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1.
J Exp Bot ; 74(18): 5752-5766, 2023 09 29.
Artículo en Inglés | MEDLINE | ID: mdl-37310189

RESUMEN

Root-knot nematodes (RKN) from the genus Meloidogyne induce the dedifferentiation of root vascular cells into giant multinucleate feeding cells. These feeding cells result from an extensive reprogramming of gene expression, and auxin is known to be a key player in their development. However, little is known about how the auxin signal is transmitted during giant cell development. Integrative analyses combining transcriptome and small non-coding RNA datasets with the specific sequencing of cleaved transcripts identified genes targeted by miRNAs in tomato (Solanum lycopersicum) galls. The two auxin-responsive transcription factors ARF8A and ARF8B, and their miRNA167 regulators, were identified as robust gene-miRNA pair candidates to be involved in the tomato response to M. incognita. Spatiotemporal expression analysis using promoter-ß-glucuronidase (GUS) fusions showed the up-regulation of ARF8A and ARF8B in RKN-induced feeding cells and surrounding cells. The generation and phenotyping of CRISPR (clustered regularly interspaced palindromic repeats) mutants demonstrated the role of ARF8A and ARF8B in giant cell development and allowed the characterization of their downstream regulated genes.


Asunto(s)
MicroARNs , Solanum lycopersicum , Tylenchoidea , Animales , Ácidos Indolacéticos/metabolismo , Solanum lycopersicum/genética , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Regulación de la Expresión Génica de las Plantas , MicroARNs/metabolismo , Tylenchoidea/fisiología
2.
New Phytol ; 236(1): 283-295, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35801827

RESUMEN

Root-knot nematodes (RKNs) are root endoparasites that induce the dedifferentiation of a few root cells and the reprogramming of their gene expression to generate giant hypermetabolic feeding cells. We identified two microRNA families, miR408 and miR398, as upregulated in Arabidopsis thaliana and Solanum lycopersicum roots infected by RKNs. In plants, the expression of these two conserved microRNA families is known to be activated by the SPL7 transcription factor in response to copper starvation. By combining functional approaches, we deciphered the network involving these microRNAs, their regulator and their targets. MIR408 expression was located within nematode-induced feeding cells like its regulator SPL7 and was regulated by copper. Moreover, infection assays with mir408 and spl7 knockout mutants or lines expressing targets rendered resistant to cleavage by miR398 demonstrated the essential role of the SPL7/MIR408/MIR398 module in the formation of giant feeding cells. Our findings reveal how perturbation of plant copper homeostasis, via the SPL7/MIR408/MIR398 module, modulates the development of nematode-induced feeding cells.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , MicroARNs , Tylenchoidea , Animales , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cobre/metabolismo , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica de las Plantas , MicroARNs/genética , MicroARNs/metabolismo , Raíces de Plantas/metabolismo , Factores de Transcripción/metabolismo , Tylenchoidea/fisiología
3.
BMC Genomics ; 22(1): 268, 2021 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-33853522

RESUMEN

BACKGROUND: Fertilization in flowering plants depends on the early contact and acceptance of pollen grains by the receptive papilla cells of the stigma. Deciphering the specific transcriptomic response of both pollen and stigmatic cells during their interaction constitutes an important challenge to better our understanding of this cell recognition event. RESULTS: Here we describe a transcriptomic analysis based on single nucleotide polymorphisms (SNPs) present in two Arabidopsis thaliana accessions, one used as female and the other as male. This strategy allowed us to distinguish 80% of transcripts according to their parental origins. We also developed a tool which predicts male/female specific expression for genes without SNP. We report an unanticipated transcriptional activity triggered in stigma upon incompatible pollination and show that following compatible interaction, components of the pattern-triggered immunity (PTI) pathway are induced on the female side. CONCLUSIONS: Our work unveils the molecular signatures of compatible and incompatible pollinations both at the male and female side. We provide invaluable resource and tools to identify potential new molecular players involved in pollen-stigma interaction.


