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1
Sekora, Nicholas Scott Lawrence Katheryn Kay Scott. "Identification of plant-parasitic nematodes using FAME analysis." Auburn, Ala, 2009. http://hdl.handle.net/10415/1806.
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2
Nobbs, J. M. "The distribution and abundance of nematodes (especially the plant parasites) in the arid region of South Australia /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phn744.pdf.
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3
Pelinganga, Osvaldo Manuel. "Developing phytonematicides using indigenous cucumis africanus and cucumis myriocarpus fruits for tomatoproduction systems." Thesis, University of Limpopo, 2013. http://hdl.handle.net/10386/1354.
Full textAbstract:
Thesis (Ph. D. Agriculture (Plant Protection)) -- University of Limpopo, 2013<br>Global withdrawal of synthetic fumigant and non-fumigant nematicides due to their ecounfriendly
impacts and high toxicity to non-target organisms, respectively, increased the
research and development of alternatives for managing population densities of plantparasitic
nematodes, particularly the root-knot (Meloidogyne species) nematodes.
Although Meloidogyne species had been managed using genotypes that are resistant to
plant-parasitic nematodes in various crops, various challenges negate the available or
introgressed nematode resistance. In tomato (Solanum lycopersicum) production,
nematode races and instability of nematode resistant genotypes under certain
conditions necessitated the continued research and development of alternatives since
most of the existing commercial tomato cultivars are highly susceptible to various
biological races of Meloidogyne species. The aim of the study was to research and
develop appropriate dosages of two phyto- nematicides which could be applied through
drip irrigation system in open field tomato production systems, while the specific
objectives were to: (1) determine whether a computer-based model could provide nonphytotoxic
concentrations to tomato plants using fresh fruits of wild watermelon
(Cucumis africanus) and wild cucumber (C. myriocarpus) under greenhouse conditions,
(2) determine whether computer-based concentrations from the two plant species when
using dried fruits would be less phytotoxic and more suppressive to nematodes, (3)
investigate application time intervals for the two products, (4) determine responses of
plant growth in tomato and nematode suppression in respect to the derived dosages,
and and (5) validate dosages of fermented crude extracts from the two plant species
with respect to plant growth of tomato and suppression of nematode numbers.
xxxiii
Greenhouse, microplot and field studies were set to test the hypotheses intended to
achieve the stated objectives, with reliability of measured variables being ensured by
using statistical levels of significance (P ≤ 0.05) and coefficients of determination (R2),
while validity was ensured by conducting experiments at the same location over two
seasons and/or by setting up factorial treatments. Firstly, fermented plant extracts of
fresh fruits from C. africanus and C. myriocarpus consistently reduced population
densities of Meloidogyne species by 80-92% and 50-90%, respectively. Tomato plants
were highly sensitive to the two products as shown by the total degree of sensitivities
(Σk) and biological index of 0 and 3, respectively. Also, the mean concentration
stimulation range (MCSR) of 11% and 7% concentrations, respectively, attested to this
phytotoxicity. Secondly, fermented crude extracts of dried fruits from C. africanus and C.
myriocarpus also reduced population densities of Meloidogyne species by 78-97% and
87-97%, respectively. Tomato plants were highly tolerant to the two products in dried
form as shown by the total degree of sensitivities (Σk) and biological index of 4 and 3,
respectively. The MCSR values for C. africanus and C. myriocarpus dried fruits on
tomato were 2.64% and 2.99%, respectively, which for the purpose of this study were
individually adjusted to 3%, which translated to 36 L undiluted material/ha of 4 000
tomato plants. In subsequent studies, 3% concentration was used as the standard,
along with double strength concentration, namely, 6% concentration. Thirdly, the MCSR
values derived in Objective 4, namely 3% and 6% concentration for both Cucumis
species using the CARD model were used in the optimisation of application time interval
using the innovative concept of weeks (0, 1, 2, 3 and 4) in a 30-day month period.
Application time interval for 3% and 6% concentrations of C. africanus fruits was
xxxiv
optimised at 2.40 and 2.61 weeks in a 30-day month period, respectively, which
translated to 18 days [(2.4 weeks/4 weeks) × 30 days] and 20 days [(2.6 weeks/4
weeks) × 30 days], respectively. In contrast, for both concentrations from fermented
crude extracts of C. myriocarpus fruits, application time interval was optimised at 16
days for 2.2 and 2.1 weeks, respectively. During optimisation of application frequencies,
fermented crude extracts from C. africanus and C. myriocarpus reduced final population
densities of M. incognita race 2 by 70-97% and 76-96%, respectively. Fourthly, optimum
application intervals (time), allowed computation of dosage, which is a product of
concentration and application frequency (dosage = concentration × application
frequency). Fifthly, validation of the dosages under open field conditions suggested that
6% × 16-day dosage under crude extracts from C. myriocarpus fruit significantly (P ≤
0.05) improved growth of tomato plants when compared with those of either 0%
(untreated control) or 3% at 16 days. In contrast, dosages of C. africanus fruit at two
application frequency had no effect on growth of tomato plants – suggesting that either
of the dosages was suitable for use in tomato production since both reduced nematode
numbers. During validation, the materials reduced nematode numbers by margins
similar to those observed previously under other environments. In conclusion, crude
extracts of the two Cucumis species have stimulatory concentrations which have
potential similar reductive effects on population densities of Meloidogyne species and
could serve as botanical nematicides. However, since plant responses to the two
products differed in terms of their respective dosages and active ingredients, it implied
that for further improvement of the two, the overriding focus should be on their
interaction with the protected plants and nematode numbers. Ideally, future research
xxxv
should include environmental impact studies, especially on the influence of the products
fruit quality of tomato, earthworms, fish and bees.
4
Pelinganga, Osvaldo Manuel. "Developing phytonematicides using indigenous cucumis africanus and cucumis myriocarpus fruits for tomato production systems." Thesis, University of Limpopo, Turfloop Campus, 2013. http://hdl.handle.net/10386/1286.
Full textAbstract:
Thesis (Ph. D. Agriculture (Plant Protection)) -- University of Limpopo, 2013<br>Global withdrawal of synthetic fumigant and non-fumigant nematicides due to their ecounfriendly
impacts and high toxicity to non-target organisms, respectively, increased the
research and development of alternatives for managing population densities of plantparasitic
nematodes, particularly the root-knot (Meloidogyne species) nematodes.
