Publications by authors named "Catherine J Lilley"

33 Publications

Toward genetic modification of plant-parasitic nematodes: delivery of macromolecules to adults and expression of exogenous mRNA in second stage juveniles.

G3 (Bethesda) 2021 Feb;11(2)

Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK.

Plant-parasitic nematodes are a continuing threat to food security, causing an estimated 100 billion USD in crop losses each year. The most problematic are the obligate sedentary endoparasites (primarily root knot nematodes and cyst nematodes). Progress in understanding their biology is held back by a lack of tools for functional genetics: forward genetics is largely restricted to studies of natural variation in populations and reverse genetics is entirely reliant on RNA interference. There is an expectation that the development of functional genetic tools would accelerate the progress of research on plant-parasitic nematodes, and hence the development of novel control solutions. Here, we develop some of the foundational biology required to deliver a functional genetic tool kit in plant-parasitic nematodes. We characterize the gonads of male Heterodera schachtii and Meloidogyne hapla in the context of spermatogenesis. We test and optimize various methods for the delivery, expression, and/or detection of exogenous nucleic acids in plant-parasitic nematodes. We demonstrate that delivery of macromolecules to cyst and root knot nematode male germlines is difficult, but possible. Similarly, we demonstrate the delivery of oligonucleotides to root knot nematode gametes. Finally, we develop a transient expression system in plant-parasitic nematodes by demonstrating the delivery and expression of exogenous mRNA encoding various reporter genes throughout the body of H. schachtii juveniles using lipofectamine-based transfection. We anticipate these developments to be independently useful, will expedite the development of genetic modification tools for plant-parasitic nematodes, and ultimately catalyze research on a group of nematodes that threaten global food security.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/g3journal/jkaa058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8022973PMC
February 2021

Identification and characterisation of serotonin signalling in the potato cyst nematode Globodera pallida reveals new targets for crop protection.

PLoS Pathog 2020 10 2;16(10):e1008884. Epub 2020 Oct 2.

School of Biological Sciences, University of Southampton, Southampton, United Kingdom.

Plant parasitic nematodes are microscopic pathogens that invade plant roots and cause extensive damage to crops. We have used a chemical biology approach to define mechanisms underpinning their parasitic behaviour: We discovered that reserpine, a plant alkaloid that inhibits the vesicular monoamine transporter (VMAT), potently impairs the ability of the potato cyst nematode Globodera pallida to enter the host plant root. We show this is due to an inhibition of serotonergic signalling that is essential for activation of the stylet which is used to access the host root. Prompted by this we identified core molecular components of G. pallida serotonin signalling encompassing the target of reserpine, VMAT; the synthetic enzyme for serotonin, tryptophan hydroxylase; the G protein coupled receptor SER-7 and the serotonin-gated chloride channel MOD-1. We cloned each of these molecular components and confirmed their functional identity by complementation of the corresponding C. elegans mutant thus mapping out serotonergic signalling in G. pallida. Complementary approaches testing the effect of chemical inhibitors of each of these signalling elements on discrete sub-behaviours required for parasitism and root invasion reinforce the critical role of serotonin. Thus, targeting the serotonin signalling pathway presents a promising new route to control plant parasitic nematodes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.ppat.1008884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556481PMC
October 2020

Plant-parasitic nematodes respond to root exudate signals with host-specific gene expression patterns.

PLoS Pathog 2019 02 1;15(2):e1007503. Epub 2019 Feb 1.

Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.

Plant parasitic nematodes must be able to locate and feed from their host in order to survive. Here we show that Pratylenchus coffeae regulates the expression of selected cell-wall degrading enzyme genes relative to the abundance of substrate in root exudates, thereby tailoring gene expression for root entry of the immediate host. The concentration of cellulose or xylan within the exudate determined the level of β-1,4-endoglucanase (Pc-eng-1) and β-1,4-endoxylanase (Pc-xyl) upregulation respectively. Treatment of P. coffeae with cellulose or xylan or with root exudates deficient in cellulose or xylan conferred a specific gene expression response of Pc-eng-1 or Pc-xyl respectively with no effect on expression of another cell wall degrading enzyme gene, a pectate lyase (Pc-pel). RNA interference confirmed the importance of regulating these genes as lowered transcript levels reduced root penetration by the nematode. Gene expression in this plant parasitic nematode is therefore influenced, in a host-specific manner, by cell wall components that are either secreted by the plant or released by degradation of root tissue. Transcriptional plasticity may have evolved as an adaptation for host recognition and increased root invasion by this polyphagous species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.ppat.1007503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373980PMC
February 2019

Host-specific signatures of the cell wall changes induced by the plant parasitic nematode, Meloidogyne incognita.

Sci Rep 2018 11 23;8(1):17302. Epub 2018 Nov 23.

Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, Leeds, United Kingdom.

