The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Vivian C. Blok - One of the best experts on this subject based on the ideXlab platform.

  • consistent action of two partially effective loci conferring resistance to Globodera pallida pa2 3 across multiple nematode field populations
    Plant Pathology, 2017
    Co-Authors: Vivian C. Blok, B Rigney, Denis Griffin, E Dalton, Dan Milbourne
    Abstract:

    The potato cyst nematodes (PCN) Globodera rostochiensis and Globodera pallida are significant pests of potatoes worldwide. The most effective control methods are crop rotation and the deployment of resistant varieties. Complete resistance to G. rostochiensis based on a single resistance gene has successfully been integrated into many varieties. However, resistance to G. pallida has not been as successful to date, with current varieties only exhibiting partial resistance. Combining partially effective quantitative trait loci (QTLs) for resistance can increase the strength and breadth of the resistance. An additive effect on resistance has previously been demonstrated on combining two QTLs from Solanum tuberosum subsp. andigena (GpaIVsadg) and Solanum vernei (Gpa5). However, populations of G. pallida can be quite divergent and it was unclear whether the relative effects of the individual QTLs and the combined additive effect would be consistent across different G. pallida Pa2/3 populations. Using a mapping population segregating for both QTLs, the effect of the QTLs individually and combined was examined on four UK-derived field populations of G. pallida pathotype Pa2/3, and the relative effects of the individual QTLs and the additive effect of the combination found to be consistent across all populations.

  • Activation of hatching in diapaused and quiescent Globodera pallida
    2016
    Co-Authors: Juan E. Palomares-rius, John T Jones, Peter J. Cock, Pablo Castillo, Vivian C. Blok
    Abstract:

    The potato cyst nematodes (PCN) Globodera pallida and G. rostochiensis are major pests of potatoes. The G. pallida (and G. rostochiensis) life cycle includes both diapause and quiescent stages. Nematodes in dormancy (diapause or quiescent) are adapted for long-term survival and are more resistant to nematicides. This study analysed the mechanisms underlying diapause and quiescence. The effects of several compounds (8Br-cGMP, oxotremorine and atropine) on the activation of hatching were studied. The measurements of some morphometric parameters in diapaused and quiescent eggs after exposure to PRD revealed differences in dorsal gland length, subventral gland length and dorsal gland nucleolus. In addition, the expression of 2 effectors (IVg9 and cellulase) was not induced in diapaused eggs in water or PRD, while expression was slightly induced in quiescent eggs. Finally, we performed a comparative study to identify orthologues of C. elegans diapause related genes in plant-parasitic nematodes (G. pallida, Meloidogyne incognita, M. hapla and Bursaphelenchus xylophilus). This analysis suggested that it was not possible to identify G. pallida orthologues of the majority of C. elegans genes involved in the control of dauer formation. All these data suggest that G. pallida may use different mechanisms to C. elegans in regulating the survival stage. Key words: hatching, cGMP, muscarinic pathway, potato cyst nematodes, root diffusate

  • gene expression changes in diapause or quiescent potato cyst nematode Globodera pallida eggs after hydration or exposure to tomato root diffusate
    PeerJ, 2016
    Co-Authors: Pete E. Hedley, Peter J. A. Cock, Jenny Morris, John T Jones, Juan E Palomaresrius, Vivian C. Blok
    Abstract:

    Plant-parasitic nematodes (PPN) need to be adapted to survive in the absence of a suitable host or in hostile environmental conditions. Various forms of developmental arrest including hatching inhibition and dauer stages are used by PPN in order to survive these conditions and spread to other areas. Potato cyst nematodes (PCN) (Globodera pallida and G. rostochiensis) are frequently in an anhydrobiotic state, with unhatched nematode persisting for extended periods of time inside the cyst in the absence of the host. This paper shows fundamental changes in the response of quiescent and diapaused eggs of G. pallida to hydration and following exposure to tomato root diffusate (RD) using microarray gene expression analysis encompassing a broad set of genes. For the quiescent eggs, 547 genes showed differential expression following hydration vs. hydratation and RD (H-RD) treatment whereas 708 genes showed differential regulation for the diapaused eggs following these treatments. The comparison between hydrated quiescent and diapaused eggs showed marked differences, with 2,380 genes that were differentially regulated compared with 987 genes following H-RD. Hydrated quiescent and diapaused eggs were markedly different indicating differences in adaptation for long-term survival. Transport activity is highly up-regulated following H-RD and few genes were coincident between both kinds of eggs. With the quiescent eggs, the majority of genes were related to ion transport (mainly sodium), while the diapaused eggs showed a major diversity of transporters (amino acid transport, ion transport, acetylcholine or other molecules).

  • genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida
    BMC Genomics, 2014
    Co-Authors: Vivian C. Blok, Peter J. A. Cock, Peter Thorpe, Sophie Mantelin, Mirela C Coke, Sebastian Evesvan Den Akker, Elena A Guzeeva, Catherine J Lilley
    Abstract:

    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.

  • activation of hatching in diapaused and quiescent Globodera pallida
    Parasitology, 2013
    Co-Authors: Juan E Palomaresrius, John T Jones, Peter J. A. Cock, Pablo Castillo, Vivian C. Blok
    Abstract:

    The potato cyst nematodes (PCN) Globodera pallida and G. rostochiensis are major pests of potatoes. The G. pallida (and G. rostochiensis) life cycle includes both diapause and quiescent stages. Nematodes in dormancy (diapause or quiescent) are adapted for long-term survival and are more resistant to nematicides. This study analysed the mechanisms underlying diapause and quiescence. The effects of several compounds (8Br-cGMP, oxotremorine and atropine) on the activation of hatching were studied. The measurements of some morphometric parameters in diapaused and quiescent eggs after exposure to PRD revealed differences in dorsal gland length, subventral gland length and dorsal gland nucleolus. In addition, the expression of 2 effectors (IVg9 and cellulase) was not induced in diapaused eggs in water or PRD, while expression was slightly induced in quiescent eggs. Finally, we performed a comparative study to identify orthologues of C. elegans diapause related genes in plant-parasitic nematodes (G. pallida, Meloidogyne incognita, M. hapla and Bursaphelenchus xylophilus). This analysis suggested that it was not possible to identify G. pallida orthologues of the majority of C. elegans genes involved in the control of dauer formation. All these data suggest that G. pallida may use different mechanisms to C. elegans in regulating the survival stage.

Louisemarie Dandurand - One of the best experts on this subject based on the ideXlab platform.

  • characterization of the superoxide dismutase sod from the potato cyst nematode Globodera pallida
    Phytopathology, 2021
    Co-Authors: Nejra Solo, Joseph C Kuhl, Fangming Xiao, Allan Caplan, Joanna Kud, Louisemarie Dandurand
    Abstract:

    Potato cyst nematodes (PCN), such as Globodera pallida and Globodera rostochiensis, are some of the most agriculturally and economically important pests of potato. Upon nematode infection, a principle component of plant defense is the generation of the reactive oxygen species (ROS). Reactive oxygen species are highly toxic molecules that cause damage to pathogens and host alike. In order to successfully infect the plant, nematodes protect themselves from ROS through the activation of their own antioxidant processes and ROS scavenging enzymes. One of these enzymes is a superoxide dismutase (SOD; EC 1.15.1.1), which prevents cellular damage by catalyzing conversion of the superoxide radical (O2-˙) to hydrogen peroxide (H2O2) and molecular oxygen (O2). We have isolated a putatively secreted isoform of a Cu-Zn superoxide dismutase (SOD-3) from G. pallida and localized the expression of this gene in the posterior region of the nematode. Furthermore, we studied the expression of the SOD-3 gene during early parasitic stages of infection (24-72h) in the susceptible potato cv. Desiree, resistant potato cv. Innovator, and an immune host, Solanum sisymbriifolium. SOD-3 gene was significantly upregulated, regardless of the host type, however, the expression pattern differed between the susceptible and the resistant or immune hosts. This suggests that SOD-3 gene is responding to infection in plant roots differently depending upon whether the nematode is experiencing a compatible or an incompatible interaction.

  • genomic analyses of Globodera pallida a quarantine agricultural pathogen in idaho
    Pathogenetics, 2021
    Co-Authors: Sulochana K Wasala, Louisemarie Dandurand, Inga A Zasada, Dana K Howe, Dee R Denver
    Abstract:

    Globodera pallida is among the most significant plant-parasitic nematodes worldwide, causing major damage to potato production. Since it was discovered in Idaho in 2006, eradication efforts have aimed to contain and eradicate G. pallida through phytosanitary action and soil fumigation. In this study, we investigated genome-wide patterns of G. pallida genetic variation across Idaho fields to evaluate whether the infestation resulted from a single or multiple introduction(s) and to investigate potential evolutionary responses since the time of infestation. A total of 53 G. pallida samples (~1,042,000 individuals) were collected and analyzed, representing five different fields in Idaho, a greenhouse population, and a field in Scotland that was used for external comparison. According to genome-wide allele frequency and fixation index (Fst) analyses, most of the genetic variation was shared among the G. pallida populations in Idaho fields pre-fumigation, indicating that the infestation likely resulted from a single introduction. Temporal patterns of genome-wide polymorphisms involving (1) pre-fumigation field samples collected in 2007 and 2014 and (2) pre- and post-fumigation samples revealed nucleotide variants (SNPs, single-nucleotide polymorphisms) with significantly differentiated allele frequencies indicating genetic differentiation. This study provides insights into the genetic origins and adaptive potential of G. pallida invading new environments.

