The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Miguel A Aranda - One of the best experts on this subject based on the ideXlab platform.
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a cucumber green mottle mosaic virus vector for virus induced gene silencing in cucurbit plants
Plant Methods, 2020Co-Authors: Mei Liu, Zhiling Liang, Miguel A Aranda, Ni Hong, Liming Liu, Baoshan KangAbstract:Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiency. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits. Here, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69–300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged. These results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function, controlling viral pathogens or even performing resistance breeding in cucurbits. Moreover, this study will possess considerable important reference value for developing different viral vectors.
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a cucumber green mottle mosaic virus vector for virus induced gene silencing in cucurbit plants
bioRxiv, 2019Co-Authors: Mei Liu, Zhiling Liang, Miguel A Aranda, Ni Hong, Liming Liu, Baoshan KangAbstract:Abstract Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiencies. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits. Here, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69-300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged. These results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function in cucurbits. One sentence summary A CGMMV-based vector enables gene function studies in cucurbits, an extremely low efficiency species for genetic transformation.
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relative incidence spatial distribution and genetic diversity of cucurbit viruses in eastern spain
Annals of Applied Biology, 2013Co-Authors: M Juarez, Pilar Legua, C M Mengual, M A Kassem, Raquel Navarro Sempere, Pedro Gomez, Veronica Truniger, Miguel A ArandaAbstract:Viral diseases that could cause important economic losses often affect cucurbits, but only limited information on the incidence and spatial distribution of specific viruses is currently available. During the 2005 and 2006 growing seasons, systematic surveys were carried out in open field melon (Cucumis melo), squash and pumpkin (Cucurbita pepo), watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) crops of the Spanish Community of Valencia (eastern Spain), where several counties have a long standing tradition of cucurbit cultivation and production. Surveyed fields were chosen with no previous information as to their sanitation status, and samples were taken from plants that showed virus-like symptoms. Samples were analysed using molecular hybridisation to detect Beet pseudo-yellows virus (BPYV), Cucurbit aphid-borne yellows virus (CABYV), Cucumber mosaic virus (CMV), Cucumber vein yellowing virus (CVYV), Cucurbit yellow stunting disorder virus (CYSDV), Melon necrotic spot virus (MNSV), Papaya ring spot virus (PRSV), Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV). We collected 1767 samples from 122 independent field plots; out of these, approximately 94% of the samples were infected by at least one of these viruses. Percentages for the more frequently detected viruses were 35.8%, 27.0%, 16.5% and 7.2% for CABYV, WMV, PRSV and ZYMV, respectively, and significant deviations were found on the frequency distributions based on either the area or the host sampled. The number of multiple infections was high (average 36%), particularly for squash (more than 57%), with the most frequent combination being WMV + PRSV (12%) followed by WMV + CABYV (10%). Sequencing of WMV complementary DNA suggested that ‘emerging’ isolates have replaced the ‘classic’ ones, as described in southern regions of France, leading us to believe that cucurbit cultivation could be severely affected by these new, emerging isolates.