Asunto(s)
Arabidopsis , Polinización , Arabidopsis/genética , Polen/genética , Polinización/genética , Transcriptoma
4.
PLoS Genet ; 13(6): e1006777, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28594822

RESUMEN

Root-knot nematodes (genus Meloidogyne) exhibit a diversity of reproductive modes ranging from obligatory sexual to fully asexual reproduction. Intriguingly, the most widespread and devastating species to global agriculture are those that reproduce asexually, without meiosis. To disentangle this surprising parasitic success despite the absence of sex and genetic exchanges, we have sequenced and assembled the genomes of three obligatory ameiotic and asexual Meloidogyne. We have compared them to those of relatives able to perform meiosis and sexual reproduction. We show that the genomes of ameiotic asexual Meloidogyne are large, polyploid and made of duplicated regions with a high within-species average nucleotide divergence of ~8%. Phylogenomic analysis of the genes present in these duplicated regions suggests that they originated from multiple hybridization events and are thus homoeologs. We found that up to 22% of homoeologous gene pairs were under positive selection and these genes covered a wide spectrum of predicted functional categories. To biologically assess functional divergence, we compared expression patterns of homoeologous gene pairs across developmental life stages using an RNAseq approach in the most economically important asexually-reproducing nematode. We showed that >60% of homoeologous gene pairs display diverged expression patterns. These results suggest a substantial functional impact of the genome structure. Contrasting with high within-species nuclear genome divergence, mitochondrial genome divergence between the three ameiotic asexuals was very low, signifying that these putative hybrids share a recent common maternal ancestor. Transposable elements (TE) cover a ~1.7 times higher proportion of the genomes of the ameiotic asexual Meloidogyne compared to the sexual relative and might also participate in their plasticity. The intriguing parasitic success of asexually-reproducing Meloidogyne species could be partly explained by their TE-rich composite genomes, resulting from allopolyploidization events, and promoting plasticity and functional divergence between gene copies in the absence of sex and meiosis.


Asunto(s)
Variación Genética , Genoma de los Helmintos , Hibridación Genética , Poliploidía , Reproducción Asexuada , Tylenchoidea/genética , Animales , Elementos Transponibles de ADN , Genoma Mitocondrial , Polimorfismo Genético , Selección Genética
5.
Mol Ecol ; 28(10): 2559-2572, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30964953

RESUMEN

Adaptation to changing environmental conditions represents a challenge to parthenogenetic organisms, and until now, how phenotypic variants are generated in clones in response to the selection pressure of their environment remains poorly known. The obligatory parthenogenetic root-knot nematode species Meloidogyne incognita has a worldwide distribution and is the most devastating plant-parasitic nematode. Despite its asexual reproduction, this species exhibits an unexpected capacity of adaptation to environmental constraints, for example, resistant hosts. Here, we used a genomewide comparative hybridization strategy to evaluate variations in gene copy numbers between genotypes of M. incognita resulting from two parallel experimental evolution assays on a susceptible vs. resistant host plant. We detected gene copy number variations (CNVs) associated with the ability of the nematodes to overcome resistance of the host plant, and this genetic variation may reflect an adaptive response to host resistance in this parthenogenetic species. The CNV distribution throughout the nematode genome is not random and suggests the occurrence of genomic regions more prone to undergo duplications and losses in response to the selection pressure of the host resistance. Furthermore, our analysis revealed an outstanding level of gene loss events in nematode genotypes that have overcome the resistance. Overall, our results support the view that gene loss could be a common class of adaptive genetic mechanism in response to a challenging new biotic environment in clonal animals.


Asunto(s)
Variaciones en el Número de Copia de ADN/genética , Evolución Molecular , Plantas/genética , Reproducción Asexuada/genética , Tylenchoidea/genética , Animales , Evolución Biológica , Genómica , Enfermedades de las Plantas , Fenómenos Fisiológicos de las Plantas/genética , Raíces de Plantas/genética , Plantas/parasitología , Tylenchoidea/patogenicidad , Tylenchoidea/fisiología
6.
Nature ; 500(7463): 453-7, 2013 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-23873043

RESUMEN

Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years. Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing. However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873), and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.


Asunto(s)
Evolución Biológica , Conversión Génica/genética , Genoma/genética , Reproducción Asexuada/genética , Rotíferos/genética , Animales , Transferencia de Gen Horizontal/genética , Genómica , Meiosis/genética , Modelos Biológicos , Tetraploidía
7.
BMC Genomics ; 19(1): 943, 2018 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-30563458

RESUMEN

BACKGROUND: Root-knot nematodes (RKN), genus Meloidogyne, are plant parasitic worms that have the ability to transform root vascular cylinder cells into hypertrophied, multinucleate and metabolically over-active feeding cells. Redifferentiