infection in alcoholics could be explained by immune modulation and/or by some alteration in corticosteroid metabolism induced by chronic ethanol ingestion. Corticosteroid metabolites would mimic the worm ecdisteroids, that would in turn increase the fecundity of females in duodenum and survival of larvae. Consequently, the higher frequency of Strongyloides larvae in stool of alcoholics does not necessarily reflect an increased frequency of infection rate, but only an increased chance to present a positive stool examination using sedimentation methods.
Full Text Available Root-knot nematodes (Meloidogyne spp. are among the main pathogens of greenhouse crops worldwide. Plant resistance is currently the method of choice for controlling these pests. To select resistant tomato against two common species of root-knot nematodes, M. incognita and M. arenaria, 36 commercial tomato (Lycopersicon esculentum Mill. cultivars were screened. Seventeen tomato cultivars were resistant to both root-knot nematodes: six in cherry tomato, ‘Tenten’, ‘Cadillac’, ‘Cutti’, ‘Sweet’, ‘Ppotto’, ‘Lycopin-9’, eight in globe tomato, ‘Lovely 240’, ‘Dotaerang Dia’, ‘Cupirang’, ‘Dotaerang Master’, ‘Super Dotaerang’, ‘Dotaerang Season’, ‘Miroku’, ‘Hoyong’, and three in root stock, ‘Special’, ‘Fighting’, and ‘Magnet’.
Full Text Available Nematodes are considered excellent models for understanding fundamental aspects of neuron function. However, nematodes are less frequently used as models for examining the evolution of nervous systems. While the habitats and behaviors of nematodes are diverse, the neuroanatomy of nematodes is often considered highly conserved. A small number of nematode species greatly influences our understanding of nematode neurobiology. The free-living species Caenorhabditis elegans and, to a lesser extent, the mammalian gastrointestinal parasite Ascaris suum are, historically, the primary sources of knowledge regarding nematode neurobiology. Despite differences in size and habitat, C. elegans and Ascaris suum share a surprisingly similar neuroanatomy. Here, we examined species across several clades in the phylum Nematoda and show that there is a surprising degree of neuroanatomical variation both within and among nematode clades when compared to C. elegans and Ascaris. We found variation in the numbers of neurons in the ventral nerve cord and dye-filling pattern of sensory neurons. For example, we found that Pristionchus pacificus, a bacterial feeding species used for comparative developmental research, had 20% fewer ventral cord neurons compared to C. elegans. Steinernema carpocapse, an insect-parasitic nematode capable of jumping behavior, had 40% more ventral cord neurons than C. elegans. Interestingly, the non-jumping congeneric nematode, S. glaseri showed an identical number of ventral cord neurons as S. carpocapsae. There was also variability in the timing of neurodevelopment of the ventral cord with two of five species that hatch as second-stage juveniles showing delayed neurodevelopment. We also found unexpected variation in the dye-filling of sensory neurons among examined species. Again, sensory neuron dye-filling pattern did not strictly correlate with phylogeny. Our results demonstrate that variation in nematode neuroanatomy is more prevalent
Choi, Jae Im; Yoon, Kyoung-Hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin
Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator-prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds.
Choi, Jae Im; Yoon, Kyoung-hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin
Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator–prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds. PMID:26241504
Livshits, Leonid; Gross, Einav
Cysteine catabolism by gut microbiota produces high levels of sulfide. Excessive sulfide can interfere with colon function, and therefore may be involved in the etiology and risk of relapse of ulcerative colitis, an inflammatory bowel disease affecting millions of people worldwide. Therefore, it is crucial to understand how cells/animals regulate the detoxification of sulfide generated by bacterial cysteine catabolism in the gut. Here we describe a simple and cost-effective way to explore the mechanism of sulfide toxicity in the nematode Caenorhabditis elegans ( C. elegans ). •A rapid cost-effective method to quantify and study sulfide tolerance in C. elegans and other free-living nematodes.•A cost effective method to measure the concentration of sulfide in the inverted plate assay.
The paper reviews genetic resistance of sheep to gastrointestinal nematodes from the standpoint of resistance to the parasites themselves and of resistance to the diseases they produce. Attention is focused on infections with the abomasal parasite Haemonchus contortus and the small intestinal nematode Trichostrongylus colubriformis, and on the role of nuclear techniques both in verifying the existence of genetically based differences in resistance to these parasites and in gaining an understanding of the mechanisms involved. It is concluded that resistance to disease per se is much less important than resistance to parasite establishment and survival and that genetic studies could contribute substantially to the identification of the factors and variables responsible for the present inability to successfully vaccinate young animals against these infections. (author)
Matthews, Benjamin F; Beard, Hunter; MacDonald, Margaret H; Kabir, Sara; Youssef, Reham M; Hosseini, Parsa; Brewer, Eric
During pathogen attack, the host plant induces genes to ward off the pathogen while the pathogen often produces effector proteins to increase susceptibility of the host. Gene expression studies of syncytia formed in soybean root by soybean cyst nematode (Heterodera glycines) identified many genes altered in expression in resistant and susceptible roots. However, it is difficult to assess the role and impact of these genes on resistance using gene expression patterns alone. We selected 100 soybean genes from published microarray studies and individually overexpressed them in soybean roots to determine their impact on cyst nematode development. Nine genes reduced the number of mature females by more than 50 % when overexpressed, including genes encoding ascorbate peroxidase, β-1,4-endoglucanase, short chain dehydrogenase, lipase, DREPP membrane protein, calmodulin, and three proteins of unknown function. One gene encoding a serine hydroxymethyltransferase decreased the number of mature cyst nematode females by 45 % and is located at the Rhg4 locus. Four genes increased the number of mature cyst nematode females by more than 200 %, while thirteen others increased the number of mature cyst nematode females by more than 150 %. Our data support a role for auxin and ethylene in susceptibility of soybean to cyst nematodes. These studies highlight the contrasting gene sets induced by host and nematode during infection and provide new insights into the interactions between host and pathogen at the molecular level. Overexpression of some of these genes result in a greater decrease in the number of cysts formed than recognized soybean cyst nematode resistance loci.
Mulder, C.; Helder, J.; Vervoort, M.T.W.; Vonk, J.A.
Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding
Li, J.; Vincx, M.; Herman, P.M.J.
We developed a time dynamic model to investigate the temporal dynamics of nematode community in the brackish zone of the Westerschelde Estuary. The biomass of four nematode feeding groups observed from March 1991 to February 1992 is used to calibrate the model. Using environmental data as the input,
The incidence and intensity of nematode infection was investigated in Nile tilapia Oreochromis niloticus from Lake Kyoga, Uganda and 11% of the 406 fish examined were parasitized by nematodes of the genus Contracaecum. The prevalence of these parasites was greatest in the smallest and largest size classes, but this ...
This is the first of three volumes dealing with the most abundant group of animals on the sea-bed and sea-shore, the free-living marine nematodes, and is devoted to those marine nematodes belonging to the subclass Enoplia. Separate volumes will deal with the orders Chromadorida and. Monhysterida. To most marine ...
in organic crop production fields can favour or inhibit nematode build-up. ... that nematode control strategies employed on the organic field might be less effective than expected. ... Method. Study site. Soil samples were collected from an organic vegetable field and a conventional ..... chemical analysis: a practical handbook.
Phytonematodes use a stylet and secreted effectors to invade host tissues and extract nutrients to support their growth and development. The molecular function of nematode effectors is currently the subject of intense investigation. In this review, we summarize our current understanding of nematode ...
Jones, J.T.; Reavy, B.; Smant, G.; Prior, A.E.
We report the cloning and characterisation of full-length DNAs complementary to RNA (cDNAs) encoding two glutathione peroxidases (GpXs) from a plant parasitic nematode, the potato cyst nematode (PCN) Globodera rostochiensis. One protein has a functional signal peptide that targets the protein for
Rouppe van der Voort, J.N.A.M.
The thesis describes strategies for genetic mapping of the genomes of the potato cyst nematode and potato. Mapping in cyst nematodes was achieved by AFLP genotyping of single cysts and subsequent segregation analysis in a family of sibling populations. The genetic map of Globodera
This thesis describes a first attempt to investigate the biological activity of cyst nematode secretions on plant cell proliferation and the molecular mechanisms underlying feeding cell development in plant roots upon cyst nematode infection.
To investigate the role of
This thesis describes the genomic localisation and organisation of loci that harbour resistance to the potato cyst nematode species Globodera pallida and G. rostochiensis . Resistance to the potato cyst nematodes G. pallida and G. rostochiensis is an important aspect in potato breeding. To gain
Bongers, T.; Ferris, H.
Four of every five multicellular animals on the planet are nematodes. They occupy any niche that provides an available source of organic carbon in marine, freshwater and terrestrial environments. Nematodes vary in sensitivity to pollutants and environmental disturbance. Recent development of indices
Bain, Odile; Diniz, Daniel G.; Nascimento dos Santos, Jeannie; Pinto de Oliveira, Norimar; Frota de Almeida, Izabela Negrão; Frota de Almeida, Rafael Negrão; Frota de Almeida, Luciana Negrão; Dantas-Torres, Filipe; Sobrinho, Edmundo Frota de Almeida
A male nematode was extracted from iris fibers of a man from the Brazilian Amazon region. This nematode belonged to the genus Pelecitus but was distinct from the 16 known species in this genus. Similarities with Pelecitus spp. from neotropical birds suggested an avian origin for this species. PMID:21529397
...] Pale Cyst Nematode; Update of Quarantined Areas AGENCY: Animal and Plant Health Inspection Service...: Background The pale cyst nematode (PCN, Globodera pallida) is a major pest of potato crops in cool... made changes to the area in the State of Idaho that is quarantined to prevent the spread of pale cyst...