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determination of the melon chloroplast and mitochondrial genome sequences reveals that the largest reported mitochondrial genome in plants contains a significant amount of dna having a nuclear origin
BMC Genomics, 2011Co-Authors: Luis Rodriguezmoreno, Miguel A Aranda, Victor M Gonzalez, Andrej Benjak, Carmen M Marti, Pere Puigdomenech, Jordi GarciamasAbstract:The melon belongs to the Cucurbitaceae family, whose economic importance among vegetable crops is second only to Solanaceae. The melon has a small genome size (454 Mb), which makes it suitable for molecular and genetic studies. Despite similar nuclear and chloroplast genome sizes, cucurbits show great variation when their mitochondrial genomes are compared. The melon possesses the largest plant mitochondrial genome, as much as eight times larger than that of other cucurbits. The nucleotide sequences of the melon chloroplast and mitochondrial genomes were determined. The chloroplast genome (156,017 bp) included 132 genes, with 98 single-copy genes dispersed between the small (SSC) and large (LSC) single-copy regions and 17 duplicated genes in the inverted repeat regions (IRa and IRb). A comparison of the cucumber and melon chloroplast genomes showed differences in only approximately 5% of nucleotides, mainly due to short indels and SNPs. Additionally, 2.74 Mb of mitochondrial sequence, accounting for 95% of the estimated mitochondrial genome size, were assembled into five scaffolds and four additional unscaffolded contigs. An 84% of the mitochondrial genome is contained in a single scaffold. The gene-coding region accounted for 1.7% (45,926 bp) of the total sequence, including 51 protein-coding genes, 4 conserved ORFs, 3 rRNA genes and 24 tRNA genes. Despite the differences observed in the mitochondrial genome sizes of cucurbit species, Citrullus lanatus (379 kb), Cucurbita pepo (983 kb) and Cucumis melo (2,740 kb) share 120 kb of sequence, including the predicted protein-coding regions. Nevertheless, melon contained a high number of repetitive sequences and a high content of DNA of nuclear origin, which represented 42% and 47% of the total sequence, respectively. Whereas the size and gene organisation of chloroplast genomes are similar among the cucurbit species, mitochondrial genomes show a wide variety of sizes, with a non-conserved structure both in gene number and organisation, as well as in the features of the noncoding DNA. The transfer of nuclear DNA to the melon mitochondrial genome and the high proportion of repetitive DNA appear to explain the size of the largest mitochondrial genome reported so far.
Lori R Shapiro - One of the best experts on this subject based on the ideXlab platform.
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bacterial communities of herbivores and pollinators that have co evolved Cucurbita spp
bioRxiv, 2019Co-Authors: Lori R Shapiro, Joseph N Paulson, Erin D Scully, Jorge Rocha, Vanja Klepacceraj, Madison Youngblom, Angelica Cibrianjaramillo, Margarita M LopezuribeAbstract:Insects, like all animals, are exposed to diverse environmental microbes throughout their life cycle. Yet, we know little about variation in the microbial communities associated with the majority of wild, unmanaged insect species. Here, we use a 16S rRNA gene metabarcoding approach to characterize temporal and geographic variation in the gut bacterial communities of herbivores (Acalymma vittatum and A. trivittatum) and pollinators (Eucera (Peponapis) pruinosa) that have co-evolved with the plant genus Cucurbita (pumpkin, squash, zucchini and gourds). Overall, we find high variability in the composition of bacterial communities in squash bees and beetles collected from different geographic locations and different time points throughout a growing season. Still, many of the most common OTUs are shared in E. (P.) pruinosa, A. vittatum and A. trivittatum. This suggests these insects may be exposed to similar environmental microbial sources while foraging on the same genus of host plants, and that similar microbial taxa may aid in digestion of Cucurbita plant material. The striped cucumber beetle A. vittatum can also transmit Erwinia tracheiphila, the causal agent of bacterial wilt of cucurbits. We find that few field-collected A. vittatum individuals have detectable E. tracheiphila, and when this plant pathogen is detected, it comprises less than 1% of the gut bacterial community. Together, these results are consistent with previous studies showing that plant feeding insects have highly variable gut bacterial communities, and provides a first step towards understanding the spatiotemporal variation in the microbial communities associated with herbivores and pollinators that depend on Cucurbita host plants.
