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Jens Kvist Nielsen - One of the best experts on this subject based on the ideXlab platform.

  • Polymorphism in a ¯ea beetle for the ability to use an atypical host plant
    2016
    Co-Authors: Peter W. De Jong, Jens Kvist Nielsen
    Abstract:

    ability to use Barbarea vulgaris R. Br. (Brassicaceae) as a host plant. The genetic factors in£uencing this ability show both sex-linked and autosomal inheritance. Evidence was found for the presence of major genes such as those found in earlier studies, but also of genes with a smaller e¡ect which have not previously been found. Although the ability to survive on B. vulgaris exists in most populations in eastern Denmark, it is usually at a low frequency. Beetles collected on B. vulgaris, however, usually produced larvae that survived on this plant. The inheritance and the abundance of the ability to use B. vulgaris are discussed in the context of the evolution of the interaction between P. nemorum and its atypical host plant

  • udp glycosyltransferases from the ugt73c subfamily in Barbarea vulgaris catalyze sapogenin 3 o glucosylation in saponin mediated insect resistance
    Plant Physiology, 2012
    Co-Authors: Jorg M Augustin, Sylvia Drok, Kazutsuka Sanmiya, Bekzod Khakimov, Esben Halkjaer Hansen, Jens Kvist Nielsen, Tetsuro Shinoda, Carl Erik Olsen, Vera Kuzina, Claus Thorn Ekstrom
    Abstract:

    Triterpenoid saponins are bioactive metabolites that have evolved recurrently in plants, presumably for defense. Their biosynthesis is poorly understood, as is the relationship between bioactivity and structure. Barbarea vulgaris is the only crucifer known to produce saponins. Hederagenin and oleanolic acid cellobioside make some B. vulgaris plants resistant to important insect pests, while other, susceptible plants produce different saponins. Resistance could be caused by glucosylation of the sapogenins. We identified four family 1 glycosyltransferases (UGTs) that catalyze 3-O-glucosylation of the sapogenins oleanolic acid and hederagenin. Among these, UGT73C10 and UGT73C11 show highest activity, substrate specificity and regiospecificity, and are under positive selection, while UGT73C12 and UGT73C13 show lower substrate specificity and regiospecificity and are under purifying selection. The expression of UGT73C10 and UGT73C11 in different B. vulgaris organs correlates with saponin abundance. Monoglucosylated hederagenin and oleanolic acid were produced in vitro and tested for effects on P. nemorum. 3-O-β-d-Glc hederagenin strongly deterred feeding, while 3-O-β-d-Glc oleanolic acid only had a minor effect, showing that hydroxylation of C23 is important for resistance to this herbivore. The closest homolog in Arabidopsis thaliana, UGT73C5, only showed weak activity toward sapogenins. This indicates that UGT73C10 and UGT73C11 have neofunctionalized to specifically glucosylate sapogenins at the C3 position and demonstrates that C3 monoglucosylation activates resistance. As the UGTs from both the resistant and susceptible types of B. vulgaris glucosylate sapogenins and are not located in the known quantitative trait loci for resistance, the difference between the susceptible and resistant plant types is determined at an earlier stage in saponin biosynthesis.

  • Genetic diversity and similarity in the Barbarea vulgaris complex (Brassicaceae)
    Nordic Journal of Botany, 2012
    Co-Authors: Fiorello Toneatto, Thure P. Hauser, Jens Kvist Nielsen, Marian Ørgaard
    Abstract:

    Two subspecies of Barbarea vulgaris are taxonomically recognized as ssp. vulgaris and ssp. arcuata. In addition, two types of Barbarea vulgaris ssp. arcuata occurs in Denmark. The G-type is resistant to an herbivorous flea beetle (Phyllotreta nemorum) whereas the P-type is susceptible. A previous study suggested that the P-type evolved by a loss of resistance from a resistant progenitor. We analyzed the genetic relatedness among eight Barbarea taxa: B. vulgaris spp. vulgaris, B. vulgaris ssp. arcuata G- and P-types, hybrids between the types, B. verna, B. intermedia, B. stricta, B. orthoceras and B. australis, using AFLP and SSR markers. A clear distinction between the G- and P-types was revealed. Both were distinct from B. vulgaris ssp. vulgaris, the G-type less so than the P-type. Barbarea verna and B. intermedia formed unambiguous clusters, whereas the remaining taxa produced less discrete groupings. Possible evolutionary scenarios for flea-beetle resistance and susceptibility are discussed, including lineage sorting from a polymorphic ancestral population, and de novo loss of resistance in the P-type of B. vulgaris ssp. arcuata.