Root-knot nematodes (Meloidogyne spp.) are an important group of plant parasitic nematodes that induce within host plant roots unique feeding site structures, termed giant cells, which supply nutrient flow to the nematode. A comparative in situ analysis of cell wall polysaccharides in the giant cells of three host species (Arabidopsis, maize and aduki bean) infected with Meloidogyne incognita has been carried out. Features common to giant cell walls of all three species include the presence of high-esterified pectic homogalacturonan, xyloglucan and pectic arabinan. The species-specific presence of xylan and mixed-linkage glucan (MLG) epitopes in giant cell walls of maize reflected that host's taxonomic group. The LM5 galactan and LM21 mannan epitopes were not detected in the giant cell walls of aduki bean but were detected in Arabidopsis and maize giant cell walls. The LM2 arabinogalactan-protein epitope was notable for its apparent global variations in root cell walls as a response to infection across the three host species. Additionally, a set of Arabidopsis cell wall mutants were used to determine any impacts of altered cell wall structures on M. incognita infection. Disruption of the arabinogalactan-protein 8 gene had the greatest impact and resulted in an increased infection rate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-35529-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251906PMC
November 2018

Aphid Colonization Affects Potato Root Exudate Composition and the Hatching of a Soil Borne Pathogen.

Front Plant Sci 2018 6;9:1278. Epub 2018 Sep 6.

Centre for Plant Sciences, University of Leeds, Leeds, United Kingdom.

Plants suffer multiple, simultaneous biotic threats from both above and below ground. These pests and/or pathogens are commonly studied on an individual basis and the effects of above-ground pests on below-ground pathogens are poorly defined. Root exudates from potato plants ( L.) were analyzed to characterize the top-down plant-mediated interactions between a phloem-sucking herbivore () and a sedentary, endoparasitic nematode (). Increasing inocula of the aphid, , reduced the root mass of potato plants. Exudates collected from these roots induced significantly lower hatching of second-stage juveniles from eggs over a 28-day period, than those from uninfested control plants. Inhibition of hatch was significantly positively correlated with size of aphid inoculum. Diminished hatching was partially recovered after treatment with root exudate from uninfested potato plants indicating that the effect on hatching is reversible but cannot be fully recovered. Glucose and fructose content was reduced in root exudates from aphid-infested potato plants compared to controls and these sugars were found to induce hatching of , but not to the same degree as potato root exudates (PRE). Supplementing aphid-infested PRE with sugars did not recover the hatching potential of the treatment, suggesting that additional compounds play an important role in egg hatch. The first gene upregulated in the closely related potato cyst nematode post-exposure to host root exudate, , was confirmed to be upregulated in cysts after exposure to PRE and was also upregulated by the sugar treatments. Significantly reduced upregulation of was observed in cysts treated with root exudates from potato plants infested with greater numbers of aphids. Our data suggest that aphid infestation of potato plants affects the composition of root exudates, with consequential effects on the hatching and gene expression of eggs. This work shows that an above-ground pest can indirectly impact the rhizosphere and reveals secondary effects for control of an economically important below-ground pathogen.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2018.01278DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136236PMC
September 2018

Effector gene birth in plant parasitic nematodes: Neofunctionalization of a housekeeping glutathione synthetase gene.

PLoS Genet 2018 04 11;14(4):e1007310. Epub 2018 Apr 11.

Dept. of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, United Kingdom.

Plant pathogens and parasites are a major threat to global food security. Plant parasitism has arisen four times independently within the phylum Nematoda, resulting in at least one parasite of every major food crop in the world. Some species within the most economically important order (Tylenchida) secrete proteins termed effectors into their host during infection to re-programme host development and immunity. The precise detail of how nematodes evolve new effectors is not clear. Here we reconstruct the evolutionary history of a novel effector gene family. We show that during the evolution of plant parasitism in the Tylenchida, the housekeeping glutathione synthetase (GS) gene was extensively replicated. New GS paralogues acquired multiple dorsal gland promoter elements, altered spatial expression to the secretory dorsal gland, altered temporal expression to primarily parasitic stages, and gained a signal peptide for secretion. The gene products are delivered into the host plant cell during infection, giving rise to "GS-like effectors". Remarkably, by solving the structure of GS-like effectors we show that during this process they have also diversified in biochemical activity, and likely represent the founding members of a novel class of GS-like enzyme. Our results demonstrate the re-purposing of an endogenous housekeeping gene to form a family of effectors with modified functions. We anticipate that our discovery will be a blueprint to understand the evolution of other plant-parasitic nematode effectors, and the foundation to uncover a novel enzymatic function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1007310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5919673PMC
April 2018

A High-Throughput Molecular Pipeline Reveals the Diversity in Prevalence and Abundance of Pratylenchus and Meloidogyne Species in Coffee Plantations.

Phytopathology 2018 May 11;108(5):641-650. Epub 2018 Apr 11.

