Showing papers on "Globodera rostochiensis published in 1997"
TL;DR: The ability of strain F113 to produce DAPG was responsible for the increase in hatch ability and the reduction in juvenile mobility of G. rostochiensis, and P. fluorescens F113 is proposed as a potential biocontrol inoculant for the protection of potato crops against the potato cyst nematode.
Abstract: The potato cyst nematode Globodera rostochiensis is an important pest of potato (Solanum tuberosum). Pseudomonas fluorescens F113, which produces 2,4-diacetylphloroglucinol (DAPG), was investigated as a potential biocontrol agent against G. rostochiensis. Exposure of nematode cysts to the pseudomonad, under in vitro conditions or in soil microcosms, almost doubled the ability of the eggs to hatch. The percentage of mobile juveniles was reduced threefold following their incubation in the presence of the pseudomonad, both in vitro and in soil. Results obtained with a transposon-induced DAPG-negative biosynthetic mutant of F113 and its complemented derivative with restored DAPG synthesis showed that the ability of strain F113 to produce DAPG was responsible for the increase in hatch ability and the reduction in juvenile mobility. Similar effects on egg hatch ability and juvenile mobility of G. rostochiensis were obtained in vitro by incubating nematode cysts and juveniles, respectively, in the presence of synthetic DAPG. DAPG-producing P. fluorescens F113 is proposed as a potential biocontrol inoculant for the protection of potato crops against the potato cyst nematode.
187 citations
TL;DR: Molecular examination of the ribosomal internal transcribed spacer (ITS) region in potato cyst nematodes (PCN) is described and Polymerase chain reaction (PCR) primers based upon the G. rostochiensis–G.
Abstract: Molecular examination of the ribosomal internal transcribed spacer (ITS) region in potato cyst nematodes (PCN) is described. The ITS was amplified and sequenced from a number of PCN collections. A low level of sequence variation was found between Globodera rostochiensis, G. pallida, and a Peruvian PCN collection, but no variation within Australasian collections of species was noted. Polymerase chain reaction (PCR) primers based upon the G. rostochiensis–G. pallida sequence differences were designed and successfully used to identify mixed PCN species in a single PCR reaction.
106 citations
TL;DR: The inhibition of egg hatch of G. rostochiensis by chitinase-producing bacteria is suggested as a biocontrol strategy for the defence of potato crops from potato cyst nematodes.
Abstract: Plant-parasitic nematodes are major agronomic pests. Purified commercial chitinase inhibited egg hatch of the potato cyst nematode, Globodera rostochiensis (Ro1) in vitro by up to 70% when compared with an untreated control. A screening strategy was devised to isolate chitinase-producing bacteria from a soil with no documented history of damage due to potato cyst nematodes in the last 30 years and that was cropped with potato cv. ‘Kerr's Pink’. Only 137 of 3,200 bacterial isolates tested for chitinase production on chitin agar plates were chitinase-positive (i.e. about 4%). All the chitinase-producing bacteria tested in vitro could reduce the hatch of G. rostochiensis eggs, some by up to 90% compared with the controls. One of these strains, M1-12, was identified as Stenotrophomonas maltophilia and a second strain UP1 was classified as a Chromobacterium sp. based on morphological and biochemical tests. The inoculum level and the incubation time influenced the degree of inhibition of egg hatch of G. rostochiensis by M1-12 and UP1 in vitro. An initial cell density of 106 CFU ml-1 or greater and an incubation time of two weeks was needed to inhibit egg hatch. The longer UP1 was allowed to act on the eggs of G. rostochiensis the greater the level of inhibition. Strains M1-12 and UP1 also reduced the ability of G. rostochiensis to hatch in soil microcosms planted with potato seed tubers cv. ‘D'sir'e’. The inhibition of egg hatch of G. rostochiensis by chitinase-producing bacteria is suggested as a biocontrol strategy for the defence of potato crops from potato cyst nematodes.
83 citations
TL;DR: All the Pa2-Pa3 populations, except one from Scotland (Luffness), constituted a single group with no clear distinction based on pathotypes Pa2 and Pa3, according to random amplified polymorphic DNA (RAPD).
Abstract: Genetic variation between populations of Globodera pallida, primarily from Britain but including populations from continental Europe and South America and two Globodera rostochiensis populations, w...
