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Henri Darmency - One of the best experts on this subject based on the ideXlab platform.
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Effects of fragmentation and population size on the genetic diversity of Centaurea cyanus (Asteraceae) populations
Plant Ecology and Evolution, 2015Co-Authors: Cécile Petit, Helene Arnal, Henri DarmencyAbstract:Aims - Centaurea cyanus L. is a patrimonial species emblematic of the flora associated with cereal crops, but it is currently declining in Western Europe because of agricultural intensification. The decrease in both the area and connectivity of populations could affect the genetic structure and variability of the populations, and in turn their potential to survive. Methods - We studied the genetic variability of ten large and five small C. cyanus populations from two contrasted French regions using seven nuclear isozyme markers, and of twelve Western European populations using eighteen chloroplast markers. Results - The analysis of leaf isozymes revealed that all populations, except one, had a deficit of heterozygous individuals (average Fis = 0.81), which could confirm the presence of a proportion of self-compatible plants. The level of variability was high. Genetic diversity was not lower in small than in large populations, and there was no reduced genetic diversity in the region where C. cyanus populations are rare. There was low but significant differentiation among populations (Fst = 0.068), especially between small and large populations, but not between regions. In contrast, no polymorphism was found among the 371 chloroplast DNA sequences analysed (i.e. around 8-10% of the chloroplast genome). Conclusions - The observed pattern of variability could reflect the first effects of the rarefaction and fragmentation of previously abundant, widely distributed and poorly structured C. cyanus populations, on the reproduction regime and onset of genetic heterogeneity among populations.
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Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species
Flora - Morphology Distribution Functional Ecology of Plants, 2015Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Solène Touzeau, Henri DarmencyAbstract:Abstract The evolutionary trajectory of isolated or small populations of self-incompatible species depends on genetic variation in the capacity to transition to self-compatibility and the impact of inbreeding on plant fitness. Centaurea cyanus is an example of a self-incompatible, arable field-dependent weed species that is in regression in western Europe due to agricultural intensification. However, some cases of self-fertilization have been observed. Here, we investigated how inbreeding depression impacts the plants by studying two generations of self-fertilized families. As early as at the stage of the first selfing generation, we observed reduction in the number of florets per capitulum. By the second selfing generation, we observed reductions in germination rate, plant height, above-ground plant biomass, seed set and the final number and mass of seeds per plant. In particular, dramatically lower germination rate and reduced seed set contributed to a low cumulative fitness index of the generations that resulted from selfing. Nevertheless, although high average inbreeding depression was observed, large variation in cumulative fitness among families would allow some of these selfed families to persist and trigger evolution of selfing in small, isolated populations.
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Pre-dispersal seed mortality in Centaurea cyanus
2014Co-Authors: Stanislava Koprdova, Solène Bellanger, Henri DarmencyAbstract:Seed production is reduced by various kinds of pests, including those hosted by the fruit that impact seed ripening and viability indirectly, and those directly attacking the seeds before they are released. This results in pre-dispersal seed mortality, which may have strong effects on plant population dynamics. However, compensative evolution (or co-evolution) could select for fruits with adapted morphology. We wonder if pre-dispersal mortality could limit the population growth rate and contribute to the decline of Centaurea cyanus L. (also cyanus segetum, Hill). The present study focused on the occurrence and abundance of seed-feeding insects of cornflower flower heads, and their relationships to capitula size, seed viability and germination. Larger capitula had lower proportion of healthy seeds. Although no visible damage was observed to the seeds of C. cyanus, the presence of cecidomye larvae inside the capitula correlated with seed loss. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed seeds of cornflower. A higher rate of aborted seeds in presence of gall midge larvae could have resulted from fewer visits by pollinators, which may have been repelled, or from the deprivation of resources (by the larvae).The viability of the apparently healthy seeds is lower when the capitulum contains aborted seed and/or larvae. In conclusion, pre-dispersal mortality could select against the evolution of the species toward larger capitula, and have detrimental consequences on seed number, viability and germination, which limit the spread of C. cyanus populations.