First, second, sixth, and eighth authors: Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom; third author: Embrapa Café/Inovacafé, Lavras, Brazil; fourth author: WASI, Buon Ma Thuot, Vietnam; fifth author: UNILA, Bandar Lampung, Indonesia; and seventh author: Nestle R.D. Tours, France.

Coffee yields are adversely affected by plant-parasitic nematodes and the pathogens are largely underreported because a simple and reliable identification method is not available. We describe a polymerase chain reaction-based approach to rapidly detect and quantify the major Pratylenchus and Meloidogyne nematode species that are capable of parasitizing coffee. The procedure was applied to soil samples obtained from a number of coffee farms in Brazil, Vietnam, and Indonesia to assess the prevalence of these species associated both with coffee (Coffea arabica and C. canephora) and its intercropped species Musa acuminata (banana) and Piper nigrum (black pepper). Pratylenchus coffeae and P. brachyurus were associated with coffee in all three countries but there were distinct profiles of Meloidogyne spp. Meloidogyne incognita, M. exigua, and M. paranaensis were identified in samples from Brazil and M. incognita and M. hapla were detected around the roots of coffee in Vietnam. No Meloidogyne spp. were detected in samples from Indonesia. There was a high abundance of Meloidogyne spp. in soil samples in which Pratylenchus spp. were low or not detected, suggesting that the success of one genus may deter another. Meloidogyne spp. in Vietnam and Pratylenchus spp. in Indonesia were more numerous around intercropped plants than in association with coffee. The data suggest a widespread but differential nematode problem associated with coffee production across the regions studied. The issue is compounded by the current choice of intercrops that support large nematode populations. Wider application of the approach would elucidate the true global scale of the nematode problem and the cost to coffee production. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1094/PHYTO-10-17-0343-RDOI Listing
May 2018

A Plant-Feeding Nematode Indirectly Increases the Fitness of an Aphid.

Front Plant Sci 2017 3;8:1897. Epub 2017 Nov 3.

Centre for Plant Sciences, University of Leeds, Leeds, United Kingdom.

Plants suffer multiple, simultaneous assaults from above and below ground. In the laboratory, pests and/or pathogen attack are commonly studied on an individual basis. The molecular response of the plant to attack from multiple organisms and the interaction of different defense pathways is unclear. The inducible systemic responses of the potato ( L.) host plant were analyzed to characterize the plant-mediated indirect interactions between a sedentary, endoparasitic nematode (), and a phloem-sucking herbivore (). The reproductive success of was greater on potato plants pre-infected with compared to control plants. Salicylic acid (SA) increased systemically in the leaves of potato plants following nematode and aphid infection singly with a corresponding increase in expression of SA-mediated marker genes. An increase in jasmonic acid associated with aphid infection was suppressed when plants were co-infected with nematodes. Our data suggests a positive, asymmetric interaction between a sedentary endoparasitic nematode and a sap-sucking insect. The systemic response of the potato plant following infection with indirectly influences the performance of . This work reveals additional secondary benefits of controlling individual crop pests.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2017.01897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701616PMC
November 2017

The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant.

Front Plant Sci 2017 21;8:1087. Epub 2017 Jun 21.

Faculty of Biological Sciences, University of LeedsLeeds, United Kingdom.

Plant-parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, , , and , in their respective potato, soybean, and spring wheat host roots. fluorescence analysis revealed highly similar cell wall composition of syncytia induced by and . Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by and contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2017.01087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5478703PMC
June 2017

Expression of a Cystatin Transgene in Eggplant Provides Resistance to Root-knot Nematode, Meloidogyne incognita.

Front Plant Sci 2016 28;7:1122. Epub 2016 Jul 28.

Division of Nematology, ICAR-Indian Agricultural Research Institute New Delhi, India.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2016.01122DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4963396PMC
August 2016

The genome of the yellow potato cyst nematode, Globodera rostochiensis, reveals insights into the basis of parasitism and virulence.

Genome Biol 2016 Jun 10;17(1):124. Epub 2016 Jun 10.

USDA-ARS Horticultural Crops Research Laboratory, Corvallis, OR, USA.

Background: The yellow potato cyst nematode, Globodera rostochiensis, is a devastating plant pathogen of global economic importance. This biotrophic parasite secretes effectors from pharyngeal glands, some of which were acquired by horizontal gene transfer, to manipulate host processes and promote parasitism. G. rostochiensis is classified into pathotypes with different plant resistance-breaking phenotypes.