The cyst nematodes are an important group of plant-parasitic nematodes that cause billions of dollars in economic damage to crops every year. This article reviews a recently published, two-volume monograph that describes the morphological and molecular characteristics of these agriculturally signif...
...] Pale Cyst Nematode; Update of Quarantined Areas AGENCY: Animal and Plant Health Inspection Service... made changes to the area in the State of Idaho that is quarantined to prevent the spread of pale cyst nematode. The description of the quarantined area was updated on April 26, 2010. As a result of these...
Samish, M; Alekseev, E; Glazer, I
Entomopathogenic nematodes (EPNs) are lethal to ticks even though they do not use their normal propagation cycle within tick cadavers. The tick Boophilus annulatus was found to be far more susceptible to EPNs than Hyalomma excavatum, Rhipicephalus bursa, or Rhipicephalus sanguineus. Ticks seem to be less susceptible to nematodes when feeding on a host. Preimaginal tick stages were less susceptible to nematodes than adult ticks. The mortality rate of unfed females was highest, followed by unfed males, and engorged females. The virulence of nematodes to ticks varied greatly among different nematode strains. In most cases, the Heterorhabditis sp. strains were the most virulent strains tested in petri dishes. In buckets containing sandy soil sprayed with 50 nematodes/cm2 and engorged B. annulatus females, the LT50 of the ticks was less than five days. The addition of manure to soil or a manure extract to petri dishes reduced nematode virulence. Since ticks spend most of their life cycle in the upper humid layer of the ground, and many nematode strains share this same ecological niche, the use of EPNs for biocontrol of ticks appears promising.
Steyaert, M.; Moodley, L.; Vanaverbeke, J.; Vandewiele, S.L.; Vincx, M.
The impact of oxygen on the vertical distribution of an intertidal nematode community was investigated in a manipulation experiment with sediments collected from the Oosterschelde (The Netherlands). The vertical distribution of nematodes was examined in response to sediment inversion in perspex
In the summer of 2015, an effort was made in central Wisconsin to find an entomopathogenic nematode capable controlling Wisconsin’s cranberry pests. Using a standard baiting method, a nematode of the Oscheius genus was collected from the mossy, sandy, peat-filled soils of a wild cranberry marsh. Thi...
Information concerning the occurrence and distribution of the cyst nematodes (Heterodera spp. and Globodera spp.) in Egypt is important to assess their potential to cause economic damage to many crop plants. A nematode survey was conducted in Alexandria, El Behera and Sohag governorates during 2012-...
The rest of the mutants namely Ro Im V4 6-1-2 and Si Im V4 6-2-5 were found to be susceptible to nematodes. The resistant and moderately resistant mutants of banana could be further used in breeding programmes as well as being recognized as potential cultivars of commerce. Key words: Banana, nematode, resistance, ...
Berg, van den W.; Hartsema, O.; Nijs, Den J.M.F.
A series of proficiency tests on potato cyst nematode (PCN; n=29) and free-living stages of Meloidogyne and Pratylenchus (n=23) were investigated to determine the accuracy and precision of the nematode counts and to gain insights into possible trends and potential improvements. In each test, each
Agneessens, J.; Claerebout, E.; Dorny, P.; Borgsteede, F.H.M.; Vercruysse, J.
Over a period of 1 year, from November 1997 to October 1998, the abomasa, blood and faecal samples of 121 dairy cows in Belgium were collected and examined for nematode infections. Nematodes were present in the abomasa of 110 animals. Ostertagia was found in all 110, Trichostrongylus was seen in 65
Schmidt, Liesbeth M; Hewlett, Thomas E; Green, April; Simmons, Lee J; Kelley, Karen; Doroh, Mark; Stetina, Salliana R
Rotylenchulus reniformis is one of 10 described species of reniform nematodes and is considered the most economically significant pest within the genus, parasitizing a variety of important agricultural crops. Rotylenchulus reniformis collected from cotton fields in the Southeastern US were observed to have the nematode parasitic bacterium Pasteuria attached to their cuticles. Challenge with a Pasteuria-specific monoclonal antibody in live immuno-fluorescent assay (IFA) confirmed the discovery of Pasteuria infecting R. reniformis. Scanning and transmission electron microscopy were employed to observe endospore ultrastructure and sporogenesis within the host. Pasteuria were observed to infect and complete their life-cycle in juvenile, male and female R. reniformis. Molecular analysis using Pasteuria species-specific and degenerate primers for 16s rRNA and spoII, and subsequent phylogenetic assessment, placed the Pasteuria associated with R. reniformis in a distinct clade within established assemblages for the Pasteuria infecting phytopathogenic nematodes. A global phylogenetic assessment of Pasteuria 16s rDNA using the Neighbor-Joining method resulted in a clear branch with 100% boot-strap support that effectively partitioned the Pasteuria infecting phytopathogenic nematodes from the Pasteuria associated with bacterivorous nematodes. Phylogenetic analysis of the R. reniformis Pasteuria and Pasteuria spp. parasitizing a number of economically important plant parasitic nematodes revealed that Pasteuria with different host specificities are closely related and likely constitute biotypes of the same species. This suggests host preference, and thus effective differentiation and classification are most likely predicated by an influential virulence determinant(s) that has yet to be elucidated. Pasteuria Pr3 endospores produced by in vitro fermentation demonstrated efficacy as a commercial bionematicide to control R. reniformis on cotton in pot tests, when applied as a seed
Infective-stage juveniles of Neoaplacetana carpocapsae were acutely sensitive to short uv radiation (254 nm) and natural sunlight. High nematode mortality, although delayed, accompanied uv exposure. Irradiation rapidly reduced nematode pathogenicity, so that nematodes exposed for 7 min were unable to cause lethal infections in Galleria mallonella larvae. Moreover, the median survival time of Galleria larvae increased progressively as nematode exposure to uv was lengthened. Inhibition of nematode reproduction and development was noted at exposure periods more than 2.45 and 5 min, respectively. However, irradiation did not appear to affect juvenile motility. Exposure to direct sunlight also reduced pathogenicity, in a range from 6.9 to 94.9% at 30 and 60 min of exposure, respectively. Long uv (366 nm) did not affect juveniles at the exposures tested
Full Text Available Phytopathogenic nematodes represent one of the most important groups of pathogens in crops. The use of chemical to control the nematodes attack in crops is decreasing every year due to the concern of the toxicity and side effects of such compounds. In the course for finding alternatives to the use of chemicals, biological control of nematodes is gaining much attention. Some saprotrophic fungi are able to feed on invertebrates, thus becoming efficient agents of control. In this study, three species of basidiomycetes were analyzed for their potential to be used as control agents of phytopathogenic nematodes. Through on in vitro investigation of these potential, one strain – Gymnopilus junonius was further selected for a pot test against Meloidogyne incognita, a very important phytopathogenic species of nematodes. The fungal treatment strongly decreased the M. incognita population on the tested pots, proving the potential of G. junonius strain to be used in biocontrol.
Ross, J L; Ivanova, E S; Hatteland, B A; Brurberg, M B; Haukeland, S
A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identiﬁed by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in this study: Alloionema appendiculatum, Agfa flexilis, Angiostoma limacis, Angiostoma sp. and Phasmarhabditis hermaphrodita. Of these species, only one nematode was previously undescribed (Angiostoma sp.). This is the first record of the presence of A. appendiculatum, A. flexilis and A. limacis in Norway.
Hazir, Selcuk; Shapiro-Ilan, David I; Hazir, Canan; Leite, Luis G; Cakmak, Ibrahim; Olson, Dawn
The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs. Copyright © 2016
Ignatowicz, S.; Karnkowski, W.
Juvenile and adult nematodes emerged from onion and garlic samples on the 3 rd week after irradiation with doses up to 0.5 kGy and from potato treated with doses up to 2.0 kGy. However, irradiation of onion infected with Ditylenchus dipsaci caused the inhibition of the development and growth of juvenile nematodes to mature forms. Doses of gamma radiation ranging from 0.1 to 0.5 kGy had only a slight effect, if any, on the development and growth of D. dipsaci nematodes infecting garlic, but they increased juvenile mortality. Gamma radiation at doses up to 2.0 kGy induced increased mortality of nematode juveniles of the potato tuber nematode, D. destructor but less so inhibited their development to mature forms. Nematodes were found to be resistant to irradiation treatment. Therefore the use of gamma irradiation for nematode disinfestation of agricultural products seems to be impractical, if the aim of the treatment is to kill these pests within a few weeks. The level of radiation required to kill nematodes in infected plants would damage plant tissues so that the further storage of vegetables will be impossible. (author). 22 refs, 3 figs, 2 tabs
Francesca De Luca
Full Text Available PCR-RFLP and sequencing approaches of ribosomal DNA are being used to study taxonomy, molecular identification and phylogeny of plant parasitic nematodes. In this paper, we discuss on the usefulness of ITS PCRRFLP analysis to differentiate among longidorid species. In addition, we examined how well ITS PCR-RFLP differentiated between longidorid species, and how well sequencing of two different ribosomal regions, the ITS containing region and D1-D2 domains of the 26S rDNA, were able to infer phylogenetic relationships among those same species. These methods and their advantages in identifying longidorids and establishing their phylogenetic relationships are examined and discussed.
Kirillova, N Iu; Kirillov, A A; Vekhnik, V P
Fauna of parasitic nematodes from Chiroptera of the Samarskaya Luka has been studied. Seven nematode species has been recorded. Numbers of host specimens, indices of extensiveness and intensiveness of the invasion, parasite abundance, and brief characteristics of the nematode species are given. Some nematode species were for the first time recorded in bats of Russia.