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Pseudo-self-compatibility in Centaurea cyanus L
Flora, 2014Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Henri DarmencyAbstract:Agricultural intensification has resulted in drastic regression of several arable land-dependent weeds. This decrease, along with reduced pollinator abundance, could lead to population-level extinction of self-incompatible species. Alternatively, it could drive adaptation to self-compatibility through selection on standing genetic variation. We investigated whether pseudo-self-compatible (PSC) or self-compatible (SC) plants are present in populations of the rarified weed Centaurea cyanus in the species’ extreme western distribution limits in Europe. We compared seed production of isolated plants and of pairs of plants in cages with or without pollinators. We showed that pollinators are necessary for self-fertilization. The majority of plants were self-incompatible (SI), but about 12% were PSC, and one was SC. Reproductive traits of PSC plants were not different from those of other plants. There was no difference between plants from two regions that differed in C. cyanus abundance. We conclude that the genetic variation necessary to transition to selfing is present in C. cyanus; this could help to maintain endangered populations, but the transition to selfing does not appear to have happened in nature yet.
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Centaurea cyanus as a biological indicator of segetal species richness in arable fields
Weed Research, 2012Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Vincent Bretagnolle, Henri DarmencyAbstract:Bellanger S, Guillemin J-P, Bretagnolle V & Darmency H (2012). Centaurea cyanus as a biological indicator of segetal species richness in arable fields. Weed Research52, 551–563. Summary Agricultural intensification has resulted in a loss of biological diversity within European agroecosystems. Biological indicator species are important tools for monitoring species diversity. The aim of this study was to determine whether cornflower, Centaurea cyanus, an arable land specialist segetal species that is easily identified in the countryside, is an appropriate indicator of weed species diversity in the Poitou-Charentes region of western France. The study zones selected were those in which C. cyanus was present in agricultural fields when monitoring was conducted in both 2006 and 2007. All plant species in sample fields sown with winter crops (cereals and oilseed rape) within the study zones were then inventoried in two consecutive years: 2008 and 2009. For these winter crops, C. cyanus presence was not a good indicator of overall species richness within the fields. However, C. cyanus presence did correlate with the presence of other arable land specialists, herein called segetal species. Reciprocally, the presence of most other segetal species found at low frequencies in the study zones also correlated with higher segetal richness. We discuss the conditions for using C. cyanus as an indicator of segetal diversity with regards to conservation and ecosystem services.
Jean-philippe Guillemin - One of the best experts on this subject based on the ideXlab platform.
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Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species
Flora - Morphology Distribution Functional Ecology of Plants, 2015Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Solène Touzeau, Henri DarmencyAbstract:Abstract The evolutionary trajectory of isolated or small populations of self-incompatible species depends on genetic variation in the capacity to transition to self-compatibility and the impact of inbreeding on plant fitness. Centaurea cyanus is an example of a self-incompatible, arable field-dependent weed species that is in regression in western Europe due to agricultural intensification. However, some cases of self-fertilization have been observed. Here, we investigated how inbreeding depression impacts the plants by studying two generations of self-fertilized families. As early as at the stage of the first selfing generation, we observed reduction in the number of florets per capitulum. By the second selfing generation, we observed reductions in germination rate, plant height, above-ground plant biomass, seed set and the final number and mass of seeds per plant. In particular, dramatically lower germination rate and reduced seed set contributed to a low cumulative fitness index of the generations that resulted from selfing. Nevertheless, although high average inbreeding depression was observed, large variation in cumulative fitness among families would allow some of these selfed families to persist and trigger evolution of selfing in small, isolated populations.
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Pseudo-self-compatibility in Centaurea cyanus L
Flora, 2014Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Henri DarmencyAbstract:Agricultural intensification has resulted in drastic regression of several arable land-dependent weeds. This decrease, along with reduced pollinator abundance, could lead to population-level extinction of self-incompatible species. Alternatively, it could drive adaptation to self-compatibility through selection on standing genetic variation. We investigated whether pseudo-self-compatible (PSC) or self-compatible (SC) plants are present in populations of the rarified weed Centaurea cyanus in the species’ extreme western distribution limits in Europe. We compared seed production of isolated plants and of pairs of plants in cages with or without pollinators. We showed that pollinators are necessary for self-fertilization. The majority of plants were self-incompatible (SI), but about 12% were PSC, and one was SC. Reproductive traits of PSC plants were not different from those of other plants. There was no difference between plants from two regions that differed in C. cyanus abundance. We conclude that the genetic variation necessary to transition to selfing is present in C. cyanus; this could help to maintain endangered populations, but the transition to selfing does not appear to have happened in nature yet.