Results: We generate a high quality genome assembly for G. rostochiensis pathotype Ro1, identify putative effectors and horizontal gene transfer events, map gene expression through the life cycle focusing on key parasitic transitions and sequence the genomes of eight populations including four additional pathotypes to identify variation. Horizontal gene transfer contributes 3.5 % of the predicted genes, of which approximately 8.5 % are deployed as effectors. Over one-third of all effector genes are clustered in 21 putative 'effector islands' in the genome. We identify a dorsal gland promoter element motif (termed DOG Box) present upstream in representatives from 26 out of 28 dorsal gland effector families, and predict a putative effector superset associated with this motif. We validate gland cell expression in two novel genes by in situ hybridisation and catalogue dorsal gland promoter element-containing effectors from available cyst nematode genomes. Comparison of effector diversity between pathotypes highlights correlation with plant resistance-breaking.

Conclusions: These G. rostochiensis genome resources will facilitate major advances in understanding nematode plant-parasitism. Dorsal gland promoter element-containing effectors are at the front line of the evolutionary arms race between plant and parasite and the ability to predict gland cell expression a priori promises rapid advances in understanding their roles and mechanisms of action.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13059-016-0985-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4901422PMC
June 2016

Functional C-TERMINALLY ENCODED PEPTIDE (CEP) plant hormone domains evolved de novo in the plant parasite Rotylenchulus reniformis.

Mol Plant Pathol 2016 Oct 6;17(8):1265-75. Epub 2016 Jun 6.

Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.

Sedentary plant-parasitic nematodes (PPNs) induce and maintain an intimate relationship with their host, stimulating cells adjacent to root vascular tissue to re-differentiate into unique and metabolically active 'feeding sites'. The interaction between PPNs and their host is mediated by nematode effectors. We describe the discovery of a large and diverse family of effector genes, encoding C-TERMINALLY ENCODED PEPTIDE (CEP) plant hormone mimics (RrCEPs), in the syncytia-forming plant parasite Rotylenchulus reniformis. The particular attributes of RrCEPs distinguish them from all other CEPs, regardless of origin. Together with the distant phylogenetic relationship of R. reniformis to the only other CEP-encoding nematode genus identified to date (Meloidogyne), this suggests that CEPs probably evolved de novo in R. reniformis. We have characterized the first member of this large gene family (RrCEP1), demonstrating its significant up-regulation during the plant-nematode interaction and expression in the effector-producing pharyngeal gland cell. All internal CEP domains of multi-domain RrCEPs are followed by di-basic residues, suggesting a mechanism for cleavage. A synthetic peptide corresponding to RrCEP1 domain 1 is biologically active and capable of up-regulating plant nitrate transporter (AtNRT2.1) expression, whilst simultaneously reducing primary root elongation. When a non-CEP-containing, syncytia-forming PPN species (Heterodera schachtii) infects Arabidopsis in a CEP-rich environment, a smaller feeding site is produced. We hypothesize that CEPs of R. reniformis represent a two-fold adaptation to sustained biotrophy in this species: (i) increasing host nitrate uptake, whilst (ii) limiting the size of the syncytial feeding site produced.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/mpp.12402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103176PMC
October 2016

A metagenetic approach to determine the diversity and distribution of cyst nematodes at the level of the country, the field and the individual.

Mol Ecol 2015 Dec;24(23):5842-51

Cell and Molecular Sciences Group, Dundee Effector Consortium, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.

Distinct populations of the potato cyst nematode (PCN) Globodera pallida exist in the UK that differ in their ability to overcome various sources of resistance. An efficient method for distinguishing between populations would enable pathogen-informed cultivar choice in the field. Science and Advice for Scottish Agriculture (SASA) annually undertake national DNA diagnostic tests to determine the presence of PCN in potato seed and ware land by extracting DNA from soil floats. These DNA samples provide a unique resource for monitoring the distribution of PCN and further interrogation of the diversity within species. We identify a region of mitochondrial DNA descriptive of three main groups of G. pallida present in the UK and adopt a metagenetic approach to the sequencing and analysis of all SASA samples simultaneously. Using this approach, we describe the distribution of G. pallida mitotypes across Scotland with field-scale resolution. Most fields contain a single mitotype, one-fifth contain a mix of mitotypes, and less than 3% contain all three mitotypes. Within mixed fields, we were able to quantify the relative abundance of each mitotype across an order of magnitude. Local areas within mixed fields are dominated by certain mitotypes and indicate towards a complex underlying 'pathoscape'. Finally, we assess mitotype distribution at the level of the individual cyst and provide evidence of 'hybrids'. This study provides a method for accurate, quantitative and high-throughput typing of up to one thousand fields simultaneously, while revealing novel insights into the national genetic variability of an economically important plant parasite.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/mec.13434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981918PMC
December 2015

Expression of a cystatin transgene can confer resistance to root lesion nematodes in Lilium longiflorum cv. 'Nellie White'.

Transgenic Res 2015 Jun 15;24(3):421-32. Epub 2014 Nov 15.

Floral and Nursery Plants Research Unit, U.S. National Arboretum, U.S. Department of Agriculture (USDA) ARS, BARC West, 10300 Baltimore Avenue, Building 010A Room 126, Beltsville, MD, 20705-2350, USA,

Lilium longiflorum cv. 'Nellie White' assumes a great economic importance as cut flowers, being one of the most valuable species (annual pot plants value above $20,000,000) in terms of wholesales in the US. The root lesion nematode Pratylenchus penetrans (RLN) constitutes one of the main pests for lily producers due to the significant root damage it causes. Our efforts have focused on the generation of soybean hairy roots (as a transient test model) and stable transgenic lilies overexpressing a modified rice cystatin (Oc-IΔD86) transgene and challenged with root lesion nematodes. Lily transformation was achieved by gene gun co-bombardment using both a pBluescript-based vector containing the cystatin gene and pDM307 that contains a bar gene for phosphinothricin selection. Both soybean hairy roots and lilies overexpressing the OcIΔD86 transgene exhibited enhanced resistance to RLN infection by means of nematode reduction up to 75 ± 5% on the total number of nematodes. In addition, lily plants overexpressing OcIΔD86 displayed an increase of plant mass and better growth performance in comparison to wild-type plants, thereby demonstrating an alternative strategy for increasing the yield and reducing nematode damage to this important floral crop.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11248-014-9848-2DOI Listing
June 2015

Genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida.

BMC Genomics 2014 Oct 23;15:923. Epub 2014 Oct 23.

The James Hutton Institute, Dundee Effector Consortium, Invergowrie, Dundee DD2 5DA, UK.

Background: 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.

Results: 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.

Conclusion: 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1471-2164-15-923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4213498PMC
October 2014

Identification and characterisation of a hyper-variable apoplastic effector gene family of the potato cyst nematodes.

PLoS Pathog 2014 Sep 25;10(9):e1004391. Epub 2014 Sep 25.

Centre for Plant Sciences, University of Leeds, Leeds, United Kingdom.

Sedentary endoparasitic nematodes are obligate biotrophs that modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Using assumptions about the characteristics of genes involved in plant-nematode biotrophic interactions to inform the identification strategy, we provide a description and characterisation of a novel group of hyper-variable extracellular effectors termed HYP, from the potato cyst nematode Globodera pallida. HYP effectors comprise a large gene family, with a modular structure, and have unparalleled diversity between individuals of the same population: no two nematodes tested had the same genetic complement of HYP effectors. Individuals vary in the number, size, and type of effector subfamilies. HYP effectors are expressed throughout the biotrophic stages in large secretory cells associated with the amphids of parasitic stage nematodes as confirmed by in situ hybridisation. The encoded proteins are secreted into the host roots where they are detectable by immunochemistry in the apoplasm, between the anterior end of the nematode and the feeding site. We have identified HYP effectors in three genera of plant parasitic nematodes capable of infecting a broad range of mono- and dicotyledon crop species. In planta RNAi targeted to all members of the effector family causes a reduction in successful parasitism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.ppat.1004391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177990PMC
September 2014

The transcriptome of Nacobbus aberrans reveals insights into the evolution of sedentary endoparasitism in plant-parasitic nematodes.

Genome Biol Evol 2014 Aug 13;6(9):2181-94. Epub 2014 Aug 13.

Cell and Molecular Sciences Group, Dundee Effector Consortium, James Hutton Institute, Dundee, United Kingdom

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/gbe/evu171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4202313PMC
August 2014

The genome and life-stage specific transcriptomes of Globodera pallida elucidate key aspects of plant parasitism by a cyst nematode.

Genome Biol 2014 Mar 3;15(3):R43. Epub 2014 Mar 3.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/gb-2014-15-3-r43DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054857PMC
March 2014

The feeding tube of cyst nematodes: characterisation of protein exclusion.

PLoS One 2014 28;9(1):e87289. Epub 2014 Jan 28.

Centre for Plant Sciences, University of Leeds, Leeds, United Kingdom.

Plant parasitic nematodes comprise several groups; the most economically damaging of these are the sedentary endoparasites. Sedentary endoparasitic nematodes are obligate biotrophs and modify host root tissue, using a suite of effector proteins, to create a feeding site that is their sole source of nutrition. They feed by withdrawing host cell assimilate from the feeding site though a structure known as the feeding tube. The function, composition and molecular characteristics of feeding tubes are poorly characterised. It is hypothesised that the feeding tube facilitates uptake of host cell assimilate by acting as a molecular sieve. Several studies, using molecular mass as the sole indicator of protein size, have given contradictory results about the exclusion limits of the cyst nematode feeding tube. In this study we propose a method to predict protein size, based on protein database coordinates in silico. We tested the validity of these predictions using travelling wave ion mobility spectrometry--mass spectrometry, where predictions and measured values were within approximately 6%. We used the predictions, coupled with mass spectrometry, analytical ultracentrifugation and protein electrophoresis, to resolve previous conflicts and define the exclusion characteristics of the cyst nematode feeding tube. Heterogeneity was tested in the liquid, solid and gas phase to provide a comprehensive evaluation of three proteins of particular interest to feeding tube size exclusion, GFP, mRFP and Dual PI. The data and procedures described here could be applied to the design of plant expressed defence compounds intended for uptake into cyst nematodes. We also highlight the need to assess protein heterogeneity when creating novel fusion proteins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0087289PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905015PMC
November 2014

Identification of genes involved in the response of Arabidopsis to simultaneous biotic and abiotic stresses.

Plant Physiol 2013 Aug 25;162(4):2028-41. Epub 2013 Jun 25.

Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.

In field conditions, plants may experience numerous environmental stresses at any one time. Research suggests that the plant response to multiple stresses is different from that for individual stresses, producing nonadditive effects. In particular, the molecular signaling pathways controlling biotic and abiotic stress responses may interact and antagonize one another. The transcriptome response of Arabidopsis (Arabidopsis thaliana) to concurrent water deficit (abiotic stress) and infection with the plant-parasitic nematode Heterodera schachtii (biotic stress) was analyzed by microarray. A unique program of gene expression was activated in response to a combination of water deficit and nematode stress, with 50 specifically multiple-stress-regulated genes. Candidate genes with potential roles in controlling the response to multiple stresses were selected and functionally characterized. RAPID ALKALINIZATION FACTOR-LIKE8 (AtRALFL8) was induced in roots by joint stresses but conferred susceptibility to drought stress and nematode infection when overexpressed. Constitutively expressing plants had stunted root systems and extended root hairs. Plants may produce signal peptides such as AtRALFL8 to induce cell wall remodeling in response to multiple stresses. The methionine homeostasis gene METHIONINE GAMMA LYASE (AtMGL) was up-regulated by dual stress in leaves, conferring resistance to nematodes when overexpressed. It may regulate methionine metabolism under conditions of multiple stresses. AZELAIC ACID INDUCED1 (AZI1), involved in defense priming in systemic plant immunity, was down-regulated in leaves by joint stress and conferred drought susceptibility when overexpressed, potentially as part of abscisic acid-induced repression of pathogen response genes. The results highlight the complex nature of multiple stress responses and confirm the importance of studying plant stress factors in combination.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1104/pp.113.222372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3729780PMC
August 2013

Syncytia formed by adult female Heterodera schachtii in Arabidopsis thaliana roots have a distinct cell wall molecular architecture.

New Phytol 2012 Oct 17;196(1):238-246. Epub 2012 Jul 17.

Centre for Plant Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.

• Plant-parasitic cyst nematodes form a feeding site, termed a syncytium, through which the nematode obtains nutrients from the host plant to support nematode development. The structural features of cell walls of syncytial cells have yet to be elucidated. • Monoclonal antibodies to defined glycans and a cellulose-binding module were used to determine the cell wall architectures of syncytial and surrounding cells in the roots of Arabidopsis thaliana infected with the cyst nematode Heterodera schachtii. • Fluorescence imaging revealed that the cell walls of syncytia contain cellulose and the hemicelluloses xyloglucan and heteromannan. Heavily methyl-esterified pectic homogalacturonan and arabinan are abundant in syncytial cell walls; galactan could not be detected. This is suggestive of highly flexible syncytial cell walls. • This work provides important information on the structural architecture of the cell walls of this novel cell type and reveals factors that enable the feeding site to perform its functional requirements to support nematode development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1469-8137.2012.04238.xDOI Listing
October 2012

Transgenic potatoes for potato cyst nematode control can replace pesticide use without impact on soil quality.

PLoS One 2012 16;7(2):e30973. Epub 2012 Feb 16.

Centre for Plant Sciences, University of Leeds, Leeds, United Kingdom.

Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode) for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030973PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3281046PMC
August 2012

Strategies for transgenic nematode control in developed and developing world crops.

Curr Opin Biotechnol 2012 Apr 11;23(2):251-6. Epub 2011 Oct 11.

Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.

Nematodes cause an estimated $118b annual losses to world crops and they are not readily controlled by pesticides or other control options. For many crops natural resistance genes are unavailable to plant breeders or progress by this approach is slow. Transgenic plants can provide nematode resistance for such crops. Two approaches have been field trialled that control a wide range of nematodes by either limiting use of their dietary protein uptake from the crop or by preventing root invasion without a direct lethality. In addition, RNA interference increasingly in tandem with genomic studies is providing a range of potential resistance traits that involve no novel protein production. Transgenic resistance can be delivered by tissue specific promoters to just root tissues where most economic nematodes invade and feed rather than the harvested yield. High efficacy and durability can be provided by stacking nematode resistance traits including any that natural resistance provides. The constraints to uptake centre on market acceptance and not the availability of appropriate biotechnology. The need to deploy nematode resistance is intensifying with loss of pesticides, an increased need to protect crop profit margins and in many developing world countries where nematodes severely damage both commodity and staple crops.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.copbio.2011.09.004DOI Listing
April 2012

Effective delivery of a nematode-repellent peptide using a root-cap-specific promoter.