Although Meloidogyne species had been managed using genotypes that are resistant to
plant-parasitic nematodes in various crops, various challenges negate the available or
introgressed nematode resistance. In tomato (Solanum lycopersicum) production,
nematode races and instability of nematode resistant genotypes under certain
conditions necessitated the continued research and development of alternatives since
most of the existing commercial tomato cultivars are highly susceptible to various
biological races of Meloidogyne species. The aim of the study was to research and
develop appropriate dosages of two phyto- nematicides which could be applied through
drip irrigation system in open field tomato production systems, while the specific
objectives were to: (1) determine whether a computer-based model could provide nonphytotoxic
concentrations to tomato plants using fresh fruits of wild watermelon
(Cucumis africanus) and wild cucumber (C. myriocarpus) under greenhouse conditions,
(2) determine whether computer-based concentrations from the two plant species when
using dried fruits would be less phytotoxic and more suppressive to nematodes, (3)
investigate application time intervals for the two products, (4) determine responses of
plant growth in tomato and nematode suppression in respect to the derived dosages,
and and (5) validate dosages of fermented crude extracts from the two plant species
with respect to plant growth of tomato and suppression of nematode numbers.
xxxiii
Greenhouse, microplot and field studies were set to test the hypotheses intended to
achieve the stated objectives, with reliability of measured variables being ensured by
using statistical levels of significance (P ≤ 0.05) and coefficients of determination (R2),
while validity was ensured by conducting experiments at the same location over two
seasons and/or by setting up factorial treatments. Firstly, fermented plant extracts of
fresh fruits from C. africanus and C. myriocarpus consistently reduced population
densities of Meloidogyne species by 80-92% and 50-90%, respectively. Tomato plants
were highly sensitive to the two products as shown by the total degree of sensitivities
(Σk) and biological index of 0 and 3, respectively. Also, the mean concentration
stimulation range (MCSR) of 11% and 7% concentrations, respectively, attested to this
phytotoxicity. Secondly, fermented crude extracts of dried fruits from C. africanus and C.
myriocarpus also reduced population densities of Meloidogyne species by 78-97% and
87-97%, respectively. Tomato plants were highly tolerant to the two products in dried
form as shown by the total degree of sensitivities (Σk) and biological index of 4 and 3,
respectively. The MCSR values for C. africanus and C. myriocarpus dried fruits on
tomato were 2.64% and 2.99%, respectively, which for the purpose of this study were
individually adjusted to 3%, which translated to 36 L undiluted material/ha of 4 000
tomato plants. In subsequent studies, 3% concentration was used as the standard,
along with double strength concentration, namely, 6% concentration. Thirdly, the MCSR
values derived in Objective 4, namely 3% and 6% concentration for both Cucumis
species using the CARD model were used in the optimisation of application time interval
using the innovative concept of weeks (0, 1, 2, 3 and 4) in a 30-day month period.
Application time interval for 3% and 6% concentrations of C. africanus fruits was
xxxiv
optimised at 2.40 and 2.61 weeks in a 30-day month period, respectively, which
translated to 18 days [(2.4 weeks/4 weeks) × 30 days] and 20 days [(2.6 weeks/4
weeks) × 30 days], respectively. In contrast, for both concentrations from fermented
crude extracts of C. myriocarpus fruits, application time interval was optimised at 16
days for 2.2 and 2.1 weeks, respectively. During optimisation of application frequencies,
fermented crude extracts from C. africanus and C. myriocarpus reduced final population
densities of M. incognita race 2 by 70-97% and 76-96%, respectively. Fourthly, optimum
application intervals (time), allowed computation of dosage, which is a product of
concentration and application frequency (dosage = concentration × application
frequency). Fifthly, validation of the dosages under open field conditions suggested that
6% × 16-day dosage under crude extracts from C. myriocarpus fruit significantly (P ≤
0.05) improved growth of tomato plants when compared with those of either 0%
(untreated control) or 3% at 16 days. In contrast, dosages of C. africanus fruit at two
application frequency had no effect on growth of tomato plants – suggesting that either
of the dosages was suitable for use in tomato production since both reduced nematode
numbers. During validation, the materials reduced nematode numbers by margins
similar to those observed previously under other environments. In conclusion, crude
extracts of the two Cucumis species have stimulatory concentrations which have
potential similar reductive effects on population densities of Meloidogyne species and
could serve as botanical nematicides. However, since plant responses to the two
products differed in terms of their respective dosages and active ingredients, it implied
that for further improvement of the two, the overriding focus should be on their
interaction with the protected plants and nematode numbers. Ideally, future research
xxxv
should include environmental impact studies, especially on the influence of the products
fruit quality of tomato, earthworms, fish and bees.
5
Jordan, Katerina Serlemitsos. "The ecology of plant-parasitic nematodes and their antagonists on golf course greens turf in southern New England /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3188061.
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6
Soriano, Imelda Rizalina. "Novel inducible phytochemical defences against plant parasitic nematodes /." Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phs7141.pdf.
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7
Soomro, M. H. "The effects of plant parasitic nematodes and plant growth regulators on root growth of graminacious plants." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378682.
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8
Briar, Shabeg Singh. "Nematodes as bioindicators of soil food web health in agroecosystems a critical analysis /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1173284523.
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9
KC, Ashmit. "Plant-Parasitic Nematodes on Sugarbeet in North Dakota and Minnesota." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/29884.
Full textAbstract:
Field surveys were conducted in the Red River Valley (RRV) of North Dakota and Minnesota during 2016 and 2017 to determine the incidence, abundance, and distribution of plant-parasitic nematodes (PPNs) on sugarbeet. Seventy-two and 65 % of the fields surveyed were positive for PPNs in 2016 and 2017, respectively. The major genera of PPNs identified from sugarbeet production fields were Heterodera, Helicotylenchus, Tylenchorhynchus, Paratylenchus, Pratylenchus, Paratrichodorus, Hoplolaimus, and Xiphinema. Eight of PPNs were identified at the species level using species-specific PCR assays, and sequencing of the ribosomal rDNA gene. Stubby-root nematode, Paratrichodorus allius, is one of the important nematode pests for sugarbeet production worldwide. An experiment was conducted to determine the host status of sugarbeet and their rotational crops for P. allius under greenhouse conditions. The results from two experiments indicated sugarbeet and most rotational crops support the reproduction of P. allius.<br>Sugarbeet Research and Education Board (Minn.)<br>Sugarbeet Research and Education Board (N.D.)<br>American Crystal Sugar Company
10
Upadhaya, Arjun. "Plant-Parasitic Nematodes in Field Pea and Potato and their Effect on Plant Growth and Yield." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28875.
Full textAbstract:
In this study, surveys were conducted in pea and potato fields in North Dakota and Central Minnesota to investigate the incidence and abundance of plant-parasitic nematodes in these fields. Moreover, the effect of the pin nematode, Paratylenchus nanus, on plant growth and yield of six field pea cultivars was determined under greenhouse conditions. Similarly, the influence of lesion nematode, Pratylenchus penetrans, and wilt fungi, Fusarium oxysporum alone and together on growth and yield of potato cultivar ‘Red Norland’, was evaluated in microplots under field conditions. The results indicate Paratylenchus spp. and Pratylenchus spp. are the most frequent nematodes, respectively, in pea and potato fields. Pin nematodes reproduced on field pea cultivars and caused up to 37% reduction in plant height and 40% reduction in yield. Additionally, both P. penetrans and F. oxysporum alone, and together had significant negative effect on growth and yield of potato.
11
Mahdy, Magdy. "Biological control of plant parasitic nematodes with antagonistic bacteria on different host plants." Bonn : Rheinische Friedrick-Wilhelms-Universität, Institut für Pflanzenkrankheiten, 2002. http://hss.ulb.uni-bonn.de/ulb_bonn/diss_online/landw_fak/2002/mahdy_magdy/0203.pdf.
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12
McMaster, S. "Studies on Gene Silencing in Plant Parasite Nematodes." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501370.
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13
Rossi, Carlos Eduardo. "Levantamento, reprodução e patogenicidade de nematóides a fruteiras de clima subtropical e temperado." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-04092002-170644/.