Spiral nematodes (Helicotylenchus spp.) are common plant-parasitic nematodes in fields of many crops. In June 2015, two soil samples were collected from a soybean field in Richland County, ND. Nematodes were extracted from soil using the sugar centrifugal flotation method. Plant-parasitic nematodes ...
Full Text Available The root knot nematode, Meloidogyne incognita, is an obligate parasite that causes significant damage to a broad range of host plants. Infection is associated with secretion of proteins surrounded by proliferating cells. Many parasites are known to secrete effectors that interfere with plant innate immunity, enabling infection to occur; they can also release pathogen-associated molecular patterns (PAMPs, e.g., flagellin that trigger basal immunity through the nematode stylet into the plant cell. This leads to suppression of innate immunity and reprogramming of plant cells to form a feeding structure containing multinucleate giant cells. Effectors have generally been discovered using genetics or bioinformatics, but M. incognita is non-sexual and its genome sequence has not yet been reported. To partially overcome these limitations, we have used mass spectrometry to directly identify 486 proteins secreted by M. incognita. These proteins contain at least segmental sequence identity to those found in our 3 reference databases (published nematode proteins; unpublished M. incognita ESTs; published plant proteins. Several secreted proteins are homologous to plant proteins, which they may mimic, and they contain domains that suggest known effector functions (e.g., regulating the plant cell cycle or growth. Others have regulatory domains that could reprogram cells. Using in situ hybridization we observed that most secreted proteins were produced by the subventral glands, but we found that phasmids also secreted proteins. We annotated the functions of the secreted proteins and classified them according to roles they may play in the development of root knot disease. Our results show that parasite secretomes can be partially characterized without cognate genomic DNA sequence. We observed that the M. incognita secretome overlaps the reported secretome of mammalian parasitic nematodes (e.g., Brugia malayi, suggesting a common parasitic behavior and a possible
Full Text Available Up to now the visual inspection of mobility of isolated anisakid larvae serves as a measure of viability and possible risk of infection. This paper presents a new method to rule out unreliability – caused by the temporary immobility of the larvae and by the human uncertainty factor of visual observation. By means of a Near infrared (NIR imaging method, elastic curvature energies and geometric shape parameters were determined from contours, and used as a measure of viability. It was based on the modelling of larvae as a cylindrical membrane system. The interaction between curvatures, contraction of the longitudinal muscles, and inner pressure enabled the derivation of viability from stationary form data. From series of spectrally signed images within a narrow wavelength range, curvature data of the larvae were determined. Possible mobility of larvae was taken into account in statistical error variables. Experiments on individual living larvae, long-term observations of Anisakis larvae, and comparative studies of the staining method and the VTD measurements of larvae from the tissue of products confirmed the effectiveness of this method. The VTD differentiated clearly between live and dead nematode larvae isolated from marinated, deep-frozen and salted products. The VTD has been proven as excellent method to detect living anisakid nematode larvae in fishery products and is seen as useful tool for fish processing industry and control authorities. Keywords: Biophysics
de Brida, Andressa Lima; Rosa, Juliana Magrinelli Osório; Oliveira, Cláudio Marcelo Gonçalves de; Castro, Bárbara Monteiro de Castro E; Serrão, José Eduardo; Zanuncio, José Cola; Leite, Luis Garrigós; Wilcken, Silvia Renata Siciliano
Entomopathogenic nematodes (EPNs) (Steinernematidae and Heterorhabditidae) can control pests due to the mutualistic association with bacteria that kill the host by septicemia and make the environment favorable for EPNs development and reproduction. The diversity of EPNs in Brazilian soils requires further study. The identification of EPNs, adapted to environmental and climatic conditions of cultivated areas is important for sustainable pest suppression in integrated management programs in agricultural areas of Brazil. The objective was to identify EPNs isolated from agricultural soils with annual, fruit and forest crops in Brazil. Soil samples were collected and stored in 250 ml glass vials. The nematodes were isolated from these samples with live bait traps ([Galleria mellonella L. (Lepidoptera: Pyralidae) larvae]. Infective juveniles were collected with White traps and identified by DNA barcoding procedures by sequencing the D2/D3 expansion of the 28S rDNA region by PCR. EPNs identified in agricultural areas in Brazil were Heterorhabditis amazonensis, Metarhabditis rainai, Oscheios tipulae and Steinernema rarum. These species should be considered pest biocontrol agents in Brazilian agricultural areas.
Armour, J; Duncan, M
Most economically important cattle nematodes are able to arrest their larval development within the host - entering a period of dormancy or hypobiosis. Arrested larvae have a low death rate, and large numbers can accumulate in infected cattle during the grazing season. Because of this, outbreaks of disease caused by such nematodes can occur at times when recent infection with the parasites could not have occurred, for example during winter in temperature northern climates when cattle are normally housed. The capacity to arrest is a heritable trait. It is seen as an adaptation by the parasite to avoid further development to its free-living stages during times when the climate is unsuitable for free-living survival. But levels of arrestment can vary markedly in different regions, in different cattle, and under different management regimes. Climatic factors, previous conditioning, host immune status, and farm management all seem to affect arrestment levels. In this article, James Armour and Mary Duncan review the biological basis of the phenomenon, and discuss the apparently conflicting views on how it is controlled.
van den Elsen, Sven; Ave, Maaike; Schoenmakers, Niels; Landeweert, Renske; Bakker, Jaap; Helder, Johannes
Potato cyst nematodes (PCNs) are quarantine organisms, and they belong to the economically most relevant pathogens of potato worldwide. Methodologies to assess the viability of their cysts, which can contain 200 to 500 eggs protected by the hardened cuticle of a dead female, are either time and labor intensive or lack robustness. We present a robust and cost-efficient viability assay based on loss of membrane integrity upon death. This assay uses trehalose, a disaccharide present at a high concentration in the perivitelline fluid of PCN eggs, as a viability marker. Although this assay can detect a single viable egg, the limit of detection for regular field samples was higher, ≈10 viable eggs, due to background signals produced by other soil components. On the basis of 30 nonviable PCN samples from The Netherlands, a threshold level was defined (ΔA(trehalose) = 0.0094) below which the presence of >10 viable eggs is highly unlikely (true for ≈99.7% of the observations). This assay can easily be combined with a subsequent DNA-based species determination. The presence of trehalose is a general phenomenon among cyst nematodes; therefore, this method can probably be used for (for example) soybean, sugar beet, and cereal cyst nematodes as well.
Maria José M. DA CUNHA
Full Text Available Identification of species and virulence groups of potato cyst nematodes (PCN, Globodera pallida and G. rostochiensis, present in field populations is important in the control of these nematodes by means of resistant cultivars. In order to characterize the virulence of Globodera spp. isolates from Portugal, 43 G. rostochiensis and three G. pallida isolates were evaluated by measuring their multiplication rates on a susceptible potato cultivar and five differential potato genotypes in a growth chamber pot experiment. Principal Component Analysis and Hierarchical Cluster Analysis showed that the reproduction rates were different in terms of both the numbers of eggs and the numbers of cysts produced. Portuguese isolates of PCN were more virulent on genotypes derived from Solanum vernei than on genotypes derived from other Solanum resistance sources, and there was a significant nematode isolate × host genotype interaction. The virulence bioassay clearly distinguished the two PCN species but failed to differentiate isolates into pathotypes. There was a wide and continuous range of virulence to the resistant genotypes, especially in G. rostochiensis isolates.
Full Text Available Entomopathogenic nematodes are a subgroup of insect-parasitic nematodes that are used in biological control as alternatives or supplements to chemical pesticides. Steinernema scapterisci is an unusual member of the entomopathogenic nematode guild for many reasons including that it is promiscuous in its association with bacteria, it can reproduce in the absence of its described bacterial symbiont, and it is known to have a narrow host range. It is a powerful comparative model within the species and could be used to elucidate parasite specialization. Here we describe a new method of efficiently producing large numbers of S. scapterisci infective juveniles (IJs in house crickets and for quantifying parasitic activation of the IJs upon exposure to host tissue using morphological features. We found that parasite activation is a temporal process with more IJs activating over time. Furthermore, we found that activated IJs secrete a complex mixture of proteins and that S. scapterisci IJs preferentially activate upon exposure to cricket tissue, reaffirming the description of S. scapterisci as a cricket specialist.
Nematode-trapping fungi are soil-living organisms with the unique ability to capture and infect free-living nematodes. The interest in studying these fungi arises from their potential use as biological control agents for plant- and animal-parasitic nematodes. To enter the parasitic stage, nematode-trapping fungi develop different kinds of trapping structures. In order to understand more about the evolution of parasitism in the nematode-trapping fungi and to identify virulence factors in these...