  • Genetic and geographic structure of an insect resistant and a susceptible type of Barbarea vulgaris in western Europe
    Evolutionary Ecology, 2011
    Co-Authors: Thure P. Hauser, Fiorello Toneatto, Jens Kvist Nielsen
    Abstract:

    Interactions between herbivores and plants are believed to have been important drivers of biodiversity. However, to drive an initial resistance divergence into different evolutionary lineages and taxa, these interactions have probably been embedded in other processes of divergence, like allopatric isolation. The cruciferous plant Barbarea vulgaris ssp. arcuata occurs in Denmark in two types: one (G) is resistant to most genotypes of the flea beetle Phyllotreta nemorum, the other (P) is susceptible. The two types additionally differ in hairiness and glucosinolates, they are genetically strongly divergent, and reproduction between them is reduced. To determine whether the two plant types and their resistance polymorphisms are also present outside Denmark, and to understand how they have evolved, we analysed 33 European populations of B. vulgaris for resistance, hairiness, glucosinolates, and microsatellite markers. Most populations had traits indicative of the G type, including the already characterized Danish G populations. In contrast, only two populations outside Denmark were of the P type; one from northern Sweden and one from Estonia. Genetically, the G populations formed two genetic clusters that were strongly divergent from a genetic cluster containing P populations. A fourth genetic cluster, which contained only a single population and no Danish plants, belonged morphologically to the subspecies ssp. vulgaris. The divergence found in Denmark between a resistant G and a susceptible P type is thus part of a larger divergence in Europe. Judging from the trait correlations, genetic divergence, and partial reproductive incompatibility, the plant types must have been isolated from each other for quite some time. The two P populations outside Denmark came from the north and east, suggesting a more eastern distribution. If so, resistant and susceptible types could have diverged during the ice age and later met in Scandinavia. However, more samples from Eastern Europe are needed to clarify this.

  • Polymorphism for novel tetraglycosylated flavonols in an Eco-model crucifer, Barbarea vulgaris.
    Journal of agricultural and food chemistry, 2011
    Co-Authors: Lea Dalby-brown, Carl Erik Olsen, Jens Kvist Nielsen, Niels Agerbirk
    Abstract:

    Nineteen apparent flavonoids were determined by HPLC-DAD in foliage of a chemotype (G-type) of Barbarea vulgaris, and four were isolated. Two were novel tetraglycosylated flavonols with identical glycosylation patterns, kaempferol 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (1) and quercetin 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (2). The identification of d/l configuration was tentatively based on susceptibility to α-l-rhamnosidase and β-d-glucosidases. A characteristic feature of 1 and 2 was appreciable water solubility, an expected consequence of the extensive glycosylation. A less complex pair of flavonols comprised 3-O-β-d-glucopyranoside-7-O-α-l-rhamnopyranosides of kaempferol and quercetin. Two natural chemotypes of B. vulgaris differed in levels of 1 and 2, with the P-type deficient in 1 and 2 and the insect-resistant G-type rich in 1 (ca. 3–4 μmol/g dry wt) and with moderate levels of 2 (ca. 0.3–0.8 μmol/g dry wt). However...

Niels Agerbirk - One of the best experts on this subject based on the ideXlab platform.

  • engineering and optimization of the 2 phenylethylglucosinolate production in nicotiana benthamiana by combining biosynthetic genes from Barbarea vulgaris and arabidopsis thaliana
    Plant Journal, 2021
    Co-Authors: Cuiwei Wang, Niels Agerbirk, Christoph Crocoll, Barbara Ann Halkier
    Abstract:

    2-Phenylethylglucosinolate (2PE) derived from homophenylalanine is present in plants of the Brassicales order as a defense compound. It is associated with multiple biological properties, including deterrent effects on pests and anti-microbial and health-promoting functions, due to its hydrolysis product 2-phenylethyl isothiocyanate, which confers 2PE potential application in agriculture and industry. In this study, we characterized the putative key genes for 2PE biosynthesis from Barbarea vulgaris W.T. Aiton and demonstrated the feasibility of engineering 2PE production in Nicotiana benthamiana Domin. We used different combinations of genes from B. vulgaris and Arabidopsis thaliana (L.) Heynh. to demonstrate that: (1) BvBCAT4 performed more efficiently than AtBCAT4 in biosynthesis of both homophenylalanine and dihomomethionine; (2) MAM1 enzymes were critical for the chain-elongated profile, while CYP79F enzymes accepted both chain-elongated methionine and homophenylalanine; (3) the aliphatic but not aromatic core structure pathway catalyzed the 2PE biosynthesis; (4) a chimeric pathway containing BvBCAT4, BvMAM1, AtIPMI and AtIPMDH1 resulted in a 2-fold increase in 2PE production compared to the B. vulgaris-specific chain elongation pathway; and (5) profiles of chain-elongated products and glucosinolates partially mirrored the profiles in the gene donor plant, but were wider in N. benthamiana than in the native plants. Our study provides a strategy to produce the important homophenylalanine and 2PE in a heterologous host. Furthermore, chimeric engineering of the complex 2PE biosynthetic pathway enabled detailed understanding of catalytic properties of individual enzymes - a prerequisite for understanding biochemical evolution. The new-to-nature gene combinations have potential for application in biotechnological and plant breeding.