  • the Globodera pallida effector gppdi1 is a functional thioredoxin and triggers defense related cell death independent of its enzymatic activity
    Phytopathology, 2020
    Co-Authors: Rachel Gross, Louisemarie Dandurand, Joseph C Kuhl, Allan Caplan, Shan Zhang, Lihui Wei, Xiaofang Wang, Fangming Xiao
    Abstract:

    The plant-parasitic nematode Globodera pallida is an obligate biotroph that only reproduces on select species in the Solanum family. The establishment of the feeding site, the syncytium, involves secretion of effectors into the plant cell to combat the plant defense response and facilitate transformation of root cells into the syncytium. Despite the important predicted roles of effectors in the plant-pathogen interactions, the functionality of G. pallida effectors is largely unknown. In this study, we identified and characterized a G. pallida effector protein disulfide isomerase (GpPDI1). GpPDI1 contains two thioredoxin domains that function together to reduce disulfide bonds, as manifested by the nullification of enzymatic activity when either domain is absent. The transcript of GpPDI1 is localized in the dorsal gland of the nematode during the J2 stage. In addition, GpPDI1 can trigger defense-related cell death in Nicotiana benthamiana and tomato (Solanum lycopersicum) leaf tissue and localizes in the plant host cell's cytoplasm and nucleus when transiently expressed in plant cells. Significantly, the ability of elicitation of cell death is not dependent on the enzymatic activity of GpPDI1 or correlated with the subcellular distribution of GpPDI1, suggesting that a nondisulfide reducing function or structural feature of GpPDI1 is responsible for the recognition by the host immune system to elicit cell death.

  • initial responses of the trap crop solanum sisymbriifolium to Globodera pallida invasions
    The Plant Genome, 2020
    Co-Authors: Alexander Q Wixom, Louisemarie Dandurand, Carol N Casavant, Joseph C Kuhl, Fangming Xiao, Timothy J Sonnen, Allan Caplan
    Abstract:

    Many researchers today are looking for mechanisms underlying plant defenses against nematodes by identifying differentially expressed genes in domesticated hosts. In order to provide a different perspective, we analyzed the root transcriptome of an undomesticated non-host species, Solanum sisymbriifolium Lamark (SSI) before and after Globodera pallida infection. Utilizing RNAseq analyses, we identified changes in the expression of 277 transcripts. Many of these genes were not annotated; however, the annotated set included peroxidases, reactive oxygen species-producing proteins, and regulators of cell death. Importantly, 60% of the nematode-responsive genes did not respond to physical damage to root tissues, or to exogenous treatments with either salicylic acid or methyl jasmonate. Based on this, we speculate that the majority of changes in SSI gene expression were promoted by either nematode effectors, pathogen-associated molecular patterns (PAMPs), or by exposure to untested endogenous signaling molecules such as ethylene, or by exposure to multiple stimuli. This study incorporates our findings into a model that accounts for part of this plant's unusual resistance to nematodes.

  • a spatiotemporal analysis and dispersal patterns of the potato cyst nematode Globodera pallida in idaho
    Phytopathology, 2020
    Co-Authors: J B Contina, Louisemarie Dandurand, Guy R Knudsen
    Abstract:

    The potato cyst nematode Globodera pallida is a globally regulated potato pest. It was detected for the first time in the United States in the state of Idaho in 2006, and as of February 2019, the infestation is limited to 1,326 hectares. G. pallida is a specialized obligate sedentary endoparasite that can survive in the soil for up to 30 years in the absence of its potato host. In highly infested fields, the nematode can reduce tuber yields up to 80% and is spread mainly through the movement of soil, tubers, or farm equipment. The objectives of this study were to describe the spatiotemporal pattern of G. pallida in infested fields and model its dispersal patterns in southeastern Idaho. We used geostatistical tools and simulation models for precise mapping and to describe the relationships between G. pallida incidence and the spatial configurations. We found that the nematode is spatially clustered and prevalent around edges of fields, and its dispersal pattern followed the direction of cultivation. We found that the absence of potato in an infested field significantly reduced the number of cysts sampled each year subsequent to the initial delimitation sampling in 2007. Phytosanitary measures prohibiting the growth of potato contributed to stopping nematode reproduction, and the use of chemical fumigants and biofumigant cover crops contributed to a significant reduction in egg viability. We observed a process of a nonlinear decline in the prevalence of cysts as the distance separation from the primary infestation focus increased. A power law model was used to fit G. pallida dispersal capabilities. This study contributed to describing G. pallida infestation for Idaho. The goal of this study is to provide information on the spatial pattern and landscape ecology of G. pallida in Idaho for policy makers, industry, and researchers as well as facilitate common understandings on the challenges and opportunities for controlling this pest in Idaho.