Full Text Available BACKGROUND: The rice white tip nematode Aphelenchoides besseyi, a devastating nematode whose genome has not been sequenced, is distributed widely throughout almost all the rice-growing regions of the world. The aims of the present study were to define the transcriptome of A. besseyi and to identify parasite-related, mortality-related or host resistance-overcoming genes in this nematode. METHODOLOGY AND PRINCIPAL FINDINGS: Using Solexa/Illumina sequencing, we profiled the transcriptome of mixed-stage populations of A. besseyi. A total of 51,270 transcripts without gaps were produced based on high-quality clean reads. Of all the A. besseyi transcripts, 9,132 KEGG Orthology assignments were annotated. Carbohydrate-active enzymes of glycoside hydrolases (GHs, glycosyltransferases (GTs, carbohydrate esterases (CEs and carbohydrate-binding modules (CBMs were identified. The presence of the A. besseyi GH45 cellulase gene was verified by in situ hybridization. Given that 13 unique A. besseyi potential effector genes were identified from 41 candidate effector homologs, further studies of these homologs are merited. Finally, comparative analyses were conducted between A. besseyi contigs and Caenorhabditis elegans genes to look for orthologs of RNAi phenotypes, neuropeptides and peptidases. CONCLUSIONS AND SIGNIFICANCE: The present results provide comprehensive insight into the genetic makeup of A. besseyi. Many of this species' genes are parasite related, nematode mortality-related or necessary to overcome host resistance. The generated transcriptome dataset of A. besseyi reported here lays the foundation for further studies of the molecular mechanisms related to parasitism and facilitates the development of new control strategies for this species.
van Houtert, M F; Sykes, A R
Resistance and resilience of the ruminant host to gastrointestinal (GI) parasitic nematode infections are influenced by many factors, including nutrition. This review examines the effects of host nutrition on the ability of ruminants to withstand GI nematode infections. Firstly the effects of infection on host metabolism are summarised briefly. An important factor in the pathogenesis is a reduction in feed intake by the host. Gut nematodes also increase endogenous protein losses, which result in net loss of amino acids to the parasitised host, though energy and mineral metabolism are also perturbed. The indications are that the major nutritional change is in protein metabolism. Resilience (the ability of an animal to withstand the effects of infection) can be enhanced markedly by increasing metabolisable protein supply and to a lesser extent metabolisable energy supply. Resistance to GI nematodes (ability of host to prevent establishment and/or development of infection) is also influenced by diet, particularly metabolisable protein supply. While there do not appear to be any effects of host nutrition on establishment of infective larvae, the rate of rejection of adult worms can be enhanced by improved nutrition. The exact nutritional requirements or the mechanisms involved are not known. It appears that the effects of improving nutritional status on host resilience are more clearly defined than effects on host resistance. The implication of changes in host resistance with nutritional state for host productivity need to be better described. Understanding the role of nutrition in improving both resistance and resilience of the host to GI parasites will be important if producers are to make better use of host acquired immunity and reduce dependence on pesticides for prophylaxis.
Gruzdeva, L. I.; Matveeva, E. M.; Kovalenko, T. E.
Changes taking place in the communities of soil nematodes of an artificially sown meadow under the impact of annually applied mineral fertilizers have been studied in a field experiment for nine years. It is shown that changes in the species composition, trophic structure, and numbers of nematodes from different genera depend on the fertilizer applied and on the competitiveness of the plant species grown. The spectra of nematode genera sensitive to the complete mineral fertilizer (NPK) and to the particular nutrients have been identified with the use of a number of parameters, including the maturity index of nematode communities, the biotope preferences of the particular nematode genera, and the general pattern of nematode habitats. The results obtained in this study can be used to assess the effect of mineral fertilizers on the soil fauna and to suggest optimum application rates of mineral fertilizers ensuring the sustainable development of meadow herbs. The use of the data on the trophic structure of nematode communities for predicting the ways of organic matter decomposition in the soil is discussed.
Ruark, Casey L; Gardner, Michael; Mitchum, Melissa G; Davis, Eric L; Sit, Tim L
The study of invertebrate-and particularly nematode-viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies.
Midha, Ankur; Schlosser, Josephine; Hartmann, Susanne
Parasitic nematode infections are widespread in nature, affecting humans as well as wild, companion, and livestock animals. Most parasitic nematodes inhabit the intestines of their hosts living in close contact with the intestinal microbiota. Many species also have tissue migratory life stages in the absence of severe systemic inflammation of the host. Despite the close coexistence of helminths with numerous microbes, little is known concerning these interactions. While the environmental niche is considerably different, the free-living nematode Caenorhabditis elegans ( C. elegans ) is also found amongst a diverse microbiota, albeit on decaying organic matter. As a very well characterized model organism that has been intensively studied for several decades, C. elegans interactions with bacteria are much more deeply understood than those of their parasitic counterparts. The enormous breadth of understanding achieved by the C. elegans research community continues to inform many aspects of nematode parasitology. Here, we summarize what is known regarding parasitic nematode-bacterial interactions while comparing and contrasting this with information from work in C. elegans . This review highlights findings concerning responses to bacterial stimuli, antimicrobial peptides, and the reciprocal influences between nematodes and their environmental bacteria. Furthermore, the microbiota of nematodes as well as alterations in the intestinal microbiota of mammalian hosts by helminth infections are discussed.
Atkinson, Louise E; Miskelly, Iain R; Moffett, Christy L; McCoy, Ciaran J; Maule, Aaron G; Marks, Nikki J; Mousley, Angela
FMRFamide-like peptide (FLP) signalling systems are core to nematode neuromuscular function. Novel drug discovery efforts associated with nematode FLP/FLP receptor biology are advanced through the accumulation of basic biological data that can reveal subtle complexities within the neuropeptidergic system. This study reports the characterisation of FMRFamide-like peptide encoding gene-11 (flp-11) and FMRFamide-like peptide encoding gene-32 (flp-32), two distinct flp genes which encode the analogous peptide, AMRN(A/S)LVRFamide, in multiple nematode species - the only known example of this phenomenon within the FLPergic system of nematodes. Using bioinformatics, in situ hybridisation, immunocytochemistry and behavioural assays we show that: (i) flp-11 and -32 are distinct flp genes expressed individually or in tandem across multiple nematode species, where they encode a highly similar peptide; (ii) flp-11 does not appear to be the most widely expressed flp in Caenorhabditis elegans; (iii) in species expressing both flp-11 and flp-32, flp-11 displays a conserved, restricted expression pattern across nematode clades and lifestyles; (iv) in species expressing both flp-11 and flp-32, flp-32 expression is more widespread and less conserved than flp-11; (v) in species expressing only flp-11, the flp-11 expression profile is more similar to the flp-32 profile observed in species expressing both; and (vi) FLP-11 peptides inhibit motor function in multiple nematode species. The biological significance and evolutionary origin of flp-11 and -32 peptide duplication remains unclear despite attempts to identify a common ancestor; this may become clearer as the availability of genomic data improves. This work provides insight into the complexity of the neuropeptidergic system in nematodes, and begins to examine how nematodes may compensate for structural neuronal simplicity. From a parasite control standpoint, this work underscores the importance of basic biological data, and has
Full Text Available Introduction: Grapevine belongs to the Vitaceae family that consists of 14 genera and about 700 species. Only in the genus Vitis fruits are edible. Italy is the largest producer of grapes and Iran has the seventh position in the world from this point of view. Western Azarbaijan province comprises a high diversity of crops including wild grapes. Although, some nematodes are free living and antagonists of another soil microfauna, the other are plant parasitic agents. Most of which live in the agricultural soils where they are widely dispersed. Effectiveness of the disease management strategies are affected by the accurate identification of the plant disease causal agents and the nematodal diseases are not the exception from this rule. Therefore, for control of the diseases caused by the nematodes, it is necessary to separate the parasitic nematodes from the suspected contaminated soils and identify them. Although separation and identification of the nematodes are partly time-consuming, it is not very complicated. Some nematodes likeXiphinema, Longidorus and Ditylenchus are cosmopolitan and catastrophic nematodes in vineyards worldwide. So far no study has been performed regarding the plant parasitic nematode in vineyards of the south of Western Azerbaijan. Therefore, in this study as an introduction to the management ofthe vineyard parasitic nematodes, the dominant nematodes of the plant were identified. In the next step, investigation of nematodes bioecology, the interaction of nematodes with the other plant pathogens, their host range and their damages to the host plants would be studied. Materials and Methods: In order to identify the fauna of plant parasitic nematodes in vineyards of the south of Western Azarbaijan, during 2013-2014, 50 soil samples were collected from the rhizosphere of grapevine. The sampling was carried out from the vineyards of five grapevine growing cities including Mahabad, Bookan, Sardasht, Piranshahr and Miyandoab. The
Full Text Available Nematodes are some of the most abundant soil organisms and are an essential part of soil ecology. These organisms are used as indicator organisms and can be linked to soil health. Biological collections contain vast amounts of data, with the National Collection of Nematodes housed at the Plant Protection Research Institute, Agricultural Research Council being no different. During the digitising of the collection a number of unpublished records of plant nematodes reported from protected areas in KwaZulu-Natal were found in the South African Plant-Parasitic Nematode Survey database. A total of 222 plant nematode species belonging to 39 genera were reported from the province, with only 94 of these species reported from the protected areas and 172 and 159 species reported from uncultivated (outside the protected areas and cultivated areas, respectively. Only nine species, Criconema silvum, Criconema talanum, Helicotylenchus marethae, Ogma dracomontanum, Ogma louisi, Ogma ueckermanni, Paralongidorus deborae, Trichodorus rinae and Xiphinemella marindae were described from protected areas, whilst O. dracomontanum, P. deborae and T. rinae were subsequently also reported from other provinces. Conservation implications: A higher degree of diversity of nematodes was observed in the unprotected areas of the province. The observation suggests that nematode fauna, and by implication also other invertebrates, are not adequately protected.
Full Text Available Nematodes are some of the most abundant soil organisms and are an essential part of soil ecology. These organisms are used as indicator organisms and can be linked to soil health. Biological collections contain vast amounts of data, with the National Collection of Nematodes housed at the Plant Protection Research Institute, Agricultural Research Council being no different. During the digitising of the collection a number of unpublished records of plant nematodes reported from protected areas in KwaZulu-Natal were found in the South African Plant-Parasitic Nematode Survey database. A total of 222 plant nematode species belonging to 39 genera were reported from the province, with only 94 of these species reported from the protected areas and 172 and 159 species reported from uncultivated (outside the protected areas and cultivated areas, respectively. Only nine species, Criconema silvum, Criconema talanum, Helicotylenchus marethae, Ogma dracomontanum, Ogma louisi, Ogma ueckermanni, Paralongidorus deborae, Trichodorus rinae and Xiphinemella marindae were described from protected areas, whilst O. dracomontanum, P. deborae and T. rinae were subsequently also reported from other provinces. Conservation implications: A higher degree of diversity of nematodes was observed in the unprotected areas of the province. The observation suggests that nematode fauna, and by implication also other invertebrates, are not adequately protected.