Full textAbstract:
Objetivando melhor conhecimento a respeito dos nematóides encontrados associados a fruteiras de clima subtropical e temperado, coletaram-se 149 amostras de solo da rizosfera e de raízes de amoreira-preta, caquizeiro, framboeseira, macieira, marmeleiro, nespereira, nogueira-macadâmia, oliveira, pereira, pessegueiro e umezeiro em áreas de produção do Estado de São Paulo e em uma localidade de Minas Gerais. Como resultado desse levantamento, identificaram-se 11 gêneros e as espécies relacionadas a seguir: Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense e Xiphinema spp.. Os três gêneros mais freqüentes foram Helicotylenchus, Mesocriconema e Xiphinema, presentes em 60,4; 55,0 e 30,2 % das amostras, respectivamente; as espécies mais comuns foram H. dihystera e M. xenoplax, ocorrendo em 49 e 38,3 % das amostras. Contudo, apenas M. incognita e M. javanica estavam associados a danos em pessegueiros cujos porta-enxertos não tinham resistência genética. Em casa de vegetação, avaliaram-se as reações de genótipos das citadas fruteiras, mais goiabeira, frente aos nematóides de galhas Meloidogyne incognita raça 2 e M. javanica. As plantas, individualmente inoculadas com 5000 ovos de cada espécie de nematóide, foram conduzidas em recipientes plásticos durante 120 dias. A caracterização das reações baseou-se na capacidade reprodutiva dos parasitos, determinando-se os índices de massas de ovos e de galhas, bem como os números de nematóides por sistema radicular e por grama de raízes. Apenas a cultivar GF-677 de Prunus persica x P. dulcis comportou-se como suscetível, possibilitando desenvolvimento e multiplicação dos dois nematóides. Os demais genótipos avaliados foram hospedeiros desfavoráveis ao desenvolvimento dos nematóides, sendo considerados resistentes, embora vários deles tivessem proporcionado restritas taxas de reprodução dos parasitos. Estudou-se ainda, também sob condição de casa de vegetação, a patogenicidade de M. incognita raça 2 em caquizeiro 'Kyoto', verificando-se correlação negativa entre os níveis populacionais iniciais utilizados (0, 160, 800, 4 000, 20 000 e 100 000 ovos por parcela) e a altura e a massa seca de raízes das plantas, após seis meses da inoculação. Tendo em vista que a intensa formação de galhas radiculares observada e o efeito negativo sobre os dois parâmetros de crescimento das plantas mostraram-se associados a taxas de reprodução muito baixas do parasito, considerou-se que a reação ocorrida foi de intolerância.<br>In order to achieve a better knowledge on the nematodes found associated with subtropical and temperate fruits, a total amount of 149 soil and root samples were collected from within apple, blackberry, japanese apricot, loquat, macadamia, olive, peach, pear, persimmon, quince and raspberry orchards located in the states of São Paulo and Minas Gerais, Southeastern Brazil. From this survey, a number of species belonging to eleven genera were identified, namely Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense and Xiphinema spp. The most frequent genera were Helicotylenchus, Mesocriconema and Xiphinema, which occurred in 60.4, 54.4 and 30.2 % of the samples, respectively; the two most common species found were Helicotylenchus dihystera and Mesocriconema xenoplax, detected in 49.0 and 38.8 % of the samples, respectively. However, only Meloidogyne incognita and M. javanica could be associated with peach trees that were stunted or showed general symptoms of decline; in these cases, the rootstocks did not have genetic resistance to root-knot nematodes. The host suitability of several genotypes of the mentioned fruit species, plus guava, were evaluated in relation to Meloidogyne incognita race 2 and M. javanica under greenhouse conditions. The plants were individually inoculated with 5,000 nematode eggs and kept to grow in plastic bags for four months. Nematode reproductive rate was determined with basis on gall index, egg mass index and numbers of nematodes per root system and per gram of roots. Only the cultivar GF-677 of Prunus persica x P. dulcis was susceptible to both nematode species. All other genotypes were poor/resistant hosts, even that some allowed the parasites to reproduce at low rates. The pathogenicity of Meloidogyne incognita race 2 to persimmon cv. Kyoto was also studied under greenhouse conditions. After six months of the inoculation with increasing nematode population levels 0; 160; 800; 4,000; 20,000; and 100,000 eggs/plant a negative correlation with plant height and top dry weight values was obtained. As an intense root galling was associated with low nematode reproductive rates and some depressive effects on the plant growth, the reaction was rated as being of intolerance.
14
Costa, Joana Cristina. "The neurobiology and chemoreception in plant-parasitic nematodes." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493557.
Full textAbstract:
Comparative genomics of shared processes can provide insights into plant-parasitic nematode biology that would otherwise be intractable. Caenorhabditis elegans, together with the information and resources available for this model species, was used in Globodera pallida. This cyst nematode infects potato plants and is considered an agricultural pest worldwide.
15
Goodchild, Sarah Ann. "Effective and durable resistance against plant parasitic nematodes." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396594.
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16
Vaid, Alka. "Application of molecular biological techniques to the study of Pasteuria penetrans, an obligate parasite of plant parasitic nematodes." Thesis, University of Greenwich, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286079.
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17
Gouge, D. H., K. A. Smith, C. Payne, L. L. Lee, Berkum J. R. Van, and T. J. Henneberry. "Suppression of Plant Parasitic Nematodes in Cotton Using the Antomopathogenic Nematode Steinernema Riobravis (Cabanillas, Poinar, and Raulston) (Rhabditida: Steinernematidae)." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/211150.
Full textAbstract:
Cotton fields were treated with the entomopathogenic nematode, Steinernema riobravis, and Vydate® L for the control of plant parasitic nematodes. Short staple cotton grown near Coolidge, Arizona, was treated at a rate of 1 billion and 2 billion S. riobravis nematodes per acre, and 0.5 lb a.i. Vydate® L per acre. Untreated cotton received an application of water only. Treatments were applied through a subterranean drip system with 12 inch spaced outlets. Applications were made in the daily irrigation cycle of 0.33 inches of water, normal irrigation cycles followed Products were uniformly distributed over the treated fields. Entomopathogenic nematodes persisted throughout the 6 week experimental period at the 1 billion per acre rate. However, nematodes applied at 2 billion per acre rate disappeared rapidly. Populations of various plant parasitic nematode species were monitored subsequent to treatment application. Nematodes were extracted using a standard sugar flotation technique and counted in I ml slide samples. Both Meloidogyne incognita and Tylenchorhynchus spp. populations were reduced by S. riobravis applied at 1 billion per acre rate. Phytoparasitic nematodes were reduced following application of Vydate® L, but control was not sustained beyond one week.
18
Patel, Nrupali. "Functional Analyses of Cyst Nematode Parasitism Genes." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-03102008-221413/.