  • engineering and optimization of the 2 phenylethylglucosinolate production in nicotiana benthamiana by combining biosynthetic genes from Barbarea vulgaris and arabidopsis thaliana
    bioRxiv, 2020
    Co-Authors: Cuiwei Wang, Niels Agerbirk, Christoph Crocoll, Barbara Ann Halkier
    Abstract:

    Among the glucosinolate (GLS) defense compounds characteristic of the Brassicales order, several have been shown to promote human health. This includes 2-phenylethylglucosinolate (2PE) derived from homophenylalanine (HPhe). In this study, we used transient expression in Nicotiana benthamiana to validate and characterize previously predicted key genes in the 2PE biosynthetic pathway from Barbarea vulgaris and demonstrate the feasibility of engineering 2PE production. We used genes from B. vulgaris and Arabidopsis thaliana, in which the biosynthesis of GLSs is predominantly derived from HPhe and dihomomethionine, respectively. The resulting GLS profiles partially mirrored GLS profiles in the gene donor plant, but in both cases the profiles in N. benthamiana were wider than in the native plants. We found that BvBCAT4 is a more efficient entry enzyme for biosynthesis of both HPhe and dihomomethionine and that MAM1 enzymes determine the chain-elongated profile. Co-expression of the chain elongation pathway and CYP79F6 from B. vulgaris with the remaining aliphatic GLS core pathway genes from A. thaliana, demonstrated the feasibility of engineering production of 2PE in N. benthamiana. Noticeably, the HPhe-converting enzyme BvCYP79F6 in the core GLS pathway belongs to the CYP79F subfamily, a family believed to have substrate specificity towards chain-elongated methionine derivatives. Replacing the B. vulgaris chain elongation pathway with a chimeric pathway consisting of BvBCAT4, BvMAM1, AtIPMI and AtIPMDH1 resulted in an additional 2-fold increase in 2PE production, demonstrating that chimeric pathway with genes from different species can increase flux and boost production in an engineered pathway. Our study provides a novel approach to produce the important HPhe and 2PE in a heterologous host. Chimeric engineering of a complex biosynthetic pathway enabled detailed understanding of catalytic properties of individual enzymes - a prerequisite for understanding biochemical evolution - and with biotechnological and plant breeding potentials of new-to-nature gene combinations.

  • A high-density genetic map and QTL mapping of leaf traits and glucosinolates in Barbarea vulgaris.
    BMC genomics, 2019
    Co-Authors: Tong-jin Liu, Niels Agerbirk, You-jun Zhang, Hai-ping Wang, Xiao-chun Wei, Jiang-ping Song, Xue-zhi Zhao, Xiao-hui Zhang
    Abstract:

    Barbarea vulgaris is a wild cruciferous plant and include two distinct types: the G- and P-types named after their glabrous and pubescent leaves, respectively. The types differ significantly in resistance to a range of insects and diseases as well as glucosinolates and other chemical defenses. A high-density linkage map was needed for further progress to be made in the molecular research of this plant. We performed restriction site-associated DNA sequencing (RAD-Seq) on an F2 population generated from G- and P-type B. vulgaris. A total of 1545 SNP markers were mapped and ordered in eight linkage groups, which represents the highest density linkage map to date for the crucifer tribe Cardamineae. A total of 722 previously published genome contigs (50.2 Mb, 30% of the total length) can be anchored to this high density genetic map, an improvement compared to a previously published map (431 anchored contigs, 38.7 Mb, 23% of the assembly genome). Most of these (572 contigs, 31.2 Mb) were newly anchored to the map, representing a significant improvement. On the basis of the present high-density genetic map, 37 QTL were detected for eleven traits, each QTL explaining 2.9–71.3% of the phenotype variation. QTL of glucosinolates, leaf size and color traits were in most cases overlapping, possibly implying a functional connection. This high-density linkage map and the QTL obtained in this study will be useful for further understanding of the genetic of the B. vulgaris and molecular basis of these traits, many of which are shared in the related crop watercress.

  • Different herbivore responses to two co-occurring chemotypes of the wild crucifer Barbarea vulgaris
    Arthropod-Plant Interactions, 2019
    Co-Authors: Stina Christensen, Christine Heimes, Niels Agerbirk, Lp Kiaer, Swantje Enge, Karen Rysbjerg Jensen, Caroline Müller, Thure P. Hauser
    Abstract:

    According to coevolution theory, plant chemical defences are continually evolving in response to selection by herbivores. Unique to the Brassicales, a few species in the Barbarea genus produce triterpenoid saponins that are highly deterrent to some specialist insect herbivores. One species, B. vulgaris , has diverged into two chemotypes, the G- and P-type, of which the P-type seems to have lost the saponin-based insect resistance by producing different saponin structures; it also produces different glucosinolates and other potential defence traits. Here, we examined the preference and performance of a larger set of specialist and generalist herbivores on the two plant types, including three generalist mollusc ( Arion vulgaris, Deroceras sp., Cepaea sp.) as well as three specialist ( Phaedon cochleariae, Athalia rosae, Pieris napi oleraceae ) and two generalist ( Mamestra brassicae, Myzus persicae ) insect herbivores. Five out of six herbivore species preferred leaves of the P-type for feeding, and most of them also survived and/or grew better on the P-type, or preferred it for oviposition. In contrast, larvae of M. brassicae showed no preference and performed equally well on the two plant types; the leaf beetle P. cochleariae preferred the G-type for oviposition, which was, however, not reflecting larval performance. Overall, the defences of the P-type against herbivores seem not to be as effective as those of the G-type, which is surprising given its large geographical distribution, overlapping with that of the G-type in Scandinavia and Finland. This suggests that additional ecological interactions determine the success of the two chemotypes.