Volkmar, K. M.
The effect of Heterodera avenae infestation on early seminal and lateral root growth was examined in four oat genotypes differing in tolerance to H. avenae. Recently emerged seminal roots were inoculated with a range of H. avenae larval densities, then transferred a hydroponic system to remove the effect of later nematode penetration on root development. Intolerance to H. avenae was assessed in terms of impairment of seminal root extension resulting in fewer primary lateral roots emerging fro...
Full Text Available Small RNA pathways act at the front line of defence against transposable elements across the Eukaryota. In animals, Piwi interacting small RNAs (piRNAs are a crucial arm of this defence. However, the evolutionary relationships among piRNAs and other small RNA pathways targeting transposable elements are poorly resolved. To address this question we sequenced small RNAs from multiple, diverse nematode species, producing the first phylum-wide analysis of how small RNA pathways evolve. Surprisingly, despite their prominence in Caenorhabditis elegans and closely related nematodes, piRNAs are absent in all other nematode lineages. We found that there are at least two evolutionarily distinct mechanisms that compensate for the absence of piRNAs, both involving RNA-dependent RNA polymerases (RdRPs. Whilst one pathway is unique to nematodes, the second involves Dicer-dependent RNA-directed DNA methylation, hitherto unknown in animals, and bears striking similarity to transposon-control mechanisms in fungi and plants. Our results highlight the rapid, context-dependent evolution of small RNA pathways and suggest piRNAs in animals may have replaced an ancient eukaryotic RNA-dependent RNA polymerase pathway to control transposable elements.
Novobilský, Adam; Mueller-Harvey, Irene; Thamsborg, Stig Milan
The use of natural plant anthelmintics was suggested as a possible alternative control of gastrointestinal nematodes (GIN) in ruminants. Direct anthelmintic effects of tannin-containing plants have already been shown in sheep and goat GIN. These anthelmintic properties are mainly associated...... with condensed tannins. In the present study, we evaluated possible in vitro effects of three tannin-containing plants against bovine GIN. Effects of Onobrychis viciifolia, Lotus pedunculatus and Lotus corniculatus condensed tannin (CT) extracts on Cooperia oncophora and Ostertagia ostertagi were determined...... (third stage larvae) was also affected by CT extracts from all three plants. In both in vitro assays, extracts with added polyvinylpolypyrrolidone, an inhibitor of tannins, generated almost the same values as the negative control; this confirms the role of CT in the anthelmintic effect of these plant...
(GIN) infection and identified the common GIN parasites in commercial goat production in. Central Uganda. .... Table 1. Prevalence of gastro-intestinal nematode parasites in goats in Central Uganda .... ILCA, Addis Ababa, Ethiopia. pp. 40-76.
Zhou, Ying; Loeza-Cabrera, Mario; Liu, Zheng; Aleman-Meza, Boanerges; Nguyen, Julie K; Jung, Sang-Kyu; Choi, Yuna; Shou, Qingyao; Butcher, Rebecca A; Zhong, Weiwei
It is crucial for animal survival to detect dangers such as predators. A good indicator of dangers is injury of conspecifics. Here we show that fluids released from injured conspecifics invoke acute avoidance in both free-living and parasitic nematodes. Caenorhabditis elegans avoids extracts from closely related nematode species but not fruit fly larvae. The worm extracts have no impact on animal lifespan, suggesting that the worm extract may function as an alarm instead of inflicting physical harm. Avoidance of the worm extract requires the function of a cGMP signaling pathway that includes the cGMP-gated channel TAX-2/TAX-4 in the amphid sensory neurons ASI and ASK. Genetic evidence indicates that the avoidance behavior is modulated by the neurotransmitters GABA and serotonin, two common targets of anxiolytic drugs. Together, these data support a model that nematodes use a nematode-specific alarm pheromone to detect conspecific injury. Copyright © 2017 by the Genetics Society of America.
The population characteristics of the nematode fauna from five replicate cores taken over four seasons at nine sites within mangroves, at three different estuaries on the south-east coast of Australia, are compared. Using cluster analysis, principal co-ordinate analysis and other statistical techniques, the variation in nematode populations is identified as arising from several sources: temperature changes between the more northerly and southerly estuaries (5%); changes in grain size and organic content of the sediment between sites (22%); changes between sites in the frequency of samples containing certain types of food, particularly associated with pools of water and surface topography (30%); stochastic changes in nematode populations within individual samples, probably caused by small scale spatial and temporal variability in food sources (35%); and seasonal changes at all the sites and estuaries (8%). The implications of this pattern of variation for the biology of the nematodes is discussed.
and respond to long- and medium-term physical, chemical and biological .... that the formation of fibrotic capsules around nematode larvae might prevent further ... capabilities and function primarily in the encapsulation of large parasitic ...
Abstract We present an updated list of terrestrial and freshwater nematodes from all regions of the Arctic, for which records of properly identified nematode species are available: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239
Deppe, U; Schierenberg, E; Cole, T; Krieg, C; Schmitt, D; Yoder, B; von Ehrenstein, G
Embryogenesis of the free-living soil nematode Caenorhabditis elegans produces a juvenile having about 550 cells at hatching. We have determined the lineages of 182 cells by tracing the divisions of individual cells in living embryos. An invariant pattern of cleavage divisions of the egg generates a set of stem cells. These stem cells are the founders of six stem cell lineages. Each lineage has its own clock--i.e., an autonomous rhythm of synchronous cell divisions. The rhythms are maintained in spite of extensive cellular rearrangement. The rate and the orientation of the cell divisions of the cell lineages are essentially invariant among individuals. Thus, the destiny of cells seems to depend primarily on their lineage history. The anterior position of the site of origin of the stem cells in the egg relates to the rate of the cell cycle clock, suggesting intracellular preprogramming of the uncleaved egg. We used a technique that allows normal embryogenesis, from the fertilized egg to hatching, outside the parent under a cover glass. Embryogenesis was followed microscopically with Nomarski interference optics and high-resolution video recording.
Gang, Spencer S.; Castelletto, Michelle L.
Parasitic nematodes infect over 1 billion people worldwide and cause some of the most common neglected tropical diseases. Despite their prevalence, our understanding of the biology of parasitic nematodes has been limited by the lack of tools for genetic intervention. In particular, it has not yet been possible to generate targeted gene disruptions and mutant phenotypes in any parasitic nematode. Here, we report the development of a method for introducing CRISPR-Cas9-mediated gene disruptions in the human-parasitic threadworm Strongyloides stercoralis. We disrupted the S. stercoralis twitchin gene unc-22, resulting in nematodes with severe motility defects. Ss-unc-22 mutations were resolved by homology-directed repair when a repair template was provided. Omission of a repair template resulted in deletions at the target locus. Ss-unc-22 mutations were heritable; we passed Ss-unc-22 mutants through a host and successfully recovered mutant progeny. Using a similar approach, we also disrupted the unc-22 gene of the rat-parasitic nematode Strongyloides ratti. Our results demonstrate the applicability of CRISPR-Cas9 to parasitic nematodes, and thereby enable future studies of gene function in these medically relevant but previously genetically intractable parasites. PMID:29016680
Paula Nogueira Curi
Full Text Available ABSTRACT: In recent years "redness" has increasingly appeared in strawberry plants with leaves taking on a reddish color. No causal agent has been associated with plants. Since strawberries presented problems due to the incidence of nematodes, the purpose of this study was to look at the relationship between production, resistance to the Meloidogyne hapla nematode and the "redness" symptom in strawberry cultivars. Two experiments were performed, both with the 'Camino Real', 'Festival', 'Oso Grande', 'Albion' and 'Camarosa' cultivars. The first experiment was performed in the field, where the following were evaluated: strawberry production, fruit quality, macro and micronutrient contents in fruit and leaves, percentage of plant survival, incidence of nematodes, quantity of eggs in the roots and juveniles in the soil, and the incidence of Botrytis cinerea . In the second experiment, the strawberries were transplanted into pots and filled with pinus bark-based commercial substrate. Half the pots were inocculated with Meloidogyne hapla . Cultivars presented differences in fruit production and also in the incidence of "redness". Lowest performance in production was related to the high incidence of the nematode Meloidogyne hapla. 'Oso Grande' and 'Albion' presented nematode-resistant behavior. It was possible find a relationship between the incidence of the Meloidogyne hapla nematode, and the incidence of "redness" only 'Camino Real' cultivar.
Radochova, Petra; Frouz, Jan
Since the 20th century, the distribution of European heathlands rapidly decreased due to agricultural intensification, heavy use of artificial fertilizers or acidification (Aerts & Heil, 1993). Therefore, various attempts of heathland restoration are under way in these days. Analysis of nematode community composition can be one of the tools suitable for succession evaluation (Ferris et al., 2001). In 2011, 2013 and 2014, soil samples were collected from heathland restoration experiment (launched in 2011) where different restoration methods were applied in a 3 × 3 factorial experiment; existing heathlands were also sampled to identify the target community both in dry and wet heathland. A total of 60 samples of extracted nematodes were analysed for absolute abundance, trophic groups, and genera dominance. Various indices were calculated to describe the nematode community. We were able to prove faster development of wet heathlands towards the target community. However, because of large data variability, there was no significant difference between treatments. Development of wet and dry heathlands differed also in increased proportion of omniphagous nematodes in 2013 and predators in 2014 in dry heathlands. After three years of heathland restoration, nematode community has not yet reached parameters of the target community. References Aerts, R., Heil, G. W., 1993. Heathlands: patterns and processes in a changing environment, 1st ed, Geobotany: 20. Springer Netherlands, Dordrecht, p. 229. Ferris, H., Bongers, T., De Goede, R. G. M., 2001. A framework for soil food web diagnostics: Extension of the nematode faunal analysis oncept. Appl. Soil Ecol. 18, 13-29.