43 citations
17 citations
TL;DR: It is found that few changes in gene expression appear to be induced directly by root diffusates of PCN, and changes in Gene expression seem to occur during or immediately after the hatching process.
Abstract: The potato cyst nematode (PCN) Globodera rostochiensis, like other parasitic nematodes, needs to synchronize its life-cycle with that of its host. This synchrony is achieved by the invasive-stage juvenile remaining dormant within its egg until stimulated to hatch by the presence of root diffusates of its host. Root diffusates may induce changes in gene expression in PCN, some of which may be important in the transition to a parasitic mode of existence. We have used a range of techniques including differential display to examine gene expression during stimulation and hatching of PCN. We find that few changes in gene expression appear to be induced directly by root diffusates. Instead, changes in gene expression seem to occur during or immediately after the hatching process. These results are discussed in the context of the host parasite relationship.
13 citations
TL;DR: The sex pheromone of G. rostochiensis appears to be composed of several weakly basic, polar compounds.
Abstract: Electrophysiological techniques and behavioural assays were used to determine the response of males of Globodera rostochiensis to 4 fractions of the homospecific sex pheromone from virgin females, separated using reverse-phase high-pressure liquid chromatography. Sex pheromone activity was confined to 2 of the fractions. The sex pheromone of G. rostochiensis appears to be composed of several weakly basic, polar compounds.
12 citations
TL;DR: Indirect immunofluorescence studies with LW1 indicated that at least some of the secretions were surface localized and that antibody binding to the nematode surface was periodate sensitive, and localization studies using immunoelectron microscopy demonstrated that antibodybinding could be seen to secretions found in the pump chamber of the metacorpal bulb at the base of the stylet.
Abstract: Electrophoresis of secretions collected from Globodera pallida revealed a smeared region between 25 and 50 kDa, and a single band of <20 kDa. The secretions were used to raise an antiserum (LW1). Immunoblotting of parasite homogenates with LW1 differentiated G. pallida from its sibling species G. rostochiensis and revealed differences between different populations of G. pallida and G. rostochiensis . Indirect immunofluorescence studies with LW1 indicated that at least some of the secretions were surface localized and that antibody binding to the nematode surface was periodate sensitive. Periodate sensitivity indicated that these differences could be due to glycosylation differences. Glycosylation differences were also detected by blotting nematode homogenates with the lectin wheat germ agglutinin (WGA). WGA was also able to differentiate between G. rostochiensis which gave 2 bands at 130 kDa and 110 kDa, and G. pallida which produced 2 bands present at 120 kDa and 110 kDa. Further localization studies using immunoelectron microscopy demonstrated that antibody binding could be seen to secretions found in the pump chamber
of the metacorpal bulb at the base of the stylet. From further specimens it could be observed that the contents of the subventral glands were heavily labelled, indicating that the material seen in the metacorpal bulb had originated from the subventral glands.
10 citations
TL;DR: Electrophysiological techniques and behavioral bioassays were used to evaluate the responses of males of the potato cyst nematodesGlobodera rostochiensis and G. pallidato various chemicals, finding that males of both species responded significantly in both electrophysiology and behavioral assays to L-glutamic acid but not to D-glUTamic acid.
Abstract: Electrophysiological techniques and behavioral bioassays were used to evaluate the responses of males of the potato cyst nematodesGlobodera rostochiensis and G. pallidato various chemicals. Exposure of all males of both species to acetylcholine elicited strong electrophysiological responses and positive movement towards the source. By contrast, neither glycine nor citric acid induced any marked electrophysiological responses and only males of G. pallida showed significant behavioral responses, moving toward glycine and away from citric acid. The electrophysiological and behavioral responses to GABA and α-aminobutyric acid were complementary, with G. rostochiensis showing significant response only to the latter and G. pallida responding significantly only to the former. The electrophysiological response of individuals of both species to L- and D-tryptophan varied from no response to a strong response with a significant mean increase in spike activity of G. rostochiensis to D-tryptophan and of G. pallida to L-tryptophan; behavioral bioassays showed L-tryptophan was a deterrent for G. pallida. Males of both species responded significantly in both electrophysiological and behavioral assays to L-glutamic acid but not to D-glutamic acid.
10 citations
TL;DR: A wide range of sesquiterpene levels and ratios of solavetivone to total sesQUiterpenes was recovered among the progeny, indicating that these are complex traits.