Eric Grenier - One of the best experts on this subject based on the ideXlab platform.

  • monitoring and tackling genetic selection in the potato cyst nematode Globodera pallida
    EFSA Supporting Publications, 2020
    Co-Authors: Eric Grenier, Josselin Montarry, Sylvain Fournet, Sebastian Kiewnick, Geert Smant, Martijn Holterman, Johannes Helder, A Goverse
    Abstract:

    Management of plant pests is probably the most serious challenge in sustainable food production and the maintenance of food security. Due to the strict regulation of or ban on major categories of pesticide, the potato cyst nematode Globodera pallida has been managed by a combination of crop rotation and the potato resistance locus Grp1 , a relatively narrow range resistance gene which was introgressed into a range of commercial potato cultivars in Europe. However, in 2014, G. pallida populations were described that can no longer be controlled by Grp1 . Most likely similar highly virulent populations will also emerge in all major potato growing areas in North Western Europe where production practices are very similar. Except for laborious, costly and often moderately accurate pot experiments, there is currently no rapid and reliable method to identify virulent populations. This represents a strong limitation and prevents an accurate and durable management of infestations. The PalAdapt project funded by EFSA represents the first step of a European battle plan against the emergence of virulent G. pallida populations and aims at improving the methods and tools for a fast identification of virulence outbreaks. Four main research questions were investigated during the project: (i) Do resistance breaking populations correspond to novel introductions into Europe? (ii) Can miniaturized in vitro tests be used to get more rapidly an accurate identification of the virulence status?, (iii) Is cyst size a life history trait useful to estimate the virulence status of a population?, (iv) Can we identify polymorphism to design molecular tools for an accurate virulence monitoring? The EFSA partnering grants initiative was an accurate way to improve the EU risk assessment capacity through a knowledge exchange among partners having complementary resources and expertise.

  • plant parasite coevolution a weak signature of local adaptation between peruvian Globodera pallida populations and wild potatoes
    Ecology and Evolution, 2020
    Co-Authors: Camille Gautier, Eric Grenier, Sylvain Fournet, Lionel Renault, Christophe Piriou, Jeanclaude Yvin, Eric Nguemaona, Josselin Montarry
    Abstract:

    Plant-parasite coevolution has generated much interest and studies to understand and manage diseases in agriculture. Such a reciprocal evolutionary process could lead to a pattern of local adaptation between plants and parasites. Based on the phylogeography of each partner, the present study tested the hypothesis of local adaptation between the potato cyst nematode Globodera pallida and wild potatoes in Peru. The measured fitness trait was the hatching of cysts which is induced by host root exudates. Using a cross-hatching assay between 13 populations of G. pallida and root exudates from 12 wild potatoes, our results did not show a strong pattern of local adaptation of the parasite but the sympatric combinations induced better hatching of cysts than allopatric combinations, and there was a negative relationship between the hatching percentage and the geographical distance between nematode populations and wild potatoes. Moreover, a strong effect of the geographic origin of root exudates was found, with root exudates from south of Peru inducing better hatching than root exudates from north of Peru. These results could be useful to develop new biocontrol products or potato cultivars to limit damages caused by G. pallida.

  • the hidden diversity of the potato cyst nematode Globodera pallida in the south of peru
    Evolutionary Applications, 2020
    Co-Authors: Josselin Montarry, Magali Esquibet, Didier Fouville, Romain Thevenoux, Laurent Folcher, Eric Grenier
    Abstract:

    Our knowledge of the diversity of potato cyst nematodes in their native areas still remains patchy and should be improved. A previous study based on 42 Peruvian Globodera pallida populations revealed a clear south to north phylogeographic pattern, with five well-supported clades and maximum diversity observed in the south of Peru. In order to investigate this phylogeographic pattern more closely, we genotyped a larger collection of Peruvian populations using both cathepsin L gene sequence data and a new set of 13 microsatellite loci. Using different genetic analyses (STRUCTURE, DAPC), we consistently obtained the same results that led to similar conclusions: the presence of a larger genetic diversity than previously known suggesting the presence of cryptic species in the south of Peru. These investigations also allowed us to clarify the geographic borders of the previously described G. pallida genetic clades and to update our knowledge of the genetic structure of this species in its native area, with the presence of additional clades. A distance-based redundancy analysis (dbRDA) was also carried to understand whether there was a correlation between the population genetic differentiation and environmental conditions. This analysis showed that genetic distances observed between G. pallida populations are explained firstly by geographic distances, but also by climatic and soil conditions. This work could lead to a revision of the taxonomy that may have strong implications for risk assessment and management, especially on a quarantine species.

  • exploring the causes of small effective population sizes in cyst nematodes using artificial Globodera pallida populations
    Proceedings of The Royal Society B: Biological Sciences, 2019
    Co-Authors: Josselin Montarry, Eric Grenier, Sylvain Fournet, Sylvie Bardouvalette, Romain Mabon, Pierreloup Jan, Eric J Petit
    Abstract:

    The effective size of a population is the size of an ideal population which would undergo genetic drift at the same rate as the real population. The balance between selection and genetic drift depends on the effective population size (Ne), rather than the real numbers of individuals in the population (N). The objectives of the present study were to estimate Ne in the potato cyst nematode Globodera pallida and to explore the causes of a low Ne/N ratio in cyst nematodes using artificial populations. Using a temporal analysis of 24 independent populations, the median Ne was 58 individuals (min Ne = 25 and max Ne = 228). Ne is commonly lower than N but in the case of cyst nematodes, the Ne/N ratio was extremely low. Using artificial populations showed that this low ratio did not result from migration, selection and overlapping generations, but could be explain by the fact that G. pallida populations deviate in structure from the assumptions of the ideal population by having unequal sex ratios, high levels of ...

  • Phenotypic and Genomic Modifications Associated with Globodera pallida Adaptation to Potato Resistances
    Potato Research, 2018
    Co-Authors: Sylvain Fournet, Eric Grenier, Delphine Eoche-bosy, Marie-claire Kerlan, Josselin Montarry
    Abstract:

    Studying phenotypic and genomic modifications associated with pathogen adaptation to resistance is a crucial step to better understand and anticipate resistance breakdown. This short review summarizes recent results obtained using experimentally evolved populations of the potato cyst nematode Globodera pallida. In a first step, the variability of resistance durability was explored in four different potato genotypes carrying the resistance quantitative trait loci (QTL) GpaV(vrn) originating from Solanum vernei but differing by their genetic background. The consequences of the adaptation to resistance in terms of local adaptation, cross-virulence and virulence cost were then investigated. Finally, a genome scan approach was performed in order to identify the genomic regions involved in this adaptation. Results showed that nematode populations were able to adapt to the QTL GpaV(vrn), and that the plant genetic background has a strong impact on resistance durability. A trade-off between the adaptations to different resistant potato genotypes was detected, and we also showed that adaptation to the resistance QTL GpaV(vrn) from S. vernei did not allow adaptation to the colinear locus from S. sparsipilum (GpaV(spl)). Unexpectedly, the adaptation to resistance led to an increase of virulent individual's fitness on a susceptible host. Moreover, the genome scan approach allowed the highlighting of candidate genomic regions involved in adaptation to host plant resistance. This review shows that experimental evolution is an interesting tool to anticipate the adaptation of pathogen populations and could be very useful for identifying durable strategies for resistance deployment.

John T Jones - One of the best experts on this subject based on the ideXlab platform.

  • the gpia7 effector from the potato cyst nematode Globodera pallida targets potato ebp1 and interferes with the plant cell cycle programme
    Journal of Experimental Botany, 2021
    Co-Authors: Mirela C Coke, Catherine J Lilley, John T Jones, Peter Thorpe, Sophie Mantelin, Kathryn M Wright, Daniel S Shaw, Adams Chande
    Abstract:

    The potato cyst nematode Globodera pallida acquires all of its nutrients from an elaborate feeding site that it establishes in a host plant root. Normal development of the root cells is re-programmed in a process coordinated by secreted nematode effector proteins. The biological function of the G. pallida GpIA7 effector was investigated in this study. GpIA7 is specifically expressed in the subventral pharyngeal glands of pre-parasitic stage nematodes. Ectopic expression of GpIA7 in potato plants affected plant growth and development, suggesting a potential role for this effector in feeding site establishment. Potato plants overexpressing GpIA7 were shorter, with reduced tuber weight and delayed flowering. We provide evidence that GpIA7 associates with the plant growth regulator StEBP1 (ErbB-3 epidermal growth factor receptor-binding protein 1). GpIA7 modulates the regulatory function of StEBP1, altering the expression level of downstream target genes, including ribonucleotide reductase 2, cyclin D3;1 and retinoblastoma related 1, which are downregulated in plants overexpressing GpIA7. We provide an insight into the molecular mechanism used by the nematode to manipulate the host cell cycle and provide evidence that this may rely, at least in part, on hindering the function of host EBP1.