Zamanian, Mostafa; Cook, Daniel E; Zdraljevic, Stefan; Brady, Shannon C; Lee, Daehan; Lee, Junho; Andersen, Erik C
Parasitic nematodes impose a debilitating health and economic burden across much of the world. Nematode resistance to anthelmintic drugs threatens parasite control efforts in both human and veterinary medicine. Despite this threat, the genetic landscape of potential resistance mechanisms to these critical drugs remains largely unexplored. Here, we exploit natural variation in the model nematodes Caenorhabditis elegans and Caenorhabditis briggsae to discover quantitative trait loci (QTL) that control sensitivity to benzimidazoles widely used in human and animal medicine. High-throughput phenotyping of albendazole, fenbendazole, mebendazole, and thiabendazole responses in panels of recombinant lines led to the discovery of over 15 QTL in C. elegans and four QTL in C. briggsae associated with divergent responses to these anthelmintics. Many of these QTL are conserved across benzimidazole derivatives, but others show drug and dose specificity. We used near-isogenic lines to recapitulate and narrow the C. elegans albendazole QTL of largest effect and identified candidate variants correlated with the resistance phenotype. These QTL do not overlap with known benzimidazole target resistance genes from parasitic nematodes and present specific new leads for the discovery of novel mechanisms of nematode benzimidazole resistance. Analyses of orthologous genes reveal conservation of candidate benzimidazole resistance genes in medically important parasitic nematodes. These data provide a basis for extending these approaches to other anthelmintic drug classes and a pathway towards validating new markers for anthelmintic resistance that can be deployed to improve parasite disease control.
Johnigk, S-A; Ecke, F; Poehling, M; Ehlers, R-U
Heterorhabditis bacteriophora is used in biological control of soil-borne insect pests in horticulture and turf. Mass production is carried out in monoxenic liquid cultures pre-incubated with the symbiont of the nematodes, the bacterium Photorhabdus luminescens, before nematode dauer juveniles (DJ) are inoculated. As a response to bacterial food signals, the DJ recover from the developmentally arrested dauer stage, grow to adults and produce DJ offspring. Variable DJ recovery after inoculation into cultures of P. luminescens often causes process failure due to low numbers of adult nematodes in the medium. In order to enhance DJ recovery, improve nematode population management and increase yields, the optimal timing for DJ inoculation was sought. The process parameter pH and respiration quotient (RQ) were recorded in order to test whether changes can be used to identify the best moment for DJ inoculation. When DJ were inoculated during the lag and early logarithmic growth phases of P. luminescens cultures, DJ recovery was low and almost no nematode reproduction was obtained. High populations of P. luminescens phase variants were recorded. Recovery and yields increased when DJ were inoculated during the latter log phase during which the RQ dropped to values <0.8 and the pH reached a maximum. The highest DJ recovery and yields were observed in cultures that were inoculated during the late stationary growth phase. This period started with the increase of the pH after its distinct minimum at pH <8.0. Thus optimal timing for DJ inoculation can be defined through monitoring of the pH in the P. luminescens culture.
Bohlmann, Holger; Sobczak, Miroslaw
Plant parasitic cyst nematodes (genera Heterodera and Globodera) are serious pests for many crops. They enter the host roots as migratory second stage juveniles (J2) and migrate intracellularly toward the vascular cylinder using their stylet and a set of cell wall degrading enzymes produced in the pharyngeal glands. They select an initial syncytial cell (ISC) within the vascular cylinder or inner cortex layers to induce the formation of a multicellular feeding site called a syncytium, which is the only source of nutrients for the parasite during its entire life. A syncytium can consist of more than hundred cells whose protoplasts are fused together through local cell wall dissolutions. While the nematode produces a cocktail of cell wall degrading and modifying enzymes during migration through the root, the cell wall degradations occurring during syncytium development are due to the plants own cell wall modifying and degrading proteins. The outer syncytial cell wall thickens to withstand the increasing osmotic pressure inside the syncytium. Furthermore, pronounced cell wall ingrowths can be formed on the outer syncytial wall at the interface with xylem vessels. They increase the surface of the symplast-apoplast interface, thus enhancing nutrient uptake into the syncytium. Processes of cell wall degradation, synthesis and modification in the syncytium are facilitated by a variety of plant proteins and enzymes including expansins, glucanases, pectate lyases and cellulose synthases, which are produced inside the syncytium or in cells surrounding the syncytium.
Full Text Available Plant parasitic cyst nematodes (genera Heterodera and Globodera are serious pests for many crops. They enter the host roots as migratory second stage juveniles (J2 and migrate intracellularly towards the vascular cylinder using their stylet and a set of cell wall degrading enzymes produced in the pharyngeal glands. They select an initial syncytial cell (ISC within the vascular cylinder or inner cortex layers to induce the formation of a multicellular feeding site called a syncytium, which is the only source of nutrients for the parasite during its entire life. A syncytium can consist of more than hundred cells whose protoplasts are fused together through local cell wall dissolutions. While the nematode produces a cocktail of cell wall degrading and modifying enzymes during migration through the root, the cell wall degradations occurring during syncytium development are due to the plants own cell wall modifying and degrading proteins. The outer syncytial cell wall thickens to withstand the increasing osmotic pressure inside the syncytium. Furthermore, pronounced cell wall ingrowths can be formed on the outer syncytial wall at the interface with xylem vessels. They increase the surface of the symplast-apoplast interface, thus enhancing nutrient uptake into the syncytium. Processes of cell wall degradation, synthesis and modification in the syncytium are facilitated by a variety of plant proteins and enzymes including expansins, glucanases, pectate lyases and cellulose synthases, which are produced inside the syncytium or in cells surrounding the syncytium.
Madsen, Mette Vestergård
rhizosphere; nitrogen and phosphorus fertilisation; nematode assemblages; plant parasites; barley......rhizosphere; nitrogen and phosphorus fertilisation; nematode assemblages; plant parasites; barley...
Sultana, V.; Haque, S.E.; Baloch, G.N.; Ara, J.
Application of seaweed as soil amendment for the control of soil borne plant diseases has increased in recent years due to their environment friendly role. In screen house study, a red seaweed Solieria robusta used as soil amendment showed better suppressive effect on root rotting fungus Fusarium solani than Topsin-M, a fungicide, but was found less effective than Topsin-M against Macrophomina phaseolina and Rhizoctonia solani on soybean. Solieria robusta showed similar suppressive effect on root knot nematode as did carbofuran, a nematicide. Seaweed showed slightly better effect on plant growth than urea or potash by producing taller plants, better root length and number of flowers per plant. However, mixed application of S.robusta and Topsin-M produced greater number of flowers per plant and tallest plants. (author)
Entomopathogenic nematodes in the families Heterorhabditidae and Steinernematidae have considerable potential as biological control agents of soil-inhabiting insect pests. Attributes making these nematodes ideal biological control agents include their broad host range, high virulence,
Communities of soil nematodes impact ecosystem functions, including plant growth, decomposition, and nutrient cycling, all of which are vital processes in agriculture. We used complementary morphological and DNA metabarcoding analyses to characterize soil nematode communities in three cropping syste...
N. Mohilal; M. Pramodini; L. Bina
In the present study soil samples were collected from Lokchao Yangoupokpi Wildlife Sanctuary to investigate about what nematode species are associated with different plant hosts. This study shows rich nematode diversity in the sanctuary.
Full Text Available In the present study soil samples were collected from Lokchao Yangoupokpi Wildlife Sanctuary to investigate about what nematode species are associated with different plant hosts. This study shows rich nematode diversity in the sanctuary.
Georgis, Ramon; Mullens, Bradley A.; Meyer, Jeffery A.
Survival, infectivity, and movement of three insect parasitic nematodes (Steinernema feltiae All strain, S. bibionis SN strain, and Heterorhabditis heliothidis NC strain) in poultry manure were tested under laboratory conditions. The majority (70-100%) of the nematodes died within 18 hours after exposure to the manure. Nematodes exposed to manure slurry for 6 hours killed at least 95% of the house fly larvae, Musca domestica, but nematodes exposed for 12 hours achieved less than 40% larval mo...
Jones, J T; Reavy, B; Smant, G; Prior, A E
We report the cloning and characterisation of full-length DNAs complementary to RNA (cDNAs) encoding two glutathione peroxidases (GpXs) from a plant parasitic nematode, the potato cyst nematode (PCN) Globodera rostochiensis. One protein has a functional signal peptide that targets the protein for secretion from animal cells while the other is predicted to be intracellular. Both genes are expressed in all parasite stages tested. The mRNA encoding the intracellular GpX is present throughout the nematode second stage juvenile and is particularly abundant in metabolically active tissues including the genital primordia. The mRNA encoding the secreted GpX is restricted to the hypodermis, the outermost cellular layer of the nematode, a location from which it is likely to be secreted to the parasite surface. Biochemical studies confirmed the secreted protein as a functional GpX and showed that, like secreted GpXs of other parasitic nematodes, it does not metabolise hydrogen peroxide but has a preference for larger hydroperoxide substrates. The intracellular protein is likely to have a role in metabolism of active oxygen species derived from internal body metabolism while the secreted protein may protect the parasite from host defences. Other functional roles for this protein are discussed.