Full textAbstract:
Cyst nematodes in the genus Heterodera are sedentary endoparasites that induce elaborate feeding cells within host roots by secreting proteins produced within nematode esophageal glands into plant cells. Functional analyses of selected cyst nematode parasitism genes that encode such secreted proteins was the objective of this dissertation. Homologs of four parasitism genes initially isolated from Heterodera glycines, including Hg4F01 (annexin-like protein), HgSYV46 (CLAVATA3-like plant peptide mimic), Hg4E02 and Hg5D08 (novel proteins with putative host nuclear localization) were isolated from Heterodera schachtii, which can infect Arabidopsis thaliana. Greater than 90% nucleotide and predicted amino acid identity existed between the four parasitism genes homologs of H. glycines and H. schachtii. mRNA in situ hybridization and immunolocalization confirmed the expression of each gene product exclusively within the nematode esophageal gland cells. Since eukaryotic annexins affect many cellular processes involving calcium-dependent membrane association, the potential function of the Hs4F01 secreted into plant cells was analyzed. Similar to annexin mutants in Arabidopsis, transgenic Arabidopsis expressing Hs4F01 produced no observable plant phenotype, but were more susceptible to nematode infection. Hypersensitivity to osmotic stress in an Arabidopsis annAt1 annexin mutant was reduced (complemented) in mutants that expressed Hs4F01, suggesting a functional similarity of nematode and plant annexins within plant cells. Host derived RNA interference (RNAi) to silence Hs4F01 transcripts significantly reduced the number of H. schachtii females developing on roots that express dsRNA to Hs4F01. Expression of Hs4E02 and Hs5D08 in Arabidopsis produced no observable plant phenotype and susceptibility to H. schachtii was not altered in plants that expressed Hs4E02. Silencing of HsSYV46 using host-derived RNAi demonstrated a significant reduction in the development of nematode females on Arabidopsis roots that expressed double-stranded RNA to HsSYV46. Expression of dsRNA to Hs4E02 and Hs5D08 in Arabidopsis roots did not affect nematode susceptibility. In summary, parasitism gene products confirmed to have cellular functions similar to their plant homologs, including Hs4F01 (annexin-like protein) and HsSYV46 (CLAVATA/ESR-like peptide) were demonstrated by RNAi to have a significant biological role in cyst nematode parasitism of host plant roots.
19
Youssef, Banora Mohamed. "The plant cystoskeleton : target for plant parasitic nematodes during a susceptible interaction." Nice, 2010. http://www.theses.fr/2010NICE4055.
Full textAbstract:
Les nématodes à galles du genre Méloidogyne ou « root-knot nematodes (RKN) », sont de redoutables endoparasites sédentaires obligatoires de nombreuses espèces végétales. Ils sont capables d’engendrer de profondes modifications au niveau des cellules racinaires, en induisant la formation de structures nourricières spécifiques. Ces cellules vasculaires des racines évoluent en cellules nourricières géantes complexes (cellules géantes) qui fournissent les nutriments indispensables à la croissance, la sédentarisation et le développement des nématodes jusqu’au stade adulte fertile. Les cellules géantes sont acytokinétiques, multinucléées et hypertrophiées. Leur cytoplasme est dense et présente une intense activité métabolique. Les organites qu’il renferme prolifèrent abondamment. L’actine et le cytosquelette microtubulaire sont totalement réarrangés. Par conséquent, le cytosquelette de la cellule végétale pourrait être l’une des principales cibles d’action du nématode au moment de l’infection et sa réorganisation semble être une étape majeure pour la réussite du cycle de vie du parasite. Afin de savoir quel rôle joue le cytosquelette lors de la croissance isodiamétrique des cellules nourricières et quels sont les composants du cytosquelette impliqués dans la mise en place des sites d’alimentation du nématode ou « nematode feeding sites (NFS) », nous avons entrepris l’étude de la répartition et du réarrangement des microtubules du cytosquelette tout au long du développement des cellules géantes. L’analyse immunocytochimique des tubulines ainsi que l’observation in vivo des microtubules (MT) décorées avec le GFP a mis en évidence d’importantes modifications du cytosquelette au cours du développement des cellules géantes. Nos résultats montrent clairement que les microtubules corticaux sont denses et apparemment désordonnés et que les MTs endoplasmiques subissent probablement une dépolymérisation partielle au cours de l’ontogénèse des cellules géantes. Par ailleurs on observe dans ces cellules de nombreux sites contenant des phragmoplastes non alignés lors d’événements mitotiques qui s’avèrent également incomplets. Ce réarrangement global du cytosquelette semble important pour l’initiation de la formation puis le développement des galles. Afin de mieux comprendre les réarrangements du cytosquelette qui apparaissent lors du développement des cellules nourricières, nous avons entrepris l’étude du rôle spécifique des y-tubulines dans la nucléation MT au niveau des centres d’organisation MT (MTOCs). L’analyse par RT-PCR quantitative a révélé, au niveau des NFS, une surexpression des transcrits des gènes des deux y-tubulines d’Arabidopsis (TUBG1 et TUBG2) ainsi que des gènes codant les protéines du complexe y-tubuline (GCP3 et GCP4). En utilisant des lignées mutantes pour les protéines du complexe y-tubuline, nous avons démontré que les deux y-tubulines (TUBG1 et TUBG2) sont nécessaires au bon développement des cellules nourricières et à la maturité des nématodes. Les analyses immunocytochimiques des racines d’Arabidopsis infectées par les nématodes ont montré que les y-tubulines GFPs sont abondamment présentes et localisées au niveau des phragmoplastes des cellules géantes et qu’elles y sont associées au MTs corticaux et cytosoliques. En outre, l’immunofluorescence des y-tubulines de lignées mutantes dans les racines infectées par les nématodes a indiqué que les y-tubulines protéines TUBG1 et TUBG2 n’ont pas la même localisation dans les cellules géantes : TUGB1 est fortement concentrée autour de la membrane nucléaire alors que TUBG2 est répartie dans l’ensemble du cortex cellulaire. Nous avons généré des plantes transgéniques exprimant la protéine de fusion y-tubuline-GFP et les observations in vivo du méristène apical des racines ont mis en évidence une répartition homogène de la protéine dans tout le cytoplasme, le cortex cellulaire et le long des fuseaux miotiques et des phragmoplastes pendant la mitose. Dans les cellules géantes, la y-tubuline est répartie principalement autour des noyaux avec une répartition régulière en tache. La surexpression de la y-tubuline a également provoqué une croissance incurvée des racines avec apparition d’un phénotype en forme de vrille. Le traitement avec des molécules chimiques actives sur le cytosquelette (propyzamide et oryzaline) a entraîné une réversion de ce phénotype vrillé et un retour à une croissance normale des racines, identique au type sauvage. Enfin, l’immunolocalisation réalisée en microscopie électronique a démontré que GCP3 est co-localisée avec la y-tubuline autour de la surface nucléaire et dans le cortex de la cellule géante. De ce fait l’existence d’une complexe de type « y-tubulin ring complex (yTuRC) » dans les cellules géantes est très vraisemblable. Ce travail suggère que la présence des MTOCs dans les cellules géantes pourrait être responsable d’un nouveau type de nucléation MT au niveau du cortex cellulaire, autour des noyaux et pendant la phase de mitose de cellules géantes induites par les nématodes à galles. Par conséquent, les y-tubulines semblent jouer un rôle important dans le contrôle de la restructuration du cytosquelette des cellules géantes induites par les nématodes<br>Root-knot nematode (RKN) Meloidogyne species are one of the most important obligate sedentary endoparasites attacking many plants species. They are competent to modify plant root cells by inducing specialized feeding structures. The genera Meloidogyne is capable to induce abnormal changes in selectes root vascular cells to form complex feeding cells (giant cells) that supply nutrients for the nematodes to enlarge, become sedentary and finally developing into fertile adults. Giant cells are hypertrophied multinucleated acytokinetic cells containing a dense