  • Activation of hatching in diapaused and quiescent Globodera pallida
    2016
    Co-Authors: Juan E. Palomares-rius, John T Jones, Peter J. Cock, Pablo Castillo, Vivian C. Blok
    Abstract:

    The potato cyst nematodes (PCN) Globodera pallida and G. rostochiensis are major pests of potatoes. The G. pallida (and G. rostochiensis) life cycle includes both diapause and quiescent stages. Nematodes in dormancy (diapause or quiescent) are adapted for long-term survival and are more resistant to nematicides. This study analysed the mechanisms underlying diapause and quiescence. The effects of several compounds (8Br-cGMP, oxotremorine and atropine) on the activation of hatching were studied. The measurements of some morphometric parameters in diapaused and quiescent eggs after exposure to PRD revealed differences in dorsal gland length, subventral gland length and dorsal gland nucleolus. In addition, the expression of 2 effectors (IVg9 and cellulase) was not induced in diapaused eggs in water or PRD, while expression was slightly induced in quiescent eggs. Finally, we performed a comparative study to identify orthologues of C. elegans diapause related genes in plant-parasitic nematodes (G. pallida, Meloidogyne incognita, M. hapla and Bursaphelenchus xylophilus). This analysis suggested that it was not possible to identify G. pallida orthologues of the majority of C. elegans genes involved in the control of dauer formation. All these data suggest that G. pallida may use different mechanisms to C. elegans in regulating the survival stage. Key words: hatching, cGMP, muscarinic pathway, potato cyst nematodes, root diffusate

  • horizontal gene transfer from bacteria has enabled the plant parasitic nematode Globodera pallida to feed on host derived sucrose
    Molecular Biology and Evolution, 2016
    Co-Authors: Etienne G J Danchin, John T Jones, Sophie Mantelin, Elena A Guzeeva, A Berepiki
    Abstract:

    The evolution of plant-parasitic nematodes (PPN) is unusual in that these organisms have acquired a range of genes from bacteria via horizontal gene transfer (HGT). The proteins encoded by most of these genes are involved in metabolism of various components of the plant cell wall during invasion of the host. Recent genome sequencing projects for PPN have shown that Glycosyl Hydrolase Family 32 (GH32) sequences are present in several PPN species. These sequences are absent from almost all other animals. Here, we show that the GH32 sequences from an economically important cyst nematode species, Globodera pallida are functional invertases, are expressed during feeding and are restricted in expression to the nematode digestive system. These data are consistent with a role in metabolizing host-derived sucrose. In addition, a detailed phylogenetic analysis shows that the GH32 sequences from PPN and those present in some insect species have distinct bacterial origins and do not therefore derive from a gene present in the last common ancestor of ecdysozoan species. HGT has therefore played at least two critical roles in the evolution of PPN, enabling both invasion of the host and feeding on the main translocation carbohydrate of the plant.

  • gene expression changes in diapause or quiescent potato cyst nematode Globodera pallida eggs after hydration or exposure to tomato root diffusate
    PeerJ, 2016
    Co-Authors: Pete E. Hedley, Peter J. A. Cock, Jenny Morris, John T Jones, Juan E Palomaresrius, Vivian C. Blok
    Abstract:

    Plant-parasitic nematodes (PPN) need to be adapted to survive in the absence of a suitable host or in hostile environmental conditions. Various forms of developmental arrest including hatching inhibition and dauer stages are used by PPN in order to survive these conditions and spread to other areas. Potato cyst nematodes (PCN) (Globodera pallida and G. rostochiensis) are frequently in an anhydrobiotic state, with unhatched nematode persisting for extended periods of time inside the cyst in the absence of the host. This paper shows fundamental changes in the response of quiescent and diapaused eggs of G. pallida to hydration and following exposure to tomato root diffusate (RD) using microarray gene expression analysis encompassing a broad set of genes. For the quiescent eggs, 547 genes showed differential expression following hydration vs. hydratation and RD (H-RD) treatment whereas 708 genes showed differential regulation for the diapaused eggs following these treatments. The comparison between hydrated quiescent and diapaused eggs showed marked differences, with 2,380 genes that were differentially regulated compared with 987 genes following H-RD. Hydrated quiescent and diapaused eggs were markedly different indicating differences in adaptation for long-term survival. Transport activity is highly up-regulated following H-RD and few genes were coincident between both kinds of eggs. With the quiescent eggs, the majority of genes were related to ion transport (mainly sodium), while the diapaused eggs showed a major diversity of transporters (amino acid transport, ion transport, acetylcholine or other molecules).