Abstract: High ratios of solavetivone to total sesquiterpenes were previously associated with derivation from a Bolivian accession of potato (Solanum tuberosum ssp. andigena CPC1673) that also confers the H1 gene for resistance to Globodera rostochiensis (golden nematode). To test the relationship between solavetivone production and nematode resistance, the inheritance of these traits was determined using four crosses among potato clones that are nematode-susceptible homozygotes or nematode-resistant heterozygotes. Progeny from each cross were screened for tuber sesquiterpene production after treatment with arachidonic acid and for nematode resistance by counting individual cysts on roots of plants inoculated in the greenhouse. Nematode resistance exhibited dominant, single-gene segregation. A wide range of sesquiterpene levels and ratios of solavetivone to total sesquiterpenes was recovered among the progeny, indicating that these are complex traits. There was no correlation between sesquiterpene levels and nemato...
9 citations
TL;DR: The ability of the cyst nematodes to respond to new types of resistance with new pathotypes makes the search and breeding for resistance a continuing process and showed that resistance, if it is to be of use in severely infested fields, must be combined with an appreciable level of tolerance.
Abstract: A description of the biology of potato cyst nematodes,Globodera rostochiensis andG. pallida, and symptom development in potato crops is presented. This is followed by an overview of resistance and tolerance research and an explanation of how resistance derived fromSolanum andigena was deployed in integrated control schemes on sandy and sandy peat soils in the north-east of The Netherlands. The frequent use of this resistance source resulted in the predominance of ‘new’ pathotypes ofG. rostochiensis and ofG. pallida. The ability of the cyst nematodes to respond to new types of resistance with new pathotypes makes the search and breeding for resistance a continuing process. The absence of tolerance in exS. vernei (VTn)2 62-33-3 cultivars showed that resistance, if it is to be of use in severely infested fields, must be combined with an appreciable level of tolerance.
Journal Article•
TL;DR: Le nombre de juveniles emergeant des kystes conserves a - 80 °C n'a pas change au cours de la periode de 4 annees.
Abstract: Des lots de kystes d'une population de Globodera rostochiensis et d'une population de G. pallida ont ete conserves a - 80 °C. Des echantillons de 50 kystes ont ete preleves regulierement et la capacite des oeufs a eclore a ete testee a 20 °C. La conservation pendant 4 ans a 4°C a reduit considerablement la capacite des oeufs a eclore dans les deux populations. Par contre, le nombre de juveniles emergeant des kystes conserves a - 80 °C n'a pas change au cours de la periode de 4 annees.
TL;DR: A simple greenhouse test, assessing root growth response to potato cyst nematode infection, provided a good insight into a cultivar's tolerance performance in the field early in the growing season.
Abstract: Greenhouse experiments on the effects of white potato cyst nematode infestations (Globodera pallida Stone) on initial growth and development of a series of potato cultivars are compared with the results of field experiments on sandy and sandy-peat soils on the effect of nematode density on tuber yield. A simple greenhouse test, assessing root growth response to potato cyst nematode infection, provided a good insight into a cultivar's tolerance performance in the field early in the growing season. As a very limited number of plants is needed for the greenhouse test, screening for tolerance can be conducted in the early stages of a breeding programme.
TL;DR: Cluster and principal coordinate analysis allowed us to hypothesise about the epidemiology of these populations and it is possible that the Luffness population was distinct from all others suggesting that it may represent a distinct introduction of PCN into the British Isles.
Abstract: Four random probes from a Globodera pallida DNA library and one rDNA repeat probe from flax were used to highlight specific fragments in total DNA restricted with the endonucleases Bam HI, Eco RI, Eco RV, and Hind III, from 26 potato cyst nematode (PCN) populations (G. rostochiensis and G. pallida). The percentage similarity between species was low (%sm = 45.6). Cluster and principal coordinate analysis allowed us to hypothesise about the epidemiology of these populations. In the G. rostochiensis group, the populations representing pathotypes Ro2, Ro3, Ro4 and Ro5 may have been derived from the same introduction. Canarian populations R1, R2, R6, R7, and R10 were distinct from all the controls but R4 and R5 were close to the British Ro1 population. In the G. pallida group, the Luffness population was distinct from all others suggesting that it may represent a distinct introduction of PCN into the British Isles. Canarian population P9 had ten markers which were absent from the European control populations and it is possible that this population represents a distinct introduction of G. pallida into the Island of Tenerife.