metabolically active cytoplasm filled with proliferating organelles and showing an entirely rearranged actin and microtubular cytoskeleton. Therefore, the plant cytoskeleton might be one of the main targets during nematode infection and its rearrangement seems to be important for the successful completion of the nematode’s life cycle. In order to find out which role the cytoskeleton plays during the fast isodiametric growth of feeding cells and which cytoskeleton components are involved in the cytoskeletal remodelling of nematode feeding site (NFS), we investigated the distribution of the microtubular cytoskeleton and its behaviour during giant cell development. Immunocytochemical analysis of tubulins as well as in vivo observation of GFP-decorates microtubules (MT) revealed that severe changes of the cytoskeleton occur during feeding cell development. Our results provide evidence that cortical microtubules are dense and seemingly disordered and that endoplasmic MT’s probably undergo partial depolymerisation during giant cell ontogeny. On the other hand, large and multiple malformed spindles and phragmoplasts are seen in these giant feeding cells during (incomplete) mitotic events. The rearrangement of the cytoskeleton seems important for the proper initiation and development of galls,. In order to better understand the cytoskeleton rearrangement during feeding cell development we have initiated studies to investigate the involvement of y-tubulins which are required for MT nucleation at MT organizing centers (MTOCs). Our quantitative-RT-PCR analysis revealed that the transcripts of Arabidopsis y-tubulin genes (TUBG1 and TUBG2) and two y-tubulin complex proteins genes (GCP3 and GCP4) are upregulated in NFS. By using y-tubulin mutant lines, we demonstrated that both Arabidopsis y-Tubulins are needed for proper feeding cell development and nematode maturity. Immunocytochemical analyses of nematode infected Arabidopsis roots illustrated that y-tubulin-GFP are abundantly present in giant cells, localized to giant cell phragmoplasts and are associated with the cortical and cytosolic MTs. Furthermore, the immunofluorescence of y-tubulins in roots of nematode infected mutant lines indicated that y-tubulin proteins (TUBG1 and TUBG2) localize differently in giant cells : TUBG1 is highly concentrated around the nuclear surface of giant cell whereas TUBG2 is mainly distributed throughout the celle cortex. We have generated transgenic plants expressing the y-tubulin –GFP protein and in vivo observations of root apical meristem revealed abundant protein distributed throughout the cytoplasm and along spindles during mitosis. In giant cells y-tubulin was distributed mainly around the nuclei. Overexpression of y-tubulin also induced roots to skew and to adopt a twisted phenotype. Treatment with cytoskeleton drugs (propyzamide and oryzalin) showed that the twisted phenotype disappeared and roots grew traight as in wild type. Finally, immunolocalization carried out at the light and electron microscope level demonstrated that GCP3 colocalized with y-tubulin along the nuclear surface and in the giant cell cortex suggesting the presence of thze y-tubulin ring complex (yTuRC) in giant cells. This work suggests the presence of MTOCs in giant cells that might responsible for novel MT nucleation at the cell cortex, around the nuclei and during mitosis in giant-feeding cells induced by roots-knot nematodes. Therefore, y-tubulins may be play an important role in the control of cytoskeleton remodelling in nematode induced feeding cells
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Maboreke, Hazel Ruvimbo. "Effect of plant-parasitic nematodes on rhizosphere interactions in oaks." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17783.
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Diese Arbeit untersucht die Reaktion der Stieleiche auf pflanzenparasitären Nematoden mittels RNA-Sequenzierung und Analyse von stabilen Isotopen und Fettsäuren. Einblicke in Rhizosphäreninteraktionen wurden über mutualistische Partner (Ektomykorrhizapilze, Rhizosphärenhelferbakterien), fungivore Collembolen und multitrophische Gemeinschaften gewonnen. Die Struktur und Biomasse der Mikroorganismen sowie die Fitness der Eichen wurden erfasst. Die Effekte wurzelfressender Nematoden auf die Eiche wurden durch das endogene rhythmische Wachstum des Baumes reguliert. Die Nematoden lösten eine stärkere Reaktion während des Sprosswachstumsschubs aus, u.a. Aktivierung von Abwehrmechanismen und Hemmung der Photosynthese, wohingegen beim Wurzelwachstumsschub pathogen bezogene Signale unterdrückt waren. Die Anwesenheit des Pilzsymbionten schwächte die Pflanzenabwehr und verbesserte die Stresstoleranz, was indirekt das Wachstum der Mikroorganismen förderte. Die Helferbakterien begünstigten den Mykorrhizapilz, was wiederum das Pflanzenwachstum stimulierte und dem negativen Effekt der Nematoden entgegenwirkte. Parasitäre Nematoden und fungivore Collembolen beeinflussten die Verteilung des pflanzlichen Kohlenstoffes unabhängig voneinander; Nematoden verringerten und Collembolen verbesserten die Allokation von Photoassimilaten in Gram-postiven Bakterien. Zudem war steigende trophische Diversität der Bodenfauna in der Rhizosphäre entscheidend für die Balance innerhalb der mikrobiellen Gemeinschaft, welche das Pflanzenwachstum fördert. Diese Arbeit stellt die Bedeutung der endogenen Ressourcenzuteilung von Pflanzen für unterirdische biotische Wechselbeziehungen heraus. Diese Pflanzenstrategie als bedeutender Faktor für Rhizosphärenprozesse sollte in zukünftige Studien Berücksichtigung finden. Die Einbeziehung der Hauptakteure in der Rhizosphäre ermöglicht zudem ein realistischeres Bild von Nematoden-Pflanzen Interaktionen und damit ein effektiveres Management.<br>This thesis investigated the response of Pedunculate oak to the plant-parasitic nematode Pratylenchus penetrans, using RNA-sequencing, stable isotope labelling and fatty acid analyses. Insight into rhizosphere interactions was gained by employing beneficial biotic partners (ectomycorrhizal fungi, rhizosphere helper bacteria), fungal grazers (Collembola) and multitrophic environments. Microbial biomass and community structure as well as oak fitness were assessed. The effects of root-feeding nematodes on oak were largely governed by the endogenous rhythmic growth of the tree. The nematodes triggered a stronger response during shoot flush, e.g. activation of multi-layered defence mechanisms and repression of photosynthesis, as compared to root flush where pathogen-related signalling was repressed. With the presence of the mycorrhizal symbiont plant defence was attenuated and stress tolerance enhanced, indirectly promoting the growth of rhizosphere microorganisms. The helper bacteria fostered the ectomycorrhizal fungus, which in turn stimulated plant growth, counteracting the negative effects of nematodes. Plant-parasitic nematodes and Collembola grazers had independent roles in plant carbon allocation patterns, with nematodes hampering whilst Collembola enhancing the flux of recent photoassimilates to Gram-positive bacteria. Lastly, increasing trophic diversity of the soil fauna in the rhizosphere of oaks was crucial for the maintenances of a microbial community equilibrium that promotes plant growth. In sum, this study highlights the importance of endogenous resource allocation pattern of plants in determining the outcome of belowground biotic interactions. Therefore such plant traits should be considered as important drivers for rhizosphere processes in future studies. Moreover, taking into account the rhizosphere main players in studies on parasitic nematode-plant interactions will result in a more realistic picture and thus more effective nematode management.
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Dalzell, J. J. "The development of gene silencing strategies for plant parasitic nematodes." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546037.
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Zasada, Inga Anne. "Chemical components of the Brassicaceae that suppress plant-parasitic nematodes /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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MacCulloch, Laura A. "Chemotactic and electrotactic localisation of plant roots by parasitic nematodes." Thesis, University of Aberdeen, 1991. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU033780.