  • activation of hatching in diapaused and quiescent Globodera pallida
    Parasitology, 2013
    Co-Authors: Juan E Palomaresrius, John T Jones, Peter J. A. Cock, Pablo Castillo, Vivian C. Blok
    Abstract:

    The potato cyst nematodes (PCN) Globodera pallida and G. rostochiensis are major pests of potatoes. The G. pallida (and G. rostochiensis) life cycle includes both diapause and quiescent stages. Nematodes in dormancy (diapause or quiescent) are adapted for long-term survival and are more resistant to nematicides. This study analysed the mechanisms underlying diapause and quiescence. The effects of several compounds (8Br-cGMP, oxotremorine and atropine) on the activation of hatching were studied. The measurements of some morphometric parameters in diapaused and quiescent eggs after exposure to PRD revealed differences in dorsal gland length, subventral gland length and dorsal gland nucleolus. In addition, the expression of 2 effectors (IVg9 and cellulase) was not induced in diapaused eggs in water or PRD, while expression was slightly induced in quiescent eggs. Finally, we performed a comparative study to identify orthologues of C. elegans diapause related genes in plant-parasitic nematodes (G. pallida, Meloidogyne incognita, M. hapla and Bursaphelenchus xylophilus). This analysis suggested that it was not possible to identify G. pallida orthologues of the majority of C. elegans genes involved in the control of dauer formation. All these data suggest that G. pallida may use different mechanisms to C. elegans in regulating the survival stage.

Didier Mugniery - One of the best experts on this subject based on the ideXlab platform.

  • Origin and genetic diversity of Western European populations of the potato cyst nematode (Globodera pallida) inferred from mitochondrial sequences and microsatellite loci
    Molecular Ecology, 2008
    Co-Authors: Olivier Plantard, Eric Grenier, D Picard, M Scurrah, Sylvie Valette, Didier Mugniery
    Abstract:

    Native to South America, the potato cyst nematode Globodera pallida is one of the principal pests of Andean potato crops and is also an important global pest following its introduction to Europe, Africa, North America, Asia and Oceania. Building on earlier work showing a clear south to north phylogeographic pattern in Peruvian populations, we have been able to identify the origin of Western European populations with high accuracy. They are all derived from a single restricted area in the extreme south of Peru, located between the north shore of the Lake Titicaca and Cusco. Only four cytochrome b haplotypes are found in Western Europe, one of them being also found in some populations of this area of southern Peru. The allelic richness at seven microsatellite loci observed in the Western European populations, although only one-third of that observed in this part of southern Peru, is comparable to the allelic richness observed in the northern region of Peru. This result could be explained by the fact that most of the genetic variability observed at the scale of a field or even of a region is already observed at the scale of a single plant within a field. Thus, even introduction via a single infected potato plant could result in the relatively high genetic variability observed in Western Europe. This finding has important consequences for the control of this pest and the development of quarantine measures.

  • resistance quantitative trait loci originating from solanum sparsipilum act independently on the sex ratio of Globodera pallida and together for developing a necrotic reaction
    Molecular Plant-microbe Interactions, 2005
    Co-Authors: Bernard Caromel, Marie-claire Kerlan, Didier Mugniery, Sandra Andrzejewski, Daniel Ellisseche, Francoise Roussellebourgeois, Alain Palloix, V Lefebvre
    Abstract:

    Plant resistance to nematodes is related to the ability of the host to reduce the development of nematode juveniles into females. Resistance to the potato cyst nematode (PCN) Globodera pallida, originating from the wild species Solanum sparsipilum, was dissected by a quantitative trait loci (QTL) approach. Two QTL explained 89% of the phenotypic variation. The QTL GpaVsspl on chromosome V displayedthe major effect on the cyst number (coefficient of determination [R2] = 76.6%). It restricted G. pallida development to 16.2% of juveniles, 81.5% of males, and 2.3% of females. The QTL GpaXIsspl chromosome XI displayed a lower effect on the cyst number (R2 = 12.7%). It restricted G. pallida development to 13.8% of juveniles, 35.4% of males, and 50.8% of females. Clones carrying both QTL restricted the nematode development to 58.1% juveniles, 41.1% of males, and 0.8% of females. We demonstrated that potato clones carrying both QTL showed a strong necrotic reaction in roots infected by nematodes, while no such re...