Plant Biotechnol J 2011 Feb;9(2):151-61

Centre for Plant Sciences, University of Leeds, Leeds, UK.

The potential of the MDK4-20 promoter of Arabidopsis thaliana to direct effective transgenic expression of a secreted nematode-repellent peptide was investigated. Its expression pattern was studied in both transgenic Arabidopsis and Solanum tuberosum (potato) plants. It directed root-specific β-glucuronidase expression in both species that was chiefly localized to cells of the root cap. Use of the fluorescent timer protein dsRED-E5 established that the MDK4-20 promoter remains active for longer than the commonly used constitutive promoter CaMV35S in separated potato root border cells. Transgenic Arabidopsis lines that expressed the nematode-repellent peptide under the control of either AtMDK4-20 or CaMV35S reduced the establishment of the beet cyst nematode Heterodera schachtii. The best line using the AtMDK4-20 promoter displayed a level of resistance >80%, comparable to that of lines using the CaMV35S promoter. In transgenic potato plants, 94.9 ± 0.8% resistance to the potato cyst nematode Globodera pallida was achieved using the AtMDK4-20 promoter, compared with 34.4 ± 8.4% resistance displayed by a line expressing the repellent peptide from the CaMV35S promoter. These results establish the potential of the AtMDK4-20 promoter to limit expression of a repellent peptide whilst maintaining or even improving the efficacy of the cyst-nematode defence.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1467-7652.2010.00542.xDOI Listing
February 2011

Identification and functional characterization of effectors in expressed sequence tags from various life cycle stages of the potato cyst nematode Globodera pallida.

Mol Plant Pathol 2009 Nov;10(6):815-28

Plant Pathology Programme, SCRI, Invergowrie, Dundee DD2 5DA, UK.

In this article, we describe the analysis of over 9000 expressed sequence tags (ESTs) from cDNA libraries obtained from various life cycle stages of Globodera pallida. We have identified over 50 G. pallida effectors from this dataset using bioinformatics analysis, by screening clones in order to identify secreted proteins up-regulated after the onset of parasitism and using in situ hybridization to confirm the expression in pharyngeal gland cells. A substantial gene family encoding G. pallida SPRYSEC proteins has been identified. The expression of these genes is restricted to the dorsal pharyngeal gland cell. Different members of the SPRYSEC family of proteins from G. pallida show different subcellular localization patterns in plants, with some localized to the cytoplasm and others to the nucleus and nucleolus. Differences in subcellular localization may reflect diverse functional roles for each individual protein or, more likely, variety in the compartmentalization of plant proteins targeted by the nematode. Our data are therefore consistent with the suggestion that the SPRYSEC proteins suppress host defences, as suggested previously, and that they achieve this through interaction with a range of host targets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1364-3703.2009.00585.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6640342PMC
November 2009

Functional characterisation of a cyst nematode acetylcholinesterase gene using Caenorhabditis elegans as a heterologous system.

Int J Parasitol 2009 Jun;39(7):849-58

Centre for Plant Sciences, University of Leeds, Leeds, UK.

Migration of plant-parasitic nematode infective larval stages through soil and invasion of roots requires perception and integration of sensory cues culminating in particular responses that lead to root penetration and parasite establishment. Components of the chemoreceptive neuronal circuitry involved in these responses are targets for control measures aimed at preventing infection. Here we report, to our knowledge, the first isolation of cyst nematode ace-2 genes encoding acetylcholinesterase (AChE). The ace-2 genes from Globodera pallida (Gp-ace-2) and Heterodera glycines (Hg-ace-2) show homology to ace-2 of Caenorhabditis elegans (Ce-ace-2). Gp-ace-2 is expressed most highly in the infective J2 stage with lowest expression in the early parasitic stages. Expression and functional analysis of the Globodera gene were carried out using the free-living nematode C. elegans in order to overcome the refractory nature of the obligate parasite G. pallida to many biological studies. Caenorhabditis elegans transformed with a GFP reporter construct under the control of the Gp-ace-2 promoter exhibited specific and restricted GFP expression in neuronal cells in the head ganglia. Gp-ACE-2 protein can functionally complement its C. elegans homologue. A chimeric construct containing the Ce-ace-2 promoter region and the Gp-ace-2 coding region and 3' untranslated region was able to restore a normal phenotype to the uncoordinated C. elegans double mutant ace-1;ace-2. This study demonstrates conservation of AChE function and expression between free-living and plant-parasitic nematode species, and highlights the utility of C. elegans as a heterologous system to study neuronal aspects of plant-parasitic nematode biology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijpara.2008.12.007DOI Listing
June 2009

Nematode resistance.