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an introduced crop plant is driving diversification of the virulent bacterial pathogen erwinia tracheiphila
Mbio, 2018Co-Authors: Lori R Shapiro, Joseph N Paulson, Brian J Arnold, Erin D Scully, Olga Zhaxybayeva, Naomi E Pierce, Jorge Rocha, Vanja Klepacceraj, Kristina HoltonAbstract:ABSTRACT Erwinia tracheiphila is the causal agent of bacterial wilt of cucurbits, an economically important phytopathogen affecting few cultivated Cucurbitaceae host plant species in temperate eastern North America. However, essentially nothing is known about E. tracheiphila population structure or genetic diversity. To address this shortcoming, a representative collection of 88 E. tracheiphila isolates was gathered from throughout its geographic range, and their genomes were sequenced. Phylogenomic analysis revealed three genetic clusters with distinct hrpT3SS virulence gene repertoires, host plant association patterns, and geographic distributions. Low genetic heterogeneity within each cluster suggests a recent population bottleneck followed by population expansion. We showed that in the field and greenhouse, cucumber (Cucumis sativus), which was introduced to North America by early Spanish conquistadors, is the most susceptible host plant species and the only species susceptible to isolates from all three lineages. The establishment of large agricultural populations of highly susceptible C. sativus in temperate eastern North America may have facilitated the original emergence of E. tracheiphila into cucurbit agroecosystems, and this introduced plant species may now be acting as a highly susceptible reservoir host. Our findings have broad implications for agricultural sustainability by drawing attention to how worldwide crop plant movement, agricultural intensification, and locally unique environments may affect the emergence, evolution, and epidemic persistence of virulent microbial pathogens. IMPORTANCEErwinia tracheiphila is a virulent phytopathogen that infects two genera of cucurbit crop plants, Cucurbita spp. (pumpkin and squash) and Cucumis spp. (muskmelon and cucumber). One of the unusual ecological traits of this pathogen is that it is limited to temperate eastern North America. Here, we complete the first large-scale sequencing of an E. tracheiphila isolate collection. From phylogenomic, comparative genomic, and empirical analyses, we find that introduced Cucumis spp. crop plants are driving the diversification of E. tracheiphila into multiple lineages. Together, the results from this study show that locally unique biotic (plant population) and abiotic (climate) conditions can drive the evolutionary trajectories of locally endemic pathogens in unexpected ways.
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An Introduced Crop Plant Is Driving Diversification of the Virulent Bacterial Pathogen Erwinia tracheiphila
American Society for Microbiology, 2018Co-Authors: Lori R Shapiro, Joseph N Paulson, Brian J Arnold, Erin D Scully, Olga Zhaxybayeva, Naomi E Pierce, Jorge Rocha, Kristina Holton, Vanja Klepac-ceraj, Roberto KolterAbstract:Erwinia tracheiphila is a virulent phytopathogen that infects two genera of cucurbit crop plants, Cucurbita spp. (pumpkin and squash) and Cucumis spp. (muskmelon and cucumber). One of the unusual ecological traits of this pathogen is that it is limited to temperate eastern North America. Here, we complete the first large-scale sequencing of an E. tracheiphila isolate collection. From phylogenomic, comparative genomic, and empirical analyses, we find that introduced Cucumis spp. crop plants are driving the diversification of E. tracheiphila into multiple lineages. Together, the results from this study show that locally unique biotic (plant population) and abiotic (climate) conditions can drive the evolutionary trajectories of locally endemic pathogens in unexpected ways.Erwinia tracheiphila is the causal agent of bacterial wilt of cucurbits, an economically important phytopathogen affecting few cultivated Cucurbitaceae host plant species in temperate eastern North America. However, essentially nothing is known about E. tracheiphila population structure or genetic diversity. To address this shortcoming, a representative collection of 88 E. tracheiphila isolates was gathered from throughout its geographic range, and their genomes were sequenced. Phylogenomic analysis revealed three genetic clusters with distinct hrpT3SS virulence gene repertoires, host plant association patterns, and geographic distributions. Low genetic heterogeneity within each cluster suggests a recent population bottleneck followed by population expansion. We showed that in the field and greenhouse, cucumber (Cucumis sativus), which was introduced to North America by early Spanish conquistadors, is the most susceptible host plant species and the only species susceptible to isolates from all three lineages. The establishment of large agricultural populations of highly susceptible C. sativus in temperate eastern North America may have facilitated the original emergence of E. tracheiphila into cucurbit agroecosystems, and this introduced plant species may now be acting as a highly susceptible reservoir host. Our findings have broad implications for agricultural sustainability by drawing attention to how worldwide crop plant movement, agricultural intensification, and locally unique environments may affect the emergence, evolution, and epidemic persistence of virulent microbial pathogens
Baoshan Kang - One of the best experts on this subject based on the ideXlab platform.
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a cucumber green mottle mosaic virus vector for virus induced gene silencing in cucurbit plants
Plant Methods, 2020Co-Authors: Mei Liu, Zhiling Liang, Miguel A Aranda, Ni Hong, Liming Liu, Baoshan KangAbstract:Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiency. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits. Here, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69–300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged. These results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function, controlling viral pathogens or even performing resistance breeding in cucurbits. Moreover, this study will possess considerable important reference value for developing different viral vectors.
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a cucumber green mottle mosaic virus vector for virus induced gene silencing in cucurbit plants
bioRxiv, 2019Co-Authors: Mei Liu, Zhiling Liang, Miguel A Aranda, Ni Hong, Liming Liu, Baoshan KangAbstract:Abstract Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiencies. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits. Here, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69-300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged. These results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function in cucurbits. One sentence summary A CGMMV-based vector enables gene function studies in cucurbits, an extremely low efficiency species for genetic transformation.
Belén Picó - One of the best experts on this subject based on the ideXlab platform.
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a major qtl located in chromosome 8 of Cucurbita moschata is responsible for resistance to tomato leaf curl new delhi virus
Frontiers in Plant Science, 2020Co-Authors: C Saez, Carmelo Lopez, Cecilia Martinez, Javier Monteropau, Cristina Esteras, Alicia Sifres, Jose Blanca, Maria Ferriol, Belén PicóAbstract:Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite whitefly transmitted begomovirus, responsible since 2013 of severe damages in cucurbit crops in Southeastern Spain. Zucchini (Cucurbita pepo) is the most affected species, but melon (Cucumis melo) and cucumber (Cucumis sativus) are also highly damaged by the infection. The virus has spread across Mediterranean basin and European countries, and integrated control measures are not being enough to reduce economic losses. The identification of resistance genes is required to develop resistant cultivars. In this assay, we studied the inheritance of the resistance to ToLCNDV previously identified in two Cucurbita moschata accessions. We generated segregating populations crossing both resistant pumpkins, an American improved cultivar Large Cheese (PI 604506) and an Indian landrace (PI 381814), with a susceptible C. moschata genotype (PI 419083). The analysis of symptoms and viral titers of all populations established the same monogenic recessive genetic control in both resistant accessions, and the allelism tests suggest the occurrence of alleles of the same locus. By genotyping with a single nucleotide polymorphism (SNP) collection evenly distributed along the C. moschata genome, a major quantitative trait locus (QTL) was identified in chromosome 8 controlling resistance to ToLCNDV. This major QTL was also confirmed in the interspecific C. moschata × C. pepo segregating populations, although C. pepo genetic background affected the resistance level. Molecular markers here identified, linked to the ToLCNDV resistance locus, are highly valuable for zucchini breeding programs, allowing the selection of improved commercial materials. The duplication of the candidate region within the C. moschata genome was studied, and genes with paralogs or single-copy genes were identified. Its synteny with the region of chromosome 17 of the susceptible C. pepo revealed an INDEL including interesting candidate genes. The chromosome 8 candidate region of C. moschata was also syntenic to the region in chromosome 11 of melon, previously described as responsible of ToLCNDV resistance. Common genes in the candidate regions of both cucurbits, with high- or moderate-impact polymorphic SNPs between resistant and susceptible C. moschata accessions, are interesting to study the mechanisms involved in this recessive resistance.
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a watermelon mosaic virus clone tagged with the yellow visual maker phytoene synthase facilitates scoring infectivity in melon breeding programs
European Journal of Plant Pathology, 2019Co-Authors: Veronica Aragones, Belén Picó, Ana Maria Perezdecastro, Teresa Cordero, Jaime Cebollacornejo, Carmelo Lopez, Joseantonio DarosAbstract:Watermelon mosaic virus (WMV), a plus-strand RNA virus that belongs to the family Potyviridae, is one of the most damaging viruses that infect cucurbit crops. However, isolates of this species frequently induce mild symptoms, which makes difficult to manage the disease in the field and breeding programs. A new generation of marker genes has been recently developed to visually track plant virus infection. Virus-mediated expression of the Pantoea ananatis phytoene synthase (crtB) induces accumulation in infected tissues of pigmented carotenoids that can be readily detected by the naked eye. Here we investigated whether this visual marker may facilitate visual diagnosis of WMV infection in cucurbits. First, we cloned a mild WMV isolate (WMV-Vera) and built a recombinant clone that expresses crtB (WMV-crtB). Next, we inoculated a series of cucurbit cultivars frequently used in breeding programs. We observed that WMV-mediated expression of crtB helps to visually score infection in two susceptible and highly appreciated melon cultivars, such as Pinonet Piel de Sapo and Vedrantais, but not in susceptible Cucurbita spp. cultivars. An increase in yellow pigmentation was experimentally confirmed in susceptible melon cultivars by measuring the Hue angle using a solid colorimeter. Carotenoid analyses in infected tissues explained why the visual crtB marker performs better in susceptible melon than in Cucurbita spp. cultivars. These results support that the visual marker crtB may facilitate visual diagnosis of WMV infection in melon breeding programs.
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transcriptome characterization and high throughput ssrs and snps discovery in Cucurbita pepo Cucurbitaceae
BMC Genomics, 2011Co-Authors: Jose Blanca, Joaquin Canizares, Cristina Roig, Pello Ziarsolo, Fernando Nuez, Belén PicóAbstract:Cucurbita pepo belongs to the Cucurbitaceae family. The "Zucchini" types rank among the highest-valued vegetables worldwide, and other C. pepo and related Cucurbita spp., are food staples and rich sources of fat and vitamins. A broad range of genomic tools are today available for other cucurbits that have become models for the study of different metabolic processes. However, these tools are still lacking in the Cucurbita genus, thus limiting gene discovery and the process of breeding. We report the generation of a total of 512,751 C. pepo EST sequences, using 454 GS FLX Titanium technology. ESTs were obtained from normalized cDNA libraries (root, leaves, and flower tissue) prepared using two varieties with contrasting phenotypes for plant, flowering and fruit traits, representing the two C. pepo subspecies: subsp. pepo cv. Zucchini and subsp. ovifera cv Scallop. De novo assembling was performed to generate a collection of 49,610 Cucurbita unigenes (average length of 626 bp) that represent the first transcriptome of the species. Over 60% of the unigenes were functionally annotated and assigned to one or more Gene Ontology terms. The distributions of Cucurbita unigenes followed similar tendencies than that reported for Arabidopsis or melon, suggesting that the dataset may represent the whole Cucurbita transcriptome. About 34% unigenes were detected to have known orthologs of Arabidopsis or melon, including genes potentially involved in disease resistance, flowering and fruit quality. Furthermore, a set of 1,882 unigenes with SSR motifs and 9,043 high confidence SNPs between Zucchini and Scallop were identified, of which 3,538 SNPs met criteria for use with high throughput genotyping platforms, and 144 could be detected as CAPS. A set of markers were validated, being 80% of them polymorphic in a set of variable C. pepo and C. moschata accessions. We present the first broad survey of gene sequences and allelic variation in C. pepo, where limited prior genomic information existed. The transcriptome provides an invaluable new tool for biological research. The developed molecular markers are the basis for future genetic linkage and quantitative trait loci analysis, and will be essential to speed up the process of breeding new and better adapted squash varieties.
Kristina Holton - One of the best experts on this subject based on the ideXlab platform.
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an introduced crop plant is driving diversification of the virulent bacterial pathogen erwinia tracheiphila
Mbio, 2018Co-Authors: Lori R Shapiro, Joseph N Paulson, Brian J Arnold, Erin D Scully, Olga Zhaxybayeva, Naomi E Pierce, Jorge Rocha, Vanja Klepacceraj, Kristina HoltonAbstract:ABSTRACT Erwinia tracheiphila is the causal agent of bacterial wilt of cucurbits, an economically important phytopathogen affecting few cultivated Cucurbitaceae host plant species in temperate eastern North America. However, essentially nothing is known about E. tracheiphila population structure or genetic diversity. To address this shortcoming, a representative collection of 88 E. tracheiphila isolates was gathered from throughout its geographic range, and their genomes were sequenced. Phylogenomic analysis revealed three genetic clusters with distinct hrpT3SS virulence gene repertoires, host plant association patterns, and geographic distributions. Low genetic heterogeneity within each cluster suggests a recent population bottleneck followed by population expansion. We showed that in the field and greenhouse, cucumber (Cucumis sativus), which was introduced to North America by early Spanish conquistadors, is the most susceptible host plant species and the only species susceptible to isolates from all three lineages. The establishment of large agricultural populations of highly susceptible C. sativus in temperate eastern North America may have facilitated the original emergence of E. tracheiphila into cucurbit agroecosystems, and this introduced plant species may now be acting as a highly susceptible reservoir host. Our findings have broad implications for agricultural sustainability by drawing attention to how worldwide crop plant movement, agricultural intensification, and locally unique environments may affect the emergence, evolution, and epidemic persistence of virulent microbial pathogens. IMPORTANCEErwinia tracheiphila is a virulent phytopathogen that infects two genera of cucurbit crop plants, Cucurbita spp. (pumpkin and squash) and Cucumis spp. (muskmelon and cucumber). One of the unusual ecological traits of this pathogen is that it is limited to temperate eastern North America. Here, we complete the first large-scale sequencing of an E. tracheiphila isolate collection. From phylogenomic, comparative genomic, and empirical analyses, we find that introduced Cucumis spp. crop plants are driving the diversification of E. tracheiphila into multiple lineages. Together, the results from this study show that locally unique biotic (plant population) and abiotic (climate) conditions can drive the evolutionary trajectories of locally endemic pathogens in unexpected ways.
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An Introduced Crop Plant Is Driving Diversification of the Virulent Bacterial Pathogen Erwinia tracheiphila
American Society for Microbiology, 2018Co-Authors: Lori R Shapiro, Joseph N Paulson, Brian J Arnold, Erin D Scully, Olga Zhaxybayeva, Naomi E Pierce, Jorge Rocha, Kristina Holton, Vanja Klepac-ceraj, Roberto KolterAbstract:Erwinia tracheiphila is a virulent phytopathogen that infects two genera of cucurbit crop plants, Cucurbita spp. (pumpkin and squash) and Cucumis spp. (muskmelon and cucumber). One of the unusual ecological traits of this pathogen is that it is limited to temperate eastern North America. Here, we complete the first large-scale sequencing of an E. tracheiphila isolate collection. From phylogenomic, comparative genomic, and empirical analyses, we find that introduced Cucumis spp. crop plants are driving the diversification of E. tracheiphila into multiple lineages. Together, the results from this study show that locally unique biotic (plant population) and abiotic (climate) conditions can drive the evolutionary trajectories of locally endemic pathogens in unexpected ways.Erwinia tracheiphila is the causal agent of bacterial wilt of cucurbits, an economically important phytopathogen affecting few cultivated Cucurbitaceae host plant species in temperate eastern North America. However, essentially nothing is known about E. tracheiphila population structure or genetic diversity. To address this shortcoming, a representative collection of 88 E. tracheiphila isolates was gathered from throughout its geographic range, and their genomes were sequenced. Phylogenomic analysis revealed three genetic clusters with distinct hrpT3SS virulence gene repertoires, host plant association patterns, and geographic distributions. Low genetic heterogeneity within each cluster suggests a recent population bottleneck followed by population expansion. We showed that in the field and greenhouse, cucumber (Cucumis sativus), which was introduced to North America by early Spanish conquistadors, is the most susceptible host plant species and the only species susceptible to isolates from all three lineages. The establishment of large agricultural populations of highly susceptible C. sativus in temperate eastern North America may have facilitated the original emergence of E. tracheiphila into cucurbit agroecosystems, and this introduced plant species may now be acting as a highly susceptible reservoir host. Our findings have broad implications for agricultural sustainability by drawing attention to how worldwide crop plant movement, agricultural intensification, and locally unique environments may affect the emergence, evolution, and epidemic persistence of virulent microbial pathogens