  • resistance quantitative trait loci originating from solanum sparsipilum act independently on the sex ratio of Globodera pallida and together for developing a necrotic reaction
    Molecular Plant-microbe Interactions, 2005
    Co-Authors: Bernard Caromel, Marie-claire Kerlan, Didier Mugniery, Sandra Andrzejewski, Daniel Ellisseche, Francoise Roussellebourgeois, Alain Palloix, Veronique Lefebvre
    Abstract:

    Plant resistance to nematodes is related to the ability of the host to reduce the development of nematode juveniles into females. Resistance to the potato cyst nematode (PCN) Globodera pallida, originating from the wild species Solanum sparsipilum, was dissected by a quantitative trait loci (QTL) approach. Two QTL explained 89% of the phenotypic variation. The QTL GpaV(s)spl on chromosome V displayed the major effect on the cyst number (coefficient of determination [R2] = 76.6%). It restricted G. pallida development to 16.2% of juveniles, 81.5% of males, and 2.3% of females. The QTL GpaXI(s)spl on chromosome XI displayed a lower effect on the cyst number (R2 = 12.7%). It restricted G. pallida development to 13.8% of juveniles, 35.4% of males, and 50.8% of females. Clones carrying both QTL restricted the nematode development to 58.1% juveniles, 41.1% of males, and 0.8% of females. We demonstrated that potato clones carrying both QTL showed a strong necrotic reaction in roots infected by nematodes, while no such reaction was observed in clones carrying a single QTL. This result underlines the importance to introgress together GpaV(s)spl and GpaXI(s)spl into potato cultivars, in order to reduce the density of this quarantine pest in soil and to decrease the risk of selecting overcoming G. pallida subpopulations.

  • inbreeding and population structure of the potato cyst nematode Globodera pallida in its native area peru
    Molecular Ecology, 2004
    Co-Authors: D Picard, Olivier Plantard, M Scurrah, Didier Mugniery
    Abstract:

    The dispersal abilities and the population genetic structure of nematodes living in the soil are poorly known. In the present study, we have pursued these issues in the potato cyst nematode Globodera pallida, which parasitizes potato roots and is indigenous to South America. A hierarchical sampling regime was conducted in Peru to investigate gene flow on regional, field and plant scales. Multilocus genotypes of single individuals were obtained using eight polymorphic microsatellites markers. Large heterozygote deficiencies were observed at most loci. The limited active dispersal of larvae from their cyst, which favours mating between (half) siblings, could be responsible for this pattern. Within fields, as well as among fields within regions (even 35 km apart), low FST values suggest extensive gene flow. Among fields within regions, only 1.5–4.4% genetic variability was observed. Passive dispersal of cysts by natural means (wind, running water, or wild animals) or by anthropogenic means (tillage, movement of infected seed tubers) is probably responsible for the results observed. Among regions, high FST values were observed. Thus long-range dispersal (more than 320 km apart) is probably limited by major biogeographical barriers such as the mountains found in the Andean Cordillera. These results provide useful information for the management of resistant varieties, to slow down the emergence and spread of resistance-breaking pathotypes.

  • mapping qtls for resistance against Globodera pallida stone pa2 3 in a diploid potato progeny originating from solanum spegazzinii
    Theoretical and Applied Genetics, 2003
    Co-Authors: Bernard Caromel, Didier Mugniery, Veronique Lefebvre, Sandra Andrzejewski, Daniel Ellisseche, Mc Kerlan, P Rousselle, Francoise Roussellebourgeois
    Abstract:

    A "F1" diploid population between Solanum tuberosum 2x and the wild Solanum spegazzinii was studied. It segregated for resistance against the potato cyst nematode Globodera pallida derived from the wild species. The inheritance had a quantitative nature. Linkage maps of AFLP and RFLP markers were constructed for both parents. Three QTLs were identified on the map of the resistant parent on chromosomes V, VI and XII, respectively. The first one had a major effect and explained more than 50% of the total variance of resistance. It is located in a cluster of resistance genes and may be the same locus as Gpa which has been described formerly. The two others explained about 20% of the total variance each. The QTL on chromosome XII is also in a cluster of resistance genes, and in an orthologous position with resistance genes against nematodes in tomato and pepper.