  • Additional file 2: of A high-density genetic map and QTL mapping of leaf traits and glucosinolates in Barbarea vulgaris
    2019
    Co-Authors: Tong-jin Liu, Niels Agerbirk, You-jun Zhang, Hai-ping Wang, Xiao-chun Wei, Jiang-ping Song, Xue-zhi Zhao, Xiao-hui Zhang
    Abstract:

    Table S1. Anchoring of sequenced contigs of G-type Barbarea vulgaris to the eight linkage groups. Table S2. Comparison of anchored contig information between this and the best previous Barbarea vulgaris genome assembly. Table S3. The trichome density, color, maximum leaf length and width, and glucosinolate content in the leaves of each individual of the F2 population of Barbarea vulgaris (ZIP 1442 kb

Carl Erik Olsen - One of the best experts on this subject based on the ideXlab platform.

  • glucosinolate hydrolysis products in the crucifer Barbarea vulgaris include a thiazolidine 2 one from a specific phenolic isomer as well as oxazolidine 2 thiones
    Phytochemistry, 2015
    Co-Authors: Niels Agerbirk, Carl Erik Olsen
    Abstract:

    Abstract Two isomeric phenolic glucosinolates, m - and p- hydroxyl derivatives of epiglucobarbarin [( R )-2-hydroxy-2-phenylethylglucosinolate], co-occur in an eastern chemotype (P-type) of the crucifer Barbarea vulgaris along with epiglucobarbarin itself. Levels of the phenolic derivatives in B. vulgaris were low in summer but higher during fall and winter, allowing isolation of all three glucosinolates. Hydrolysis in vitro , catalyzed by Sinapis alba myrosinase at near neutral pH, resulted in expectable oxazolidine-2-thione type hydrolysis products of epiglucobarbarin and its m -hydroxyl derivative. In contrast, a thiazolidine-2-one type product was formed in vitro from p -hydroxy epiglucobarbarin and characterized by UV, IR, MS/MS and 2D NMR. Maceration of leaf material resulted in disappearance of the glucosinolates and formation of the same oxazolidine-2-thione and thiazolidine-2-one products as found in vitro . The detected amounts were comparable to initial amounts of precursor glucosinolates. The corresponding oxazolidine-2-thione type product was also detected quantitatively from glucobarbarin in foliage of a western genotype (G-type). We suggest that p -hydroxy epiglucobarbarin is initially converted into the conventional oxazolidine-2-thione, which would further rearrange to a thiazolidine-2-one due to the activating effect of the p -hydroxyl group. We conclude that a subtle difference between isomeric phenolic glucosinolates results in significantly different natural hydrolysis products.

  • Multiple hydroxyphenethyl glucosinolate isomers and their tandem mass spectrometric distinction in a geographically structured polymorphism in the crucifer Barbarea vulgaris.
    Phytochemistry, 2014
    Co-Authors: Niels Agerbirk, Christine Heimes, Carl Erik Olsen, Stina Christensen, Søren Bak, Thure P. Hauser
    Abstract:

    Abstract Two distinct glucosinolate (GSL) chemotypes (P and G-types) of Barbarea vulgaris (Brassicaceae) were known from southern Scandinavia, but whether the types were consistent in a wider geographic area was not known. Populations (26) from Eastern and Central Europe were analyzed for GSLs in order to investigate whether the two types were consistent in this area. Most (21) could be attributed to one of the previously described GSL profile types, the P-type (13 populations) and the G-type (8 populations), based on differences in the stereochemistry of 2-hydroxylation, presence or absence of phenolic glucobarbarin derivatives, and qualitative differences in indole GSL decoration (tested for a subset of 8 + 6 populations only). The distinction agreed with previous molecular genetic analysis of the same individuals. Geographically, the P-type typically occurred in Eastern Europe while the G-type mainly occurred in Central Europe. Of the remaining five populations, minor deviations were observed in some individuals from two populations genetically assigned to the G-type, and a hybrid population from Finland contained an additional dihydroxyphenethyl GSL isomer attributed to a combinatorial effect of P-type and G-type genes. Major exceptions to the typical GSL profiles were observed in two populations: (1) A G-type population from Slovenia deviated by a high frequency of a known variant in glucobarbarin biosynthesis (‘NAS form’) co-occurring with usual G-type individuals. (2) A population from Caucasus exhibited a highly deviating GSL profile dominated by p -hydroxyphenethyl GSL that was insignificant in other accessions, as well as two GSLs investigated by NMR, m -hydroxyphenethylGSL and a partially identified m , p disubstituted hydroxy-methoxy derivative of phenethylGSL. Tandem HPLC–MS of seven NMR-identified desulfoGSLs was carried out and interpreted for increased certainty in peak identification and as a tool for partial structure elucidation. The distinct, geographically separated chemotypes and rare variants are discussed in relation to future taxonomic revision and the genetics and ecology of GSLs in B. vulgaris.

  • Consequences of combined herbivore feeding and pathogen infection for fitness of Barbarea vulgaris plants
    Oecologia, 2014
    Co-Authors: Tamara Mölken, Carl Erik Olsen, Vera Kuzina, Thomas Sundelin, Karen Rysbjerg Munk, Nicole M. Dam, Thure P. Hauser
    Abstract:

    Plants are often attacked by pathogens and insects. Their combined impact on plant performance and fitness depends on complicated three-way interactions and the plant’s ability to compensate for resource losses. Here, we evaluate the response of Barbarea vulgaris , a wild crucifer, to combined attack by an oomycete Albugo sp., a plant pathogen causing white rust, and a flea beetle, Phyllotreta nemorum. Plants from two B. vulgaris types that differ in resistance to P. nemorum were exposed to Albugo and P. nemorum alone and in combination and then monitored for pathogen infection, herbivore damage, defence compounds, nutritional quality, biomass and seed production. Albugo developed infections in the insect-resistant plants, whereas insect-susceptible plants were scarcely infected. Concentrations of Albugo DNA were higher in plants also exposed to herbivory; similarly, flea beetle larvae caused more damage on Albugo -infected plants. Concentrations of saponins and glucosinolates strongly increased when the plants were exposed to P. nemorum and when the insect-susceptible plants were exposed to Albugo , and some of these compounds increased even more in the combined treatment. The biomass of young insect-susceptible plants was lower following exposure to flea beetles, and the number of leaves of both plant types was negatively affected by combined exposure. After flowering, however, adult plants produced similar numbers of viable seeds, irrespective of treatment. Our findings support the concept that pathogens and herbivores can affect each other’s performance on a host plant and that the plant reacts by inducing specific and general defences. However, plants may be able to compensate for biomass loss from single and combined attacks over time.

  • Different Geographical Distributions of Two Chemotypes of Barbarea vulgaris that Differ in Resistance to Insects and a Pathogen
    Journal of chemical ecology, 2014
    Co-Authors: Stina Christensen, Christine Heimes, Niels Agerbirk, Carl Erik Olsen, Vera Kuzina, Thure P. Hauser
    Abstract:

    The interactions of plants with herbivores and pathogens have been suggested to drive the evolution of resistances in plants and in some cases new lineages and taxa. However, such divergence may require reproductive isolation, e.g., in allopatry. In the crucifer Barbarea vulgaris, some plants are resistant to the flea beetle Phyllotreta nemorum, due to production of specific saponins, whereas others are susceptible. Resistant and susceptible plants additionally differ in resistance to the pathogen Albugo candida, content of glucosinolates, and leaf pubescence, and they are genetically strongly divergent and partially reproductively incompatible. This suggests that at some point they were separated for a considerable length of time. Previously, the insect susceptible P-type had been described only from Denmark, Sweden, and Estonia, whereas the resistant G-type is widely distributed in Western Europe. Here, we tested whether the two plant types have divergent geographical distributions and maintain their distinct trait associations throughout their range. The insect-susceptible type was found in Russia, the Baltics, and parts of Fennoscandia, but not in Central Europe. In contrast, the insect resistant type was found from Finland and westwards. Their different trait associations were consistent within the two ranges. We therefore suggest that the two plant types diverged in allopatry at some time in the past, and evolved different resistances in response to local antagonists. The two plant types probably maintain their distinctness due to a hybridization barrier. Thus, the present distributions of the two types may be shaped by both historical processes and current differential biotic selection.

  • udp glycosyltransferases from the ugt73c subfamily in Barbarea vulgaris catalyze sapogenin 3 o glucosylation in saponin mediated insect resistance
    Plant Physiology, 2012
    Co-Authors: Jorg M Augustin, Sylvia Drok, Kazutsuka Sanmiya, Bekzod Khakimov, Esben Halkjaer Hansen, Jens Kvist Nielsen, Tetsuro Shinoda, Carl Erik Olsen, Vera Kuzina, Claus Thorn Ekstrom
    Abstract:

    Triterpenoid saponins are bioactive metabolites that have evolved recurrently in plants, presumably for defense. Their biosynthesis is poorly understood, as is the relationship between bioactivity and structure. Barbarea vulgaris is the only crucifer known to produce saponins. Hederagenin and oleanolic acid cellobioside make some B. vulgaris plants resistant to important insect pests, while other, susceptible plants produce different saponins. Resistance could be caused by glucosylation of the sapogenins. We identified four family 1 glycosyltransferases (UGTs) that catalyze 3-O-glucosylation of the sapogenins oleanolic acid and hederagenin. Among these, UGT73C10 and UGT73C11 show highest activity, substrate specificity and regiospecificity, and are under positive selection, while UGT73C12 and UGT73C13 show lower substrate specificity and regiospecificity and are under purifying selection. The expression of UGT73C10 and UGT73C11 in different B. vulgaris organs correlates with saponin abundance. Monoglucosylated hederagenin and oleanolic acid were produced in vitro and tested for effects on P. nemorum. 3-O-β-d-Glc hederagenin strongly deterred feeding, while 3-O-β-d-Glc oleanolic acid only had a minor effect, showing that hydroxylation of C23 is important for resistance to this herbivore. The closest homolog in Arabidopsis thaliana, UGT73C5, only showed weak activity toward sapogenins. This indicates that UGT73C10 and UGT73C11 have neofunctionalized to specifically glucosylate sapogenins at the C3 position and demonstrates that C3 monoglucosylation activates resistance. As the UGTs from both the resistant and susceptible types of B. vulgaris glucosylate sapogenins and are not located in the known quantitative trait loci for resistance, the difference between the susceptible and resistant plant types is determined at an earlier stage in saponin biosynthesis.

Thure P. Hauser - One of the best experts on this subject based on the ideXlab platform.

  • A hybridisation barrier between two evolutionary lineages of Barbarea vulgaris (Brassicaceae) that differ in biotic resistances
    Evolutionary Ecology, 2016
    Co-Authors: Stina Christensen, Karen Rysbjerg Munk, Helle Sørensen, Thure P. Hauser
    Abstract:

    Hybridisation barriers are likely to evolve during allopatric separation of populations, in parallel with divergent adaptation to different conditions in the two ranges. If the populations secondarily come into contact, limited interbreeding between them may affect the subsequent spread of the two lineages and their adaptations in the region of sympatry. Barbarea vulgaris include two genetically divergent lineages that differ in secondary metabolites and resistances to insects and a pathogen. The two plant types grow in different Eurasian ranges but co-occur in Denmark and neighbouring countries, posing the question why they have not merged and the resistances spread from one type into the range of the other. Here, we tested whether a hybridisation barrier contribute to this. Different proportions of plants of the two types were placed in net tents and pollinated by flies, and paternity of the resulting seeds determined with genetic markers. Lower proportions of fruits and seeds developed successfully in mixtures with higher proportions of heterotypic plants (i.e. of the other plant type). When combined with results on offspring paternity in a statistical analysis, we found that heterotypic pollen was much less successful in fertilizing embryos and that heterotypic seeds survived less frequently than the contypic. Mature F_1 hybrids in addition produced lower proportions of mature pollen. The two B. vulgaris plant types are thus separated by substantial prezygotic and postzygotic barriers, as strong as reported for crosses between closely related but taxonomically recognised plant species. This may explain why the two B. vulgaris types have not merged in sympatry and why genes for insect-resistance have not introgressed to any extent from one to the other.

  • Ecotypic differentiation of two sympatric chemotypes of Barbarea vulgaris (Brassicaceae) with different biotic resistances
    Plant Ecology, 2016
    Co-Authors: Christine Heimes, Niels Agerbirk, Tamara Mölken, Helle Sørensen, Thure P. Hauser
    Abstract:

    Evolution of ecotypic differentiation and maintenance of divergence in sympatry is more likely if populations occupy different habitats. Two genetically divergent chemotypes of Barbarea vulgaris (Brassicaceae) with contrasting insect and disease resistances (G- and P-type) occupy different geographical ranges in Eurasia but co-occur in Denmark. Here, they grow mostly in separate populations, posing the question why they have not merged. In a 2-year reciprocal transplant experiment, we tested whether the two plant types prefer different habitats and are adapted to these, possibly influenced by selection by herbivores. Vegetation and soil analyses indicated that the G-type occurs in slightly drier, less productive and more alkaline sites than the P-type. Plants planted at sites of their own chemotype had a higher biomass in the first year than plants of the non-resident chemotype, but were more damaged by beetle herbivory. This suggests that herbivores have adapted genetically or plastically to the resident chemotype. G-plants were less damaged by molluscs than P-plants, which may be caused by their content of saponins or glucosinolates. Levels of glucosinolates in siliques were higher in G-plants, but varied strongly among sites. Survival, reproduction and biomass in the second year did not differ between plants growing at sites of their own chemotype and plants of the other chemotype. Thus, the two chemotypes of B.   vulgaris are adapted to different habitats to some extent, which could contribute to maintain their differentiation in sympatry. Herbivory by some insects, however, may counteract this.

  • Interactive impacts of a herbivore and a pathogen on two resistance types of Barbarea vulgaris (Brassicaceae).
    Oecologia, 2014
    Co-Authors: Christine Heimes, Tamara Van Mölken, Jan Thiele, Thure P. Hauser
    Abstract:

    It is well known that pathogens and arthropod herbivores attacking the same host plant may affect each other. Little is known, however, about their combined impact on plant fitness, which may differ from simple additive expectations. In a 2-year common garden field experiment, we tested whether the pathogen Albugo sp. (white blister rust) and the herbivorous flea beetle Phyllotreta nemorum affected each other's performance on two resistance types (G-type and P-type) of the crucifer Barbarea vulgaris ssp. arcuata, and whether biomass, reproduction and survival of the plants were affected by interactive impacts of the antagonists. Most of the insect-resistant G-plants were severely affected by white rust, which reduced biomass and reproductive potential compared to the controls. However, when also exposed to flea beetles, biomass loss was mitigated in G-plants, even though apparent disease symptoms were not reduced. Most of the insect-susceptible P-plants were resistant to white rust; however, the number of flea beetle mines tended to increase in plants also exposed to Albugo, and biomass at the last harvest was slightly lower in the combined treatment. Thus, interactive impacts of the herbivore and pathogen differed between the two resistance types, with an antagonistic combined impact in G-plants, which lasted surprisingly long, and a slight synergistic impact in P-plants.