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The rhizosphere and rhizoplane environments of higher plant roots are specialised microhabitats for soil organisms. These organisms include nematodes which are capable of responding to attractants from roots over several centimetres (Rode, 1962, 1969). The aim of this project was to investigate the various aspects of chemotaxis in host finding by nematodes, and the relative importance of electrotaxis in this process. This involved experimentation on root diffusate as a whole, on various ions etc which may be attractive components of root diffusate, on interference by lectins on the host finding process and finally into nematode response to applied electrical fields with comparison to field strengths measured at root surfaces. The working hypothesis used throughout this project was the occurrence of long distance attraction via a non-specific factor which is replaced by a more specific factor as the distance between host and parasite is reduced. Examination of the diffusate as a whole clearly demonstrated that nematode attraction is a directed response. It also gave some support to the theory of successive attractive factors, with each successive factor being of higher molecular weight and lower diffusibility. The response to H+, OH-, Na+, five amino acids and cAMP was tested. The two pH extremes were equally attractive, the Na+ and amino acids were neither attractive nor repulsive and the cAMP was repulsive at the higher concentration used. These results suggested that the ions might have a secondary involvement in attraction by stimulating the initial movement of the nematodes but would be non-specific. Any attraction to amino acids noted by other workers e.g. Bird (1959) might be due to the acidic nature of the amino acids tested. Experiments were carried out using concanavalin A to interfere with host finding as suggested by Marban-Mendoza et al. (1987) through its effects on surface carbohydrates. The experiments produced some evidence to support this theory, and further experiments were made to try to elucidate the mechanism. The results from this further work indicate the effect in pH dependent via changes in aggregate size, but also that there may be a dilution involvement as well. Application of electrical fields to the nematodes produced directional movement, but at voltages approximately 1,000 times that measured at the root surfaces with the vibrating probe. It is therfore concluded that chemotaxis is the primary means by which nematodes locate their host plants, but the possibility of electrotaxis being used to locate specific feeding sites is discussed.
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Zaheer, Khalid. "Virulence and biochemical systematics of potato cyst-nematodes (PCN)." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334687.
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Davies, Laura Jane. "The role of auxin in plant-parasitic nematode interactions." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590663.
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The plant parasitic cyst nematode Heterodera schachtii forms a specialised feeding cell in the roots of host plants. The feeding site, termed a syncytium, is the sole source of nutrition for the developing parasitic nematode. The initiation and development of a syncytium requires extensive re-programming of gene expression in the specific root cells selected by the nematode for feeding site initiation. Auxin is postulated to playa role in this re-differentiation process. Activation of the auxin-responsive promoter DR5 in syncytia indicates an increase in perceived auxin levels. To determine whether or not the increase in auxin is required for the formation of syncytia, auxin signalling mutants were infected with H. schachrii for analysis of syncytial and nematode development. Measuring the size of syncytia throughout H schachtii development revealed sign ificantly smaller syncytia were formed in the auxin signalling mutant, axrl-12 in comparison to wild type plants. To elucidate biological processes mediated by auxin during syncytial development in silico analysis was performed on syncytia transcriptome data; this was used to identify genes upregulated in the syncytia that contain auxin-responsive elements in the promoter region. The cytoplasmic contents of syncytia formed in axrl -12 and wild type plants were microaspirated; this material was used for qRT-PCR analysis of auxin responsive gene expression. qRT-PCR analysis revealed that genes encoding cell wall remodelling enzymes were differentially expressed in syncytia fonned on axr 1-12 plants. The effects of altered cell wall remodelling enzyme expression on the structure of syncytia were investigated by obtaining transverse sections through syncytia fanned in wild type and axr 1-12 plants. Monoclonal antibodies to defined glycans and a cellulose binding module were used to localise carbohydrate and structural protein components in the cell walls of syncytia. The carbohydrate components of syncytia were found to be similar but differences were observed in the expression of structural proteins in syncytia formed in axr1-J2 and wild type plants. Additionally, cell wall degradation had occurred more extensively in syncytia formed in wild type plants in comparison to syncytia in axrJ·12. Cell proliferation in axrJ-12 and wild type roots during syncytial development was examined and found to be reduced in the auxin signalling mutant, indicating a role for auxin mediating cell-cyc\e activation during the development of syncytia. This study provides the first insight into the biological processes mediated by auxin during the development of syncytia by H schachtii in Arabidopsis thaliana .
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Ratnasoma, H. A. "Studies on the use of Pasteuria penetrans for control of root-knot nematodes and its field evaluation on perennial crops in Sri Lanka." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253457.
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Kashaija, Imelda Night. "Factors influencing nematode population densities and root damage on banana cultivars in Uganda." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309517.
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Oliver, J. F. "The effects of plant growth regulators and plant parasitic nematodes on cereal root growth." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233539.
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Walsh, Ellie Kathleen. "Investigating Root-Knot and Soybean Cyst Nematode Parasitic Interactions through Transcriptomic Analyses of the Host and Parasite." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471856126.
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Persidis, Aris. "The biochemistry of attachment of Pasteuria penetrans to plant-parasitic nematodes." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357861.
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Kerr, Rachel. "Novel control strategies for plant parasitic nematodes in sports amenity sites." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.679236.
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The phasing out of popular chemical nematicides has led to increasing difficulties in plant parasitic nematode management, in particular the newly emerged root-knot nematode (RKN) Meloidogyne minor. Infestation by this nematode results in stunted development of turf-grass and consequently the appearance of chlorosis. This damage is largely the result of the nematodes invasive endoparasitic life-cycle. Although M. minor has been found in potato crops, its appearance is steadily increasing in sports amenity sites. Initially this study investigated the population dynamics of plant parasitic nematodes (PPN) on sports amenity sites in the UK and Ireland. The investigation suggests that PPN ecology within these Isles is somewhat different to what is observed in the USA. The availability of a turf naturally resistant to key pest M. minor, was investigated leading to the suggestion that the propensity to adopt USGA specification and trends may not be appropriate for our more temperate climate which appears to be a factor in the proliferation of M. minor and other genera. The study progressed to exploring the effects of natural nematicidial compounds, such as biostimulants and plant extracts on turf development, plant resistance and PPN control. The key trend to emerge from the data was that of hyper-vari"lbility, a trend also reflected in the current available literature. However the potential for a plant based nematicide could not be ruled out; the data indicated promising in vitro effects on PPN mobility follOWing treatment with natural plant extracts, but the need for further exploration is apparent. Overall the investigations outlined in this study indicate that PPN management within sports amenities will no longer be as straightforward as applying a quick-fix nematiticide . Further study is most ardently warranted and it would be suggested that successful control of PPN within sports amenities will involve a relatively complex program incorporating observation of PPN ecology, lessening of external stress opposed to turf and careful selection and application of approved nematicidal products.
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Kempster, Valerie N. "Soil microbes as potential control agents for plant-parasitic nematodes in pasture /." Title page, contents and summary only, 2000. http://web4.library.adelaide.edu.au/theses/09ACP/09acpk32.pdf.
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Johnston, M. J. G. "The neuropeptide signalling system as a drug target in plant parasitic nematodes." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431591.
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McKinney, S. L. "The neuropeptidergic signalling system as a drug target in plant parasitic nematodes." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411746.
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Baker, Timothy John. "Interactions between arbuscular mycorrhizal fungi and plant parasitic nematodes on banana roots." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245322.
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Luc, John Eric. "Effects of plant parasitic nematodes and nitrogen fertility management on hybrid bermudagrass." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004412.
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Birtle, Alan John. "Development of controlled-release pesticide formulations for use against plant parasitic nematodes." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37642.
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Kapoor, Sharmila. "Investigation of nematode digestive enzymes and their inhibition in transgenic plants." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319137.
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Feil, John Joseph. "Factors influencing the development of fourth stage juveniles of Ditylenchus dipsaci." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305783.