Full Text Available In the three decades since the FMRFamide peptide was isolated from the mollusk Macrocallista nimbosa, structurally similar peptides sharing a C-terminal RFamide motif have been identified across the animal kingdom. FMRFamide-like peptides (FLPs represent the largest known family of neuropeptides in invertebrates. In the phylum Nematoda, at least 32 flp genes are classified, making the FLP system of nematodes unusually complex. The diversity of the nematode FLP complement is most extensively mapped in Caenorhabditis elegans, where over 70 FLPs have been predicted. FLPs have shown to be expressed in the majority of the 302 C. elegans neurons including interneurons, sensory and motor neurons. The vast expression of FLPs is reflected in the broad functional repertoire of nematode FLP signaling, including neuroendocrine and neuromodulatory effects on locomotory activity, reproduction, feeding, and behavior. In contrast to the many identified nematode FLPs, only few peptides have been assigned a receptor and there is the need to clarify the pathway components and working mechanisms of the FLP signaling network. Here, we review the diversity, distribution, and functions of FLPs in nematodes.
Muhammad A. Ali
Full Text Available Nematodes are omnipresent in nature including many species which are parasitic to plants and cause enormous economic losses in various crops. During the process of parasitism, sedentary phytonematodes use their stylet to secrete effector proteins into the plant cells to induce the development of specialized feeding structures. These effectors are used by the nematodes to develop compatible interactions with plants, partly by mimicking the expression of host genes. Intensive research is going on to investigate the molecular function of these effector proteins in the plants. In this review, we have summarized which physiological and molecular changes occur when endoparasitic nematodes invade the plant roots and how they develop a successful interaction with plants using the effector proteins. We have also mentioned the host genes which are induced by the nematodes for a compatible interaction. Additionally, we discuss how nematodes modulate the reactive oxygen species (ROS and RNA silencing pathways in addition to post-translational modifications in their own favor for successful parasitism in plants.
Peña, Jennifer M; Carrillo, Mayra A; Hallem, Elissa A
Entomopathogenic nematodes (EPNs) in the genera Heterorhabditis and Steinernema are lethal parasites of insects that are of interest as models for understanding parasite-host interactions and as biocontrol agents for insect pests. EPNs harbor a bacterial endosymbiont in their gut that assists in insect killing. EPNs are capable of infecting and killing a wide range of insects, yet how the nematodes and their bacterial endosymbionts interact with the insect immune system is poorly understood. Here, we develop a versatile model system for understanding the insect immune response to parasitic nematode infection that consists of seven species of EPNs as model parasites and five species of Drosophila fruit flies as model hosts. We show that the EPN Steinernema carpocapsae, which is widely used for insect control, is capable of infecting and killing D. melanogaster larvae. S. carpocapsae is associated with the bacterium Xenorhabdus nematophila, and we show that X. nematophila induces expression of a subset of antimicrobial peptide genes and suppresses the melanization response to the nematode. We further show that EPNs vary in their virulence toward D. melanogaster and that Drosophila species vary in their susceptibilities to EPN infection. Differences in virulence among different EPN-host combinations result from differences in both rates of infection and rates of postinfection survival. Our results establish a powerful model system for understanding mechanisms of host-parasite interactions and the insect immune response to parasitic nematode infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Person, Francoise; Brun, J.
Chemical mutagens as EMS, acriflavine, acridine, colchicine, nitrous acide and physical mutagens, such as X rays, have been used on the gonochoric mycophagous Nematode Aphelenchoides composticola. They show a nematicid activity due, to their toxicity on treated Nematodes and to the induction of lethal mutations affecting particularly early stages of gametogenesis. They produce abnormal strains dwarfs or giants (up to 25% of the population). Concentrations of chemical mutagens varying from 0.2 to 0.5% correspond to the optimal production of abnormalities. Similar results were obtained by irradiation near to 2000r. The action of the mutagens shows some differences: EMS and X rays generally produce dwarfs, whereas acriflavine, acridine, colchicine or nitrous acid induced only giants. Abnormal strains appear: in the F 1 , generation by X rays or acridine treatments; in the F 2 or F 3 generation by acriflavine, colchicine, nitrous acid or EMS action. The abnormal strains could be either variants or mutants and from these we select: four dwarfs B, C, D, E, induced by EMS 0.5% for 24 hours appearing in the F 3 generation; or dwarf F induced by irradiation of 1500r appearing in the F 1 generation. All these selected mutants are autosomal recessive single factors D and C controlled by two alleles of the some locus [fr
Full Text Available 10 years of joint efforts in research and development have led to a nematode-based biological control solution for one of the most destructive maize pests, the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae. Commercially mass-produced Heterorhabditis species of beneficial entomopathogenic nematodes are ready to use. They can be applied into the soil during sowing of maize for controlling the subsequently hatching larvae of D. virgifera virgifera thus preventing root feeding and damage to maize. Policy bodies, decision makers and farmers are advised to consider biological control as one of the alternatives to synthetic pesticides in maize production, and according to the EC Directive on the sustainable use of pesticides and implementation of integrated pest management.
Screenhouse experiments were conducted to test the efficacy of cowdung and urine separately and in combination in the control of root-knot nematode of tomato. Equal quantities of cowdung, urine and their mixture were separately made up to one litre with autoclaved soil. Two weeks old seedlings of tomato raised in ...
Janse, J.; Slooten, van M.A.; Wurff, van der A.W.G.
During 5 years, Wageningen UR Greenhouse Horticulture did research to find a rootstock with high resistance against the most important root knot nematodes or Meloidogyne species in greenhouses in the Netherlands, M. incognita, M. hapla and M. javanica. Rootstocks should combine resistance with good
AZADIRACHTA INDICA) ... yield of treated tomato plants. Key Words: Neem, Nematicidal Properties, Root Knot Nematode, Tomato. .... Means with the same letter in the same column do not differ significantly at P = 0.05 according to Duncan`s multiple ...
Beginning in 1998, a bioassay using second-stage juveniles (J2) from a greenhouse (GH) population of the root-knot nematode Meloidogyne arenaria (Ma) was used to monitor endospore densities of the bacterium Pasteuria penetrans, which was parasitizing Ma in a long-term rotation study (begun in 1991)....
The endospore-forming bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes (Meloidogyne spp.). This bacterium is commonly found in agricultural soils and has been associated with suppression of Meloidogyne spp. In a field site naturally infested with both P. penetrans and M...
We hypothesized that root exudates would influence the spore attachment of Pasteuria penetrans to root-knot nematodes (Meloidogyne arenaria). An experiment was carried out using a factorial arrangement of two single spore (SS) lines cultured from P. penetrans and three single egg mass(SEM)lines cult...
The aim of this study was to examine genotypic variation and virulence characteristics of a population of bacterial parasite of root-knot nematode (RKN), Pasteuria penetrans, isolated from Florida. Six single spore lines (ssp), 16ssp, 17ssp, 18ssp, 25ssp, 26ssp, and 30ssp were generated by infecting...
Deficit irrigation is considered to be an important approach for crop cultivation in dry regions where water resources are scarce. Deficit irrigation can be used also to decrease the level of infections by some moisturedependent plant pests and diseases such as root-knot nematode disease. Therefore, deficit irrigation at levels ...
Two field experiments were conducted using a common tomato cultivar (GS12) to assess the effect of deficit irrigation (DI) regimes on tomato growth performance, and on root-knot nematode Meloidogyne javanica galling and abundance. Irrigation treatments consisted of five irrigation regimes: 20%, 40%, 60%, 80% and ...
Grafting has gained popularity as a method to manage plant diseases previously controlled by soil fumigation with methyl bromide. Some of the most significant soilborne pest problems for which resistant rootstocks may be beneficial include root-knot nematodes, Verticillium wilt, and southern blight....
Southern root-knot nematodes (Meloidogyne incognita) are a pest on many economically important row crop and vegetable species and management relies on chemicals, plant resistance, and cultural practices such as crop rotation. Little is known about the inheritance of resistance to M. incognita or the...
Steam and soil solarization were investigated for control of the root-knot nematode Meloidogyne arenaria in two years of field trials on a commercial flower farm in Florida. The objective was to determine if pre-plant steam treatments in combination with solarization, or solarization alone effective...
Steam and soil solarization were investigated for control of the root-knot nematode Meloidogyne arenaria in two years of field trials on a commercial flower farm in Florida. The objective was to determine if pre-plant steam treatments in combination with solarization, or solarization alone effective...
Efficacy of Pleurotus tuberregium, Neem-leaf ash, carbofuram and combination of the three above were tested in the control of root-knot nematode (Meloidogyne incognita) on Hausa potato. In the green house, twenty-five polythene bags were filled with 10kg of steam-sterilized sandy loam soil and Hausa potato seedlings ...
Field tests were conducted to determine if differences in response to nematicide application (i.e., root-knot nematode (RKN) population levels, cotton yield, and profitability) occurred among RKN management zones (MZ). The MZ were delineated using variables related to soil texture, including appare...
readily degraded ·'in soil, and has no harmfull effects on soil processes. (ICI,. 19 8 7). The present investigation was therefore carried out to explore the nematicidal p r o p e .r t i e s o £ lambdacyhalothrin against the ' root knot nematode M. incognita on soybeans. The intensive cultivation of soybean ·has often allowed the ...
Carneiro, R.M.D.G.; Lourdes Mendes, de M.; Almeida, M.R.A.; Santos, Dos M.F.A.; Gomes, A.C.M.M.; Karssen, G.