  • Consequences of combined herbivore feeding and pathogen infection for fitness of Barbarea vulgaris plants
    Oecologia, 2014
    Co-Authors: Tamara Mölken, Carl Erik Olsen, Vera Kuzina, Thomas Sundelin, Karen Rysbjerg Munk, Nicole M. Dam, Thure P. Hauser
    Abstract:

    Plants are often attacked by pathogens and insects. Their combined impact on plant performance and fitness depends on complicated three-way interactions and the plant’s ability to compensate for resource losses. Here, we evaluate the response of Barbarea vulgaris , a wild crucifer, to combined attack by an oomycete Albugo sp., a plant pathogen causing white rust, and a flea beetle, Phyllotreta nemorum. Plants from two B. vulgaris types that differ in resistance to P. nemorum were exposed to Albugo and P. nemorum alone and in combination and then monitored for pathogen infection, herbivore damage, defence compounds, nutritional quality, biomass and seed production. Albugo developed infections in the insect-resistant plants, whereas insect-susceptible plants were scarcely infected. Concentrations of Albugo DNA were higher in plants also exposed to herbivory; similarly, flea beetle larvae caused more damage on Albugo -infected plants. Concentrations of saponins and glucosinolates strongly increased when the plants were exposed to P. nemorum and when the insect-susceptible plants were exposed to Albugo , and some of these compounds increased even more in the combined treatment. The biomass of young insect-susceptible plants was lower following exposure to flea beetles, and the number of leaves of both plant types was negatively affected by combined exposure. After flowering, however, adult plants produced similar numbers of viable seeds, irrespective of treatment. Our findings support the concept that pathogens and herbivores can affect each other’s performance on a host plant and that the plant reacts by inducing specific and general defences. However, plants may be able to compensate for biomass loss from single and combined attacks over time.

  • Phylogeny of an Albugo sp. infecting Barbarea vulgaris in Denmark and its frequency of symptom development in natural populations of two evolutionary divergent plant types.
    Fungal biology, 2014
    Co-Authors: Tamara Van Mölken, Christine Heimes, Thure P. Hauser, Thomas Sundelin
    Abstract:

    Abstract The oomycete Albugo candida has long been considered a broad spectrum generalist pathogen, but recent studies suggest that it is diverged into several more specialized species in addition to the generalist Albugo candida sensu stricto . Whereas these species cause the disease white blister rust in many crucifer plants, asymptomatic endophytic infections may be important in the epidemiology of others. One of the plant species attacked by Albugo sp. is the wild crucifer Barbarea vulgaris ssp. arcuata , which is diverged into two phytochemically and genetically different types with different geographical distributions in Europe. These were previously shown to differ strongly in propensity to develop white rust upon controlled infections in the greenhouse. Here, we analyse the phylogenetic relatedness of this local Albugo sp. field isolate to other species and lines of Albugo spp., including others collected on B. vulgaris . We further ask whether the difference in incidence of white rust between the two types of B. vulgaris are also expressed in natural populations. Phylogenetically, the local Albugo sp. field isolate clustered tightly together with previously analysed samples from B. vulgaris , supporting that the Albugo sp. infecting B. vulgaris may indeed be an independent specialized species. White blister rust and Albugo DNA was only detected in two populations of the plant type that frequently develops symptoms upon controlled inoculations. The lack of white rust and Albugo sp. DNA in the other plant type may be due to either resistance, preventing infection, or asymptomatic infection of other tissues than leaves, which we analysed.

Peter W. De Jong - One of the best experts on this subject based on the ideXlab platform.

  • Polymorphism in a ¯ea beetle for the ability to use an atypical host plant
    2016
    Co-Authors: Peter W. De Jong, Jens Kvist Nielsen
    Abstract:

    ability to use Barbarea vulgaris R. Br. (Brassicaceae) as a host plant. The genetic factors in£uencing this ability show both sex-linked and autosomal inheritance. Evidence was found for the presence of major genes such as those found in earlier studies, but also of genes with a smaller e¡ect which have not previously been found. Although the ability to survive on B. vulgaris exists in most populations in eastern Denmark, it is usually at a low frequency. Beetles collected on B. vulgaris, however, usually produced larvae that survived on this plant. The inheritance and the abundance of the ability to use B. vulgaris are discussed in the context of the evolution of the interaction between P. nemorum and its atypical host plant

  • changes in frequencies of genes that enable phyllotreta nemorum to utilize its host plant Barbarea vulgaris vary in magnitude and direction as much within as between seasons
    Entomologia Experimentalis Et Applicata, 2012
    Co-Authors: Kim M C A Vermeer, Patrick Verbaarschot, Peter W. De Jong
    Abstract:

    The interaction between the flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae), and its host plants is well suited to study the dynamics of a geographic mosaic of (co)evolution. The flea beetle can either be resistant or susceptible to the defense of one of its host plants, Barbarea vulgaris R.Br. G-type (Brassicaceae). Previous findings suggested that the frequency of resistant beetles on host plants other than the G-type of B. vulgaris had decreased over time within the period of 1999–2003. In 2008 and 2009 new sampling was performed to investigate whether or not this decrease in frequency of resistance of the flea beetles formed a continuing trend and whether or not the frequency of resistant beetles also varies within the year. The frequency of resistant beetles on different host plants was determined during the reproductive season of the flea beetles in both years. Overall, the frequencies of resistant beetles on B. vulgaris (G-type) remained close to 100%, as found before, but those on other host plants did not consistently decrease across the years, in contrast to what had been suggested. Furthermore, the repeated sampling revealed that the frequency of resistant beetles differed significantly within a season. The present data show that relative frequencies of different resistance phenotypes of P. nemorum on other host plants than B. vulgaris (G-type) are highly dynamic, both within and across years. Therefore, monitoring the changes in these resistance frequencies should involve season-wide sampling efforts. Although the monitoring in this study does not provide an explanation for the observed dynamics, we propose a testable scenario.

  • pleiotropic effects associated with an allele enabling the flea beetle phyllotreta nemorum to use Barbarea vulgaris as a host plant
    Evolutionary Ecology, 2007
    Co-Authors: Kathleen Victoir, Casper J Breuker, Peter W. De Jong, Klaas Vrieling, Paul M. Brakefield
    Abstract:

    In the Danish region of Kvaerkeby, a mutation in an, as yet, unknown single autosomal gene has resulted in a dominant resistance (R-) allele in the flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae). It enables the beetle to overcome the defences of Barbarea vulgaris ssp. arcuata (Opiz.) Simkovics G-type (Brassicaceae) and use it as a host plant. In this study, we investigated the pleiotropic effects associated with the presence of this particular R-allele in female P. nemorum. These females had the R-allele backcrossed into the genetic background of non-resistant beetles. The effects were investigated under both favourable and stressful conditions (cold shock). The presence of the R-allele in a non-resistant genetic background caused a very high mortality in resistant individuals during the early stages of development under both conditions, but it did not affect the adult life-history traits longevity, body size and fecundity, under both conditions. Regardless of temperature treatment, resistant females in general were found to lay significantly more eggs. Developmental stability, as measured by tibia length fluctuating asymmetry, was not correlated with overall developmental stress in this study.

  • Pleiotropic effects associated with an allele enabling the flea beetle Phyllotreta nemorum to use Barbarea vulgaris as a host plant
    Evolutionary Ecology, 2007
    Co-Authors: Casper J Breuker, Kathleen Victoir, Peter W. De Jong, Klaas Vrieling, Paul M. Brakefield
    Abstract:

    In the Danish region of Kværkeby, a mutation in an, as yet, unknown single autosomal gene has resulted in a dominant resistance (R-) allele in the flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae). It enables the beetle to overcome the defences of Barbarea vulgaris ssp. arcuata (Opiz.) Simkovics G-type (Brassicaceae) and use it as a host plant. In this study, we investigated the pleiotropic effects associated with the presence of this particular R-allele in female P. nemorum . These females had the R-allele backcrossed into the genetic background of non-resistant beetles. The effects were investigated under both favourable and stressful conditions (cold shock). The presence of the R-allele in a non-resistant genetic background caused a very high mortality in resistant individuals during the early stages of development under both conditions, but it did not affect the adult life-history traits longevity, body size and fecundity, under both conditions. Regardless of temperature treatment, resistant females in general were found to lay significantly more eggs. Developmental stability, as measured by tibia length fluctuating asymmetry, was not correlated with overall developmental stress in this study.

  • aflp markers for the r gene in the flea beetle phyllotreta nemorum conferring resistance to defenses in Barbarea vulgaris
    Journal of Insect Science, 2005
    Co-Authors: Kathleen Victoir, Casper J Breuker, Peter W. De Jong, Paul M. Brakefield, Klaas Vrieling
    Abstract:

    A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) resistant to the defenses of the yellow rocket Barbarea vulgaris R.Br. (Brassicacea) and enables it to use it as a host plant in Denmark. In this study, genetic markers for an autosomal R-gene, inherited as a single, dominant locus in flea beetles from the Danish locality "Kvaerkeby" are described, and a genetic linkage map around this particular R-gene is constructed, using the technique of AFLP (Amplified Fragment Length Polymorphism). Cite this paper as: Breuker CJ, Victoir K, De Jong PW, Van der Meijden E, Brakefield PM, and Vrieling K. 2005. AFLP markers for the R-gene in the flea beetle, Phyllotreta nemorum, conferring resistance to defenses in Barbarea vulgaris. 9pp. Journal of Insect Science 5:38, available online: insectscience.org/5.38