Human influence on the dispersal and genetic structure of French Globodera tabacum populations

Alenda, Charline; Montarry, Josselin; Grenier, Éric

doi:10.1016/j.meegid.2014.07.027

Cited by 27 publications

(42 citation statements)

References 37 publications

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“…; Plantard & Porte ; Alenda et al . ). This is the hypothesis that has been presented in these cases and others (Gilabert & Wasmuth ), although alternative explanations exist (see above) and have not been explored.…”

Section: Introductionmentioning

confidence: 97%

Heterozygote deficits in cyst plant‐parasitic nematodes: possible causes and consequences

et al. 2015

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Deviations of genotypic frequencies from Hardy-Weinberg equilibrium (HWE) expectations could reveal important aspects of the biology of populations. Deviations from HWE due to heterozygote deficits have been recorded for three plant-parasitic nematode species. However, it has never been determined whether the observed deficits were due (i) to the presence of null alleles, (ii) to a high level of consanguinity and/or (iii) to a Wahlund effect. The aim of the present work was, while taking into the possible confounding effect of null alleles, to disentangle consanguinity and Wahlund effect in natural populations of those three economically important cyst nematodes using microsatellite markers: Globodera pallida, G. tabacum and Heterodera schachtii, pests of potato, tobacco and sugar beet, respectively. The results show a consistent pattern of heterozygote deficiency in the three nematode species sampled at the spatial scale of the host plant. We demonstrate that the prevalence of null alleles is weak and that heterozygote deficits do not have a single origin. Our results suggested that it is restricted dispersal that leads to heterozygote deficits through both consanguinity and substructure, which effects can be linked to soil movement, cyst density, and the number of generations per year. We discuss potential implications for the durability of plant resistances that are used to protect crops against parasites in which mating between relatives occur. While consanguineous mating leads to homozygosity at all loci, including loci governing avirulence/virulence, which favours the expression of virulence when recessive, the Wahlund effect is expected to have no particular effect on the adaptation of nematodes to resistances.

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Section: Introductionmentioning

confidence: 97%

Heterozygote deficits in cyst plant‐parasitic nematodes: possible causes and consequences

et al. 2015

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“…They move only short distances and, thus their dissemination is via water [10] and wind [11]. Human activities such as the introduction of infected planting material or diffusion of infested soil with nursery practices also contribute to spreading [12]. Meloidogyne spp.…”

Section: Introductionmentioning

confidence: 99%

Diversity of root-knot nematodes in Moroccan olive nurseries and orchards: does Meloidogyne javanica disperse according to invasion processes?

et al. 2017

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BackgroundRoot-knot nematodes (RKN) are major pest of olive tree (Olea europaea ssp. europaea), especially in nurseries and high-density orchards. Soil samples were collected from main olive growing areas of Morocco, to characterize Meloidogyne species and to discuss the contribution of biotic and abiotic factors in their spatial distribution.ResultsRKN were found in 159 soil samples out of 305 from nurseries (52.1% occurrence) and in 11 out of 49 soil samples from orchards (23.2% occurrence). Biochemical and molecular characterisation (PAGE esterase and SCAR) revealed the dominance of M. javanica both in nurseries and orchards with minor presence of M. incognita only in nurseries, and M. arenaria in only one nursery. RKN were distributed on aggregated basis. Frequent presence of M. javanica in orchards might have come from nurseries. In contrast, the detection of M. incognita in nurseries alone suggests that this species could not reproduce in orchards because of either the competition with other plant-parasitic nematodes or unfit local habitats. The impact of environmental variables (climate, habitat origin and physicochemical characteristics of the substrates) on the distribution of Meloidogyne species is also discussed.ConclusionOlive nurseries in Morocco are not able to guarantee the safety of rooted plants. As a result, olive production systems are exposed to strong RKN invasion risks. Consequently, the use of healthy substrates in nurseries may prevent plant-parasitic nematode induction in orchards.

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“…Anthropogenic influence on pathogen dispersal has already been reported for several species (Lebarbenchon et al., ; Morgan et al., ), including nematodes. Patterns of population genetic structure matched those of agricultural practices within and among field populations of G. tabacum and X. index (Alenda et al., ; Villate et al., ), and potato tuber trade favors the spreading of G. pallida and G. rostochiensis worldwide (Boucher et al., ; Plantard et al., ).…”

Section: Discussionmentioning

confidence: 91%

Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 2. Separating the relative effects of gene flow and genetic drift

Gracianne

Jan

Fournet

et al. 2016

Evolutionary Applications

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Studying wild pathogen populations in natural ecosystems offers the opportunity to better understand the evolutionary dynamics of biotic diseases in crops and to enhance pest control strategies. We used simulations and genetic markers to investigate the spatial and temporal population genetic structure of wild populations of the beet cyst nematode Heterodera schachtii on a wild host plant species, the sea beet (Beta vulgaris spp. maritima), the wild ancestor of cultivated beets. Our analysis of the variation of eight microsatellite loci across four study sites showed that (i) wild H. schachtii populations displayed fine‐scaled genetic structure with no evidence of substantial levels of gene flow beyond the scale of the host plant, and comparisons with simulations indicated that (ii) genetic drift substantially affected the residual signals of isolation‐by‐distance processes, leading to departures from migration–drift equilibrium. In contrast to what can be suspected for (crop) field populations, this showed that wild cyst nematodes have very low dispersal capabilities and are strongly disconnected from each other. Our results provide some key elements for designing pest control strategies, such as decreasing passive dispersal events to limit the spread of virulence among field nematode populations.

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Human influence on the dispersal and genetic structure of French Globodera tabacum populations

Cited by 27 publications

References 37 publications

Heterozygote deficits in cyst plant‐parasitic nematodes: possible causes and consequences

Heterozygote deficits in cyst plant‐parasitic nematodes: possible causes and consequences

Diversity of root-knot nematodes in Moroccan olive nurseries and orchards: does Meloidogyne javanica disperse according to invasion processes?

Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 2. Separating the relative effects of gene flow and genetic drift

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