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Centaurea cyanus as a biological indicator of segetal species richness in arable fields
Weed Research, 2012Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Vincent Bretagnolle, Henri DarmencyAbstract:Bellanger S, Guillemin J-P, Bretagnolle V & Darmency H (2012). Centaurea cyanus as a biological indicator of segetal species richness in arable fields. Weed Research52, 551–563. Summary Agricultural intensification has resulted in a loss of biological diversity within European agroecosystems. Biological indicator species are important tools for monitoring species diversity. The aim of this study was to determine whether cornflower, Centaurea cyanus, an arable land specialist segetal species that is easily identified in the countryside, is an appropriate indicator of weed species diversity in the Poitou-Charentes region of western France. The study zones selected were those in which C. cyanus was present in agricultural fields when monitoring was conducted in both 2006 and 2007. All plant species in sample fields sown with winter crops (cereals and oilseed rape) within the study zones were then inventoried in two consecutive years: 2008 and 2009. For these winter crops, C. cyanus presence was not a good indicator of overall species richness within the fields. However, C. cyanus presence did correlate with the presence of other arable land specialists, herein called segetal species. Reciprocally, the presence of most other segetal species found at low frequencies in the study zones also correlated with higher segetal richness. We discuss the conditions for using C. cyanus as an indicator of segetal diversity with regards to conservation and ecosystem services.
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Les causes biologiques de la régression du bleuet (Centaurea cyanus L.)
2012Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Henri DarmencyAbstract:Dans les agroécosystèmes, un déclin de la diversité biologique causé par l’intensification des pratiques agricoles est actuellement observé. Parmi les espèces adventices, toutes ne répondent pas de la même façon à ces changements. Des traits biologiques spécifiques pourraient expliquer le déclin de certaines et la réussite d’autres. Ainsi, mieux comprendre les causes biologiques de la régression permettrait de mettre en place des stratégies de gestion dans ces systèmes agricoles intensifs. Le bleuet (Centaurea cyanus L.) est une messicole spécialiste de l’agroécosystème qui est actuellement en régression dans l’ouest de l’Europe . Cette espèce est par ailleurs considérée comme emblématique de la flore des champs. Dans cette étude, nous nous sommes focalisés sur les causes biologiques qui ont pu entrainer son déclin. Le système de reproduction, facteur décisif à la réussite d’une espèce, nous a plus particulièrement intéressé. La présence d’un système d’auto‐incompatibilité et l’obligation de la pollinisation par les insectes ont ainsi été montrées et pourraient représenter des caractéristiques biologiques non adaptées dans l’agroécosystème où les populations végétales sont généralement fragmentées et où les pollinisateurs sont en déclin. La présence d’individus pseudo auto‐incompatibles a été mise en évidence quelque soit la taille et/ou le niveau d’isolement des populations et pourrait permettre le maintien de certaines populations en régression dans l’ouest de l’Europe. Cependant, ce processus de sauvetage entraine un coût sur la fitness des individus via l’apparition de la dépression de consanguinité, qui, lorsqu’elle est trop importante, pourrait contribuer au déclin du bleuet. Par ailleurs, les services écosystémiques rendus par cette espèce messicole seront aussi discutés.
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Centaurea cyanus L. as a biological indicator of segetal species richness in arable fields
Weed Research, 2012Co-Authors: S. Bellanger, Jean-philippe Guillemin, Vincent Bretagnolle, H. DarmencyAbstract:Agricultural intensification has resulted in a loss of biological diversity within European agroecosystems. Biological indicator species are important tools for monitoring species diversity. The aim of this study was to determine whether cornflower, Centaurea cyanus, an arable land specialist segetal species that is easily identified in the countryside, is an appropriate indicator of weed species diversity in the Poitou-Charentes region of western France. The study zones selected were those in which C. cyanus was present in agricultural fields when monitoring was conducted in both 2006 and 2007. All plant species in sample fields sown with winter crops (cereals and oilseed rape) within the study zones were then inventoried in two consecutive years: 2008 and 2009. For these winter crops, C. cyanus presence was not a good indicator of overall species richness within the fields. However, C. cyanus presence did correlate with the presence of other arable land specialists, herein called segetal species. Reciprocally, the presence of most other segetal species found at low frequencies in the study zones also correlated with higher segetal richness. We discuss the conditions for using C. cyanus as an indicator of segetal diversity with regards to conservation and ecosystem services.
Solène Bellanger - One of the best experts on this subject based on the ideXlab platform.