A root-knot nematode parasitising yakon (Polymia sonchifolia) in São Paulo State, Brazil, is identified as Meloidogyne inornata. The species is redescribed from this material and compared with the original description of M. inornata. The female perineal patterns have a distinct, high, dorsal arch
Available online at http://ajol.info/index.php/njbas/index. Nigerian Journal of Basic and Applied Science (2010), 18(2): 272-276. ISSN 0794-5698. Effect of Mahogany (Khaya senegalensis L) Leaf Extract on Root-Knot Nematode of. Tomatoes (Lycopersicum esculentum L.) B. Liman. 1. , M. Ibrahim. 1. , N.T. Ibrahim. 1.
Biological control against the root-knot nematode, Meloidogyne incognita was proven to occur in tomato, Solanum lycopersicom, soil-drenched with different isolates of Trichoderma harzianum and a commercial suspension of Serratia marcescens (Nemaless). The potential of such biocontrol agents to trigger plant defense ...
Thoden, T.C.; Korthals, G.W.; Visser, J.H.M.; Gastel-Topper, van A.W.W.
For several years, a new species of root-knot nematode, Meloidogyne minor, has been reported from parts of The Netherlands, Belgium, UK and Ireland. So far, this species causes most problems on golf courses but has also been reported from a potato field in Zeijerveld (The Netherlands) where it
Tomato is one of the crops in which genetic resistance has specially been effective against root-knot nematodes. In this study, molecular screening was done on some tomato germplasm to detect markers for the gene that confers resistance (Mi) with specific primer (Mi23/F//Mi23/R). The cultivars; VFNT, FLA 505-BL 1172, ...
The prohibitive cost is another limitation in the use of ... reported to be effective in the management of root-knot nematodes in crops like okra (Adekunle, ..... fertility, poor management practices, prevalence of pests and diseases, poorly organized seed .... Realizing that the profit maximizing levels of variable inputs (Xi*) would ...
Background: Plant parasitic nematodes (PPNs) are obligate parasites that feed on the roots of living host plants. Often, these nematodes can lay hundreds of eggs, each capable of surviving in the soil for as long as 12 years. When it comes to wreaking havoc on agricultural yield, few nematodes can c...
.... APHIS-2012-0079] Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY... nematode regulations by removing areas in Livingston and Steuben Counties in New York from the list of... nematode, and we determined that regulation of these areas was no longer necessary. As a result of that...
... 7 Agriculture 5 2010-01-01 2010-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...
...-0079] Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY AGENCY: Animal... are amending the golden nematode regulations by removing areas in Livingston and Steuben Counties in... areas in these two counties are free of golden nematode, and we have determined that regulation of these...
Some phytoparasitic nematodes have the ability to infect and reproduce on plants that are normally considered resistant to nematode infection. Such nematodes are referred to as virulent and the mechanisms they use to evade or suppress host plant defenses are not well understood. Here, we report the ...
Full Text Available The cyst nematode Heterodera schachtii infects roots of Arabidopsis plants and establishes feeding sites called syncytia, which are the only nutrient source for nematodes. Development of syncytia is accompanied by changes in cell wall structures including the development of cell wall ingrowths. UDP-glucuronic acid is a precursor of several cell wall polysaccharides and can be produced by UDP-glucose dehydrogenase through oxidation of UDP-glucose. Four genes in Arabidopsis encode this enzyme. Promoter::GUS analysis revealed that UGD2 and UGD3 were expressed in syncytia as early as 1 dpi while expression of UGD1 and UGD4 could only be detected starting at 2 dpi. Infection assays showed no differences between Δugd1 and Δugd4 single mutants and wild type plants concerning numbers of males and females and the size of syncytia and cysts. On single mutants of Δugd2 and Δugd3, however, less and smaller females, and smaller syncytia formed compared to wild type plants. The double mutant ΔΔugd23 had a stronger effect than the single mutants. These data indicate that UGD2 and UGD3 but not UGD1 and UGD4 are important for syncytium development. We therefore studied the ultrastructure of syncytia in the ΔΔugd23 double mutant. Syncytia contained an electron translucent cytoplasm with degenerated cellular organelles and numerous small vacuoles instead of the dense cytoplasm as in syncytia developing in wild type roots. Typical cell wall ingrowths were missing in the ΔΔugd23 double mutant. Therefore we conclude that UGD2 and UGD3 are needed for the production of cell wall ingrowths in syncytia and that their lack leads to a reduced host suitability for H. schachtii resulting in smaller syncytia, lower number of developing nematodes, and smaller females.
Chen, Z X; Dickson, D W
Pasteuria penetrans is a mycelial, endospore-forming, bacterial parasite that has shown great potential as a biological control agent of root-knot nematodes. Considerable progress has been made during the last 10 years in understanding its biology and importance as an agent capable of effectively suppressing root-knot nematodes in field soil. The objective of this review is to summarize the current knowledge of the biology, ecology, and biological control potential of P. penetrans and other Pasteuria members. Pasteuria spp. are distributed worldwide and have been reported from 323 nematode species belonging to 116 genera of free-living, predatory, plant-parasitic, and entomopathogenic nematodes. Artificial cultivation of P. penetrans has met with limited success; large-scale production of endospores depends on in vivo cultivation. Temperature affects endospore attachment, germination, pathogenesis, and completion of the life cycle in the nematode pseudocoelom. The biological control potential of Pasteuria spp. have been demonstrated on 20 crops; host nematodes include Belonolaimus longicaudatus, Heterodera spp., Meloidogyne spp., and Xiphinema diversicaudatum. Pasteuria penetrans plays an important role in some suppressive soils. The efficacy of the bacterium as a biological control agent has been examined. Approximately 100,000 endospores/g of soil provided immediate control of the peanut root-knot nematode, whereas 1,000 and 5,000 endospores/g of soil each amplified in the host nematode and became suppressive after 3 years.
Colonization of plants by particular endophytic fungi can provide plants with improved defenses toward nematodes. Evidently, such endophytes can be important in developing more sustainable agricultural practices. The mechanisms playing a role in this quantitative antagonism are poorly understood but most likely multifactorial. This knowledge gap obstructs the progress regarding the development of endophytes or endophyte-derived constituents into biocontrol agents. In part, this may be caused by the fact that endophytic fungi form a rather heterogeneous group. By combining the knowledge of the currently characterized antagonistic endophytic fungi and their effects on nematode behavior and biology with the knowledge of microbial competition and induced plant defenses, the various mechanisms by which this nematode antagonism operates or may operate are discussed. Now that new technologies are becoming available and more accessible, the currently unresolved mechanisms can be studied in greater detail than ever before.
Butcher, Rebecca A
The existence of small-molecule signals that influence development in Caenorhabditis elegans has been known for several decades, but only in recent years have the chemical structures of several of these signals been established. The identification of these signals has enabled connections to be made between these small molecules and fundamental signaling pathways in C. elegans that influence not only development but also metabolism, fertility, and lifespan. Spurred by these important discoveries and aided by recent advances in comparative metabolomics and NMR spectroscopy, the field of nematode chemistry has the potential to expand dramatically in the coming years. This Perspective will focus on small-molecule pheromones and hormones that influence developmental events in the nematode life cycle (ascarosides, dafachronic acids, and nemamides), will cover more recent work regarding the biosynthesis of these signals, and will explore how the discovery of these signals is transforming our understanding of nematode development and physiology.
Dorota L Porazinska
Full Text Available Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates, but not for microscopic organisms (e.g. nematodes. Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1 nematode communities were unique without even a single common species between the two rainforests, 2 nematode communities were unique among habitats in both rainforests, 3 total species richness was 300% more in the tropical than in the temperate rainforest, 4 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5 more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats and large (rainforests spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota.
Porazinska, Dorota L.; Giblin-Davis, Robin M.; Powers, Thomas O.; Thomas, W. Kelley
Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates), but not for microscopic organisms (e.g. nematodes). Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy) of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica) using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1) nematode communities were unique without even a single common species between the two rainforests, 2) nematode communities were unique among habitats in both rainforests, 3) total species richness was 300% more in the tropical than in the temperate rainforest, 4) 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5) more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats) and large (rainforests) spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota. PMID:22984536
Peng, Shuang; Yan, Shuzhen; Chen, Shuanglin
Plant-parasite nematode is one of the most important pathogens in plant. Our objective is to screen endophytic bacteria against plant-parasitic nematodes from plant. Endophytic bacteria were isolated and screened by testing their metabolite against Bursaphelenchus xylophilus in vitro. Those strains inhibiting B. xylophilus were selected to culture in liquid medium and fermentation conditions were optimized by orthogonal test. The stability of the antinematode substances was evaluated by various. In addition, four strains were identified by 16SrDNA sequence analysis. In total 13 strains of endophytic bacteria secreting antinematode metabolite were isolated from 6 species of plant. The supernatant of the fermentation broth of these endophytic bacteria gave 100% mortality of nematodes after treated as the follows: 1 ml each was mixed with 0.2 ml of the suspension of nematodes (2000 nematodes/ml) then incubated at 250C for 24 h, some of which could led to leakage or dissolution of nematodes. Among them, four strains, BCM2, SZ5, CCM7 and DP1, showed stronger activity than others. The supernatants diluted three times also gave not less than 95% mortality after 24 h treatment, and those from DP1 and SZ5 even gave 100% mortality. The fermentation conditions of the four strains were optimized and the antinematode activity grew up four times after optimization. The antinematode substances of these strains were found stable when treated with protease or heating or stored at 4 degrees C after 100 days, while instable when treated with acid or alkali. DP1 and CCM7 were identified to be Bacillus subtilis, while SZ5 and BCM2 to be Bacillus cereus. Endophytic bacteria secreting antinematode metabolite were found in economic crops. The metabolite of some strains showed strong and stable antinematode activity. Our results indicate the real potential of biocontrol by endophytic bacteria.