New Phytol 2008 28;180(1):27-44. Epub 2008 Jun 28.

Centre for Plant Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.

Plant-parasitic nematodes are major pests of both temperate and tropical agriculture. Many of the most damaging species employ an advanced parasitic strategy in which they induce redifferentiation of root cells to form specialized feeding structures able to support nematode growth and reproduction over several weeks. Current control measures, particularly in intensive agriculture systems, rely heavily on nematicides but alternative strategies are required as effective chemicals are withdrawn from use. Here, we review the different approaches that are being developed to provide resistance to a range of nematode species. Natural, R gene-based resistance is currently exploited in traditional breeding programmes and research is ongoing to characterize the molecular basis for the observed resistant phenotypes. A number of transgenic approaches hold promise, the best described being the expression of proteinase inhibitors to disrupt nematode digestion. The application of plant-delivered RNA interference (RNAi) to silence essential nematode genes has recently emerged as a potentially valuable resistance strategy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1469-8137.2008.02508.xDOI Listing
November 2008

Recent progress in the development of RNA interference for plant parasitic nematodes.

Mol Plant Pathol 2007 Sep;8(5):701-11

Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.

SUMMARY RNA interference (RNAi), first described for Caenorhabditis elegans, has emerged as a powerful gene silencing tool for investigating gene function in a range of organisms. Recent studies have described its application to plant parasitic nematodes. Genes expressed in a range of cell types are silenced when preparasitic juvenile nematodes take up double-stranded (ds)RNA that elicits a systemic RNAi response. Important developments over the last year have shown that in planta expression of a dsRNA targeting a nematode gene can successfully induce silencing in parasitizing nematodes. When the targeted gene has an essential function, a resistance effect is observed paving the way for the potential use of RNAi technology to control plant parasitic nematodes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1364-3703.2007.00422.xDOI Listing
September 2007

Differential gene expression in Arabidopsis following infection by plant-parasitic nematodes Meloidogyne incognita and Heterodera schachtii.

Mol Plant Pathol 2007 Sep;8(5):595-609

Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.

SUMMARY Whole genome microarrays were used to study plant gene expression in mature Meloidogyne incognita-induced galls in Arabidopsis. We found 959 genes to be significantly differentially expressed, and two-thirds of these were down-regulated. Microarray results were confirmed by qRT-PCR. The temporal and spatial responses of four differentially expressed genes were analysed using GUS reporter plants following infection with M. incognita and the cyst nematode Heterodera schachtii. The ammonium transporter gene AtAMT1;2 was consistently and locally repressed in response to both nematodes at all developmental stages. The lateral organ boundary domain gene LBD41 showed up-regulation in the feeding sites of both nematode species, although there was variation in expression in saccate H. schachtii female feeding sites. Expression of an actin depolymerizing factor ADF3 and a lipid transfer protein was induced in feeding sites of both nematodes at the fusiform stage and this persisted in feeding sites of saccate M. incognita. These results contribute to the knowledge of how plant gene expression responds to parasitism by these nematodes as well as highlighting further differences in the mechanisms of development and maintenance of these feeding site structures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1364-3703.2007.00416.xDOI Listing
September 2007

Preferential expression of a plant cystatin at nematode feeding sites confers resistance to Meloidogyne incognita and Globodera pallida.

Plant Biotechnol J 2004 Jan;2(1):3-12

Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.

The expression patterns of three promoters preferentially active in the roots of Arabidopsis thaliana have been investigated in transgenic potato plants in response to plant parasitic nematode infection. Promoter regions from the three genes, TUB-1, ARSK1 and RPL16A were linked to the GUS reporter gene and histochemical staining was used to localize expression in potato roots in response to infection with both the potato cyst nematode, Globodera pallida and the root-knot nematode, Meloidogyne incognita. All three promoters directed GUS expression chiefly in root tissue and were strongly up-regulated in the galls induced by feeding M. incognita. Less activity was associated with the syncytial feeding cells of the cyst nematode, although the ARSK1 promoter was highly active in the syncytia of G. pallida infecting soil grown plants. Transgenic potato lines that expressed the cystatin OcIDeltaD86 under the control of the three promoters were evaluated for resistance against Globodera sp. in a field trial and against M. incognita in containment. Resistance to Globodera of 70 +/- 4% was achieved with the best line using the ARSK1 promoter with no associated yield penalty. The highest level of partial resistance achieved against M. incognita was 67 +/- 9% using the TUB-1 promoter. In both cases this was comparable to the level of resistance achieved using the constitutive cauliflower mosaic virus 35S (CaMV35S) promoter. The results establish the potential for limiting transgene expression in crop plants whilst maintaining efficacy of the nematode defence.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1046/j.1467-7652.2003.00037.xDOI Listing
January 2004