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Navarro, Patricia D. "Entomopathogenic Nematodes: Their Interactions with Plant Pathogens and Insecticides in the Soil." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/265815.
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Entomopathogenic nematodes (EPNs) in the families Heterorhabditidae and Steinernematidae, and their bacterial symbionts, have been studied intensively because of their role as natural mortality factor for soil-dwelling arthropods, and their potential as biological control agents for belowground insect pests. Moreover, EPN are recognized as key players in regulating soil food webs and triggering trophic cascades. However, most studies of interactions with EPN have been conducted under laboratory setting and simplified conditions, without consider the dynamic of the EPN and their interactions with other soil components in a wider context. In this respect, knowledge of the effect that other soil organisms or human induced factor may have on EPN dynamic and life cycle in the soil may contribute to improve tactics for their implementation and success as natural regulators of herbivores. The present investigation focused on the interactions of EPN with a selection of insecticides, and biotic (saprobic fungus and plant parasitic nematodes) elements that may be present in the soil, and may potentially interact with EPN. Specifically, I investigated how these factors may affect the life cycle (host search behavior, virulence and reproduction) of EPN. Appendix A shows the effect that a group of selected synthetic and biological insecticides have on EPN virulence and reproduction. The results obtained from this study revealed that most combinations of EPN and insecticides under study increased the mortality of the insect host. However, it was also found that some of these combinations reduced the nematode progeny production and emergence of IJs from the insect cadaver. In contrast in Appendix B, when examining the effect of the saprobic fungus Fusarium oxysporum in the life cycle of the EPN Heterorhabditis sonorensis, it was found that this fungus negatively affected the virulence and reproduction of the EPN in the insect host. In the third study of this dissertation (Appendix C) the interactions studied considered the effect of two EPN on an organism of a different trophic guild, the plant parasitic nematode Tylenchulus semipenetrans. This plant parasitic nematode causes serious diseases in citrus plants by infecting their roots and defoliating their branches. Previous studies have shown that some EPN species may negatively affect the life cycle of plant parasitic nematodes by reducing the damage produced by this plant parasite. Results from this study confirm the antagonistic effect between the selected EPN and the citrus nematode. Specifically, it was found that the presence in the soil of both EPN reduced the survival of infective juveniles of the citrus nematode and their penetration to the root. Moreover, the presence of EPN had an antagonistic effect in the production of eggs of T. semipenetrans females.
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Coyne, Daniel L. "Epidemiology and crop loss assessment of rice nematodes in West Africa." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299612.
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Stevenson, Michael Andrew. "RNA interference as a tool to control plant parasitic nematode infestation in key plant crops." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677278.
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The work presented in this thesis documents studies on the impact of RNA interference (RNAi) on potential control target genes and how this alters the phenotype of the pre-parasitic stage of the plant parasitic nematodes (PPN), Globodera pallida and Meloidogyne incognita. A wide range of targets were selected across all the main tissue types within the worms (hypodermis, muscle, nervous system, subventral gland, dorsal gland) and significant knockdown was achieved (using short-interfering [si]RNAs) in all tissue types except the dorsal gland. Overall, the data strongly support the utility of PPN J2s as a model for functional genomics studies using RNAi. Further work was carried out on selected targets including the neuropeptide-encoding genes, Gp-flp-30 and Gp-flp-31 which are thought to be only expressed in PPN species. These targets showed reduced target transcript levels following RNAi, however not to the same degree as most of the previously targeted genes; their silencing did not induce a significant phenotype suggesting they are involved in functions other than normallocomotion/chemotaxis. We also targeted Gp-flp-21 and its putative receptor encoding gene Gp-flp-21 R which in Caenorhabditis elegans modulate sociality. Silencing either gene did not alter PPN motility but did disrupt positive chemotaxis, consistent with a role in chemosensation and consistent with the FLP-21 R being the FLP-21 receptor. Finally, the work reported here has shown that silencing Gp-ace-2, which encodes an acetylcholinesterase, results in complete paralysis of the parasites and prevents them from infecting their host plant and thus complete their life cycle. These data provide functional validation for a variety of PPN control targets.
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Ntidi, Keikantsemang Nancy. "Plant-parasitic nematodes associated with weeds in developing agriculture with special reference to root-knot nematodes / Keikantsemang Nancy Ntidi." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2055.
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Kimber, M. J. "Characterisation of plant parasitic nematode neuropeptides and their use as nematicidal agents." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391117.
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Bakhetia, Manjula. "Targets for plant parasitic nematode resistance using functional genomics and RNAi tools." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406880.
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Eves-van, den Akker Sebastian. "Molecular and bioinformatic analyses of nematode-derived proteins involved in plant-parasitism." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7421/.
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Plant parasitic nematodes comprise several groups; the most economically damaging of these are the sedentary endoparasites. Sedentary endoparasitic nematodes modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Ultrastructural studies of plant-nematode interactions, and in particular those of the feeding sites, have identified two key feeding structures; feeding tubes and feeding plugs. Sedentary plant-parasitic nematodes feed by withdrawing host cell assimilate from the feeding site though a feeding tube. The function, composition and molecular characteristics of both feeding tubes and feeding plugs are poorly characterised. It is hypothesised that the apparent selective uptake of certain proteins from the feeding site is attributed to feeding tube size exclusion. A novel method is proposed to predict protein size based on protein database coordinates in silico. The validity of these predictions was tested using travelling wave ion mobility spectrometry – mass spectrometry, where predictions and measured values were within approximately 6% of each other. In silico predictions coupled with experimental techniques, such as mass spectrometry, analytical ultracentrifugation and protein electrophoresis, aimed to resolve seemingly-conflicting results of previous size exclusion experiments. Together these provided a pragmatic measurement of the upper limit for cyst nematode feeding tube size exclusion. Putative feeding-structure genes were identified from the genome sequence of the potato cyst nematode Globodera pallida using a series of reasoned assumptions about their characteristics. As a result, several large gene families were identified, one of which displayed highly complex genomic variation within a population. Subsequent characterisation of these candidate genes informed their function. The expression of several candidates was demonstrated in tissues with the capacity to secrete proteins into the host, implicating their role in host-pathogen interactions. In addition, for the 444 gene family, the protein was detected in the apoplasm, between the anterior end of the nematode and the feeding site. In planta host induced gene silencing targeting 444s reduced nematode infection by > 50%; further supporting their important role in successful parasitism. Feeding structure candidate genes were identified in de novo transcriptome assemblies of two related species (Globodera rostochiensis and Rotylenchulus reniformis). Differential expression analysis identified those candidates with congruent expression between species. 444 and 448 genes appear to be “core” effectors present in three genera of plant-parasitic nematodes that infect mono- and di-cotyledonous crop species.
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Frey, Timothy S. "An Investigation of The Role of Amino Acids in Plant-Plant Parasitic Nematode Chemotaxis and Infestation." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu15659761481711.
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Vieira, Paulo. "Cell cycle maneuvering : a strategy taken by plant parasitic nematodes to induce specialized feeding sites in plant roots." Nice, 2012. http://www.theses.fr/2012NICE4114.
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De, Beer Ernst Friedrich Ludwig. "The efficacy of abamectin in reducing plant-parasitic nematodes in cotton / E.F.L. de Beer." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4398.