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Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species
Flora - Morphology Distribution Functional Ecology of Plants, 2015Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Solène Touzeau, Henri DarmencyAbstract:Abstract The evolutionary trajectory of isolated or small populations of self-incompatible species depends on genetic variation in the capacity to transition to self-compatibility and the impact of inbreeding on plant fitness. Centaurea cyanus is an example of a self-incompatible, arable field-dependent weed species that is in regression in western Europe due to agricultural intensification. However, some cases of self-fertilization have been observed. Here, we investigated how inbreeding depression impacts the plants by studying two generations of self-fertilized families. As early as at the stage of the first selfing generation, we observed reduction in the number of florets per capitulum. By the second selfing generation, we observed reductions in germination rate, plant height, above-ground plant biomass, seed set and the final number and mass of seeds per plant. In particular, dramatically lower germination rate and reduced seed set contributed to a low cumulative fitness index of the generations that resulted from selfing. Nevertheless, although high average inbreeding depression was observed, large variation in cumulative fitness among families would allow some of these selfed families to persist and trigger evolution of selfing in small, isolated populations.
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Pre-dispersal seed mortality in Centaurea cyanus
2014Co-Authors: Stanislava Koprdova, Solène Bellanger, Henri DarmencyAbstract:Seed production is reduced by various kinds of pests, including those hosted by the fruit that impact seed ripening and viability indirectly, and those directly attacking the seeds before they are released. This results in pre-dispersal seed mortality, which may have strong effects on plant population dynamics. However, compensative evolution (or co-evolution) could select for fruits with adapted morphology. We wonder if pre-dispersal mortality could limit the population growth rate and contribute to the decline of Centaurea cyanus L. (also cyanus segetum, Hill). The present study focused on the occurrence and abundance of seed-feeding insects of cornflower flower heads, and their relationships to capitula size, seed viability and germination. Larger capitula had lower proportion of healthy seeds. Although no visible damage was observed to the seeds of C. cyanus, the presence of cecidomye larvae inside the capitula correlated with seed loss. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed seeds of cornflower. A higher rate of aborted seeds in presence of gall midge larvae could have resulted from fewer visits by pollinators, which may have been repelled, or from the deprivation of resources (by the larvae).The viability of the apparently healthy seeds is lower when the capitulum contains aborted seed and/or larvae. In conclusion, pre-dispersal mortality could select against the evolution of the species toward larger capitula, and have detrimental consequences on seed number, viability and germination, which limit the spread of C. cyanus populations.
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Pseudo-self-compatibility in Centaurea cyanus L
Flora, 2014Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Henri DarmencyAbstract:Agricultural intensification has resulted in drastic regression of several arable land-dependent weeds. This decrease, along with reduced pollinator abundance, could lead to population-level extinction of self-incompatible species. Alternatively, it could drive adaptation to self-compatibility through selection on standing genetic variation. We investigated whether pseudo-self-compatible (PSC) or self-compatible (SC) plants are present in populations of the rarified weed Centaurea cyanus in the species’ extreme western distribution limits in Europe. We compared seed production of isolated plants and of pairs of plants in cages with or without pollinators. We showed that pollinators are necessary for self-fertilization. The majority of plants were self-incompatible (SI), but about 12% were PSC, and one was SC. Reproductive traits of PSC plants were not different from those of other plants. There was no difference between plants from two regions that differed in C. cyanus abundance. We conclude that the genetic variation necessary to transition to selfing is present in C. cyanus; this could help to maintain endangered populations, but the transition to selfing does not appear to have happened in nature yet.
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Genetic diversity of the declining arable plant Centaurea cyanus: population fragmentation within an agricultural landscape is not associated with enhanced spatial genetic structure
Weed Research, 2014Co-Authors: V. Le Corre, Solène Bellanger, J‐p Guillemin, H. DarmencyAbstract:Summary Agricultural intensification has recently resulted in the decrease in frequency and abundance of arable weed species. This includes the previously widespread Centaurea cyanus, whose populations are now fragmented and infrequent in western Europe. The consequences of habitat modification and fragmentation in terms of genetic diversity of the remaining populations have not yet been addressed. We used ten microsatellite markers to assess the genetic diversity and genetic structure of populations contained in an agricultural landscape in north-eastern France. The ten microsatellites were all highly polymorphic. Centaurea cyanus appears to be a genetically variable species, with high levels of genetic diversity within each cultivated field. Genetic structure was investigated using a Bayesian method. The partitioning of the genetic variation into three clusters was not associated with sampling locations, and most individuals were admixed. These results suggest that the cornflower populations investigated may have multiple origins in the past and that genetic variation has been reshuffled by human transportation of seeds. Thus, anthropogenic dispersal associated with farming activities is probably a major factor driving the structure of genetic diversity in arable land plants. Despite low levels of genetic differentiation between populations, fine-scale spatial genetic structure was observed within populations, suggesting limited local dispersal. We conclude that in areas where C. cyanus has become rare, the recent fragmentation of populations may in the future cause a loss of genetic diversity and even extinction.