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Cotton production is worldwide hampered by infection of various pests and diseases, including plant-parasitic nematodes (PPN). Root-knot nematodes (RKN), in particular Meloidogyne incognita race 4 is the predominant nematode species and race that adversely affects the production of cotton in South Africa and thus result in substantial yield losses. Management strategies that are frequently used to minimize yield losses in cotton locally are limited to a few registered nematicides and to a lesser extent, crop rotation. In addition, no resistant cotton cultivars are available that are adapted to local climatic conditions. The main objective of this study was to evaluate the efficacy of abamectin against PPN, particularly M. incognita race 4, in greenhouse and field trials. The host suitability of four cultivars Delta OPAL®, Nu OPAL®, Nu OPAL RR® and Delta OPAL RR®
that were used in the greenhouse trial were concurrently also evaluated against M. incognita race 4. To conduct this study, mature RKN females that were present in roots of tomato (cv. Rodade) and produced egg masses from which eggs and J2 (used as inoculum source for the greenhouse trial) were identified using Deoxyribonucleic Acid (DNA)-based techniques. The same procedure was followed for females that were present in roots of cotton cultivars that were planted in field trials. With regard to the greenhouse trial, two treatments namely abamectin at a dosage rate of 0.15mg a.i./seed as well as a non-abamectin (untreated control) treatment were used. Approximately 2 500 M. incognita race 4 eggs and J2 were inoculated per cotton seed at planting for four cultivars (Delta OPAL ®, Nu OPAL®, Nu OPAL RR® and Delta OPAL RR®) that were used. Nematode parameters viz. numbers of eggs and J2, egg masses and galls per root system as well as egg-laying female (ELF) indices and reproduction (Rf) values were obtained during five sampling intervals. These intervals represented the major growth stages of cotton plants, namely first true leaf, square, flower and boll development as well as when 50% of the bolls were opening. In addition, root mass (g) and biomass (g) data per cotton plant were also obtained. The trial layout was a randomized complete split-plot design including the two treatments, five sampling intervals and the four cultivars, which were replicated six times. Nematode and plant growth stage data were subjected to a factorial analysis of variance (ANOVA) with treatments as factor 1, sampling intervals as factor 2 and cultivars as factor 3. Means were separated by the Tukey Test and degrees of freedom (error) > 18 were always pursued. Nematode data for nematode parameters (dependent variables) were non-linearly regressed on the various sampling intervals (independent variable) using polynomial models (Genstat for Windows), while plant data (dependent variable) were linearly regressed using the sampling intervals (the independent variable). The RKN species and race that was used as inoculum for the greenhouse trial proved to be M. incognita race 4 using the specific sequenced characterized amplified region (SCAR)-polymerase chain reaction (PCR) method. Although the 0.15mg abamectin a.s./seed treatment resulted in a significant (P ? 0.05) reduction in M. incognita race 4 population levels in roots of the four cultivars, these levels were still relatively high. Significant differences (P ? 0.05) were also evident among the sampling intervals for both the abamectin and non-abamectin treatments with regard to all nematode and plant growth parameters. Further, the four cultivars were identified as susceptible hosts to this RKN species and race and generally had similar non-linear regression lines for the non-abamectin treatment in terms of M. incognita race 4-population development during the duration of the trial. These cultivars did, however, differ significantly (P ? 0.05) from each other in terms of particularly the eggs and J2/root system only for the abamectin treatment when data were pooled for the five sampling intervals. Cultivar Nu OPAL® maintained significant (P ? 0.05) higher egg and J2 numbers/root system than those maintained by the other three cultivars. This cultivar was, however, still classified as being highly susceptible (like the other three cultivars) to M. incognita race 4 using Rf values. For the latter as well as other nematode parameters, namely egg mass and gall numbers/root system as well as ELF indices significant (P ? 0.05) differences were only evident between the two treatments and the five sampling intervals, but not for the cultivars. With regard to interaction data those that were significant (P ? 0.05) between the two treatments and five sampling intervals for all the nematode and plant parameters, were regarded as the most important. This indicated that the treatments reacted differently during these intervals for all parameters measured. Since this trial was conducted in a greenhouse under controlled conditions, nematode and plant growth data obtained should be verified in field trials throughout the cotton-producing areas of South Africa under natural occurring environmental conditions. Only then can final conclusions be made in this regard. For evaluation and verification of the efficacy of abamectin as a seed treatment in reducing PPN populations particularly M. incognita race 4, field trials were conducted at five sites where cotton was commercially grown during the 2005/2006 and 2006/2007 growing seasons. Four trials were conducted at three sites that are located in commercially-grown cotton fields in the Marble Hall area (Limpopo Province), while the other trial was done in the Vaalharts area near Jan Kempdorp (Northern Cape Province). For abamectin, two dosage treatments, namely 0.15mg a.s./seed and 0.30mg a.s./seed were used in all field trials. Standard treatments included were the classical nematicides aldicarb and fenamiphos that are registered on cotton in South Africa. An untreated control as well as a thiamethoxam 0.3mg a.s./seed treatment were also included for the 2005/2006 trials. In addition to these treatments, a seventh treatment containing abamectin 0.15mg a.s./seed + thiamethoxam 0.3mg a.s./seed was included during the 2006/2007 season. Cotton seed used to plant trials during the 2005/2006 season were those for cultivar Nu OPAL®, while Nu OPAL RR® was used during the 2006/2007 season. Trial layouts for all trials constituted a randomized complete block design with nine and six replicates during the 2005/2006 and 2006/2007 growing seasons, respectively. Both root and soil samples were taken for nematode extraction, counts and identification purposes from the outer two rows of each plot at 42 as well as 84 days after planting (DAP), except when excessive rainfall occurred. Nematode and yield data for all trials were subjected to analyses of variance (ANOVA). For yield estimation, cotton lint was also harvested for all trials, weighed and subjected to ANOVAS. Meloidogyne incognita race 4 has been identified as the predominant PPN species and race being present at all trial sites, while low population levels of individuals from the Hoplolaimidae, Criconema spp., Pratylenchus spp. and Paratrichodorus spp. were also present. The standard nematicide treatments aldicarb and fenamiphos generally resulted in the lowest number of M. incognita race 4 eggs and J2/root system in all trials and differed significantly from those for the untreated control treatments for three trials. The 0.15mg abamectin dosage treatment in particular did generally not differ significantly (P ? 0.05) from the untreated control treatments nor from the standard nematicide and the thiamethoxam 0.3mg treatment as well as for the abamectin 0.15mg a.s./seed + thiamethoxam 0.3mg treatment during sampling interval one for two of the trials and during sampling intervals one and two for the other. Yield for the abamectin 0.15mg a.s./seed treatment was significantly (P ? 0.05) higher than that of the untreated control only for Trial A. In terms of the cost-effectiveness, the estimated cost of the 0.15mg abamectin a.s./seed treatment was calculated to be substantially lower than those for the two standard nematicide treatments for the latter trial. This scenario poses a potential benefit for producers when this abamectin dosage will be used. Although the 0.15mg abamectin dosage treatment showed potential to reduce population levels of M. incognita race 4 during this study, data varied between trials and seasons for the field trials. It must, however, be emphasised that since M. incognita race 4 populations in roots of abamectin-treated cotton plants were comparable to those for the standard nematicides as well as those of the untreated controls, additional management strategies should be used in combination with the abamectin treatment. It further accentuates that abamectin should preferably be used only where population levels of M. incognita race 4 are not particularly high.<br>Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2010.
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Aalten, Patricia Mischa. "Antagonistic effects of entomopathogenic nematodes (Steinernema spp.) and fluorescent Pseudomonas rhizobacteria on the plant-parasitic nematodes Radopholus similis and Meloidogyne spp." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245334.
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