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Centaurea cyanus as a biological indicator of segetal species richness in arable fields
Weed Research, 2012Co-Authors: Solène Bellanger, Jean-philippe Guillemin, Vincent Bretagnolle, Henri DarmencyAbstract:Bellanger S, Guillemin J-P, Bretagnolle V & Darmency H (2012). Centaurea cyanus as a biological indicator of segetal species richness in arable fields. Weed Research52, 551–563. Summary Agricultural intensification has resulted in a loss of biological diversity within European agroecosystems. Biological indicator species are important tools for monitoring species diversity. The aim of this study was to determine whether cornflower, Centaurea cyanus, an arable land specialist segetal species that is easily identified in the countryside, is an appropriate indicator of weed species diversity in the Poitou-Charentes region of western France. The study zones selected were those in which C. cyanus was present in agricultural fields when monitoring was conducted in both 2006 and 2007. All plant species in sample fields sown with winter crops (cereals and oilseed rape) within the study zones were then inventoried in two consecutive years: 2008 and 2009. For these winter crops, C. cyanus presence was not a good indicator of overall species richness within the fields. However, C. cyanus presence did correlate with the presence of other arable land specialists, herein called segetal species. Reciprocally, the presence of most other segetal species found at low frequencies in the study zones also correlated with higher segetal richness. We discuss the conditions for using C. cyanus as an indicator of segetal diversity with regards to conservation and ecosystem services.
Ikuo Ino - One of the best experts on this subject based on the ideXlab platform.
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Succinyl-coenzyme A: Anthocyanidin 3-glucoside succinyltransferase in flowers of Centaurea cyanus
Phytochemistry, 1995Co-Authors: Masa-atu Yamaguchi, Tatsunori Maki, Takako Ohishi, Ikuo InoAbstract:Abstract The acyltransferase from blue flowers of Centaurea cyanus containing succinylated cyanidin 3,5-diglucosides catalysed the transfer of the succinyl moiety from succinyl-CoA to 3-glucosides of cyanidin and pelargonidin, but not to 3,5-diglucosides. Similar results were obtained using the enzyme from pink flowers containing succinylated pelargonidin 3,5-diglucosides. The enzyme also catalysed these anthocyanidin 3-glucosides to malonylate at nearly the same rate as succinylation.
Christian Damgaard - One of the best experts on this subject based on the ideXlab platform.
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Effects of Sublethal Doses of Herbicides on the Competitive Interactions Between 2 Nontarget Plants, Centaurea cyanus L. and Silene noctiflora L
Environmental toxicology and chemistry, 2019Co-Authors: Céline Boutin, Kaitlyn Montroy, Solvejg K. Mathiassen, David Carpenter, Beate Strandberg, Christian DamgaardAbstract:Plant competitive interactions influence the effect of herbicides, and the effect of competitive interactions on plant responses may be important to include in the ecological risk assessment of herbicides. In the present study the effect of competitive interactions and sublethal doses of 2 herbicides on plant species was investigated in competition experiments and fitted to empirical competition models. Two nontarget species commonly found in agroecosystems (Centaurea cyanus L. and Silene noctiflora L.) and 2 herbicides (glyphosate and metsulfuron methyl) were used in separate experiments. Plants were sprayed at the 6- to 8-leaf stage. Effects of herbicide treatments and plant density were modeled by generalization of a discrete hyperbolic competition model. The 10% effective dose (ED10) was calculated for C. cyanus. All experiments showed that as density increased, plants were negatively affected. Furthermore, in all cases, C. cyanus remained a better competitor than S. noctiflora. Nevertheless, the density of S. noctiflora (competitor) was an influential element in determining the ED10 of C. cyanus measured at the mature stage. With herbicide exposure, the competitive interactions were further altered; C. cyanus was less affected by glyphosate when S. noctiflora increased to high density. In contrast, at the young stage, conspecific density was important in determining the sensitivity of C. cyanus to metsulfuron methyl, whereas the density of the competitor S. noctiflora had a limited influence. Overall, the results demonstrate the importance of integrating the effect of herbicide and species interactions measured at the reproductive stage into the ecological risk assessments of pesticides. Environ Toxicol Chem 2019;38:2053-2064. © 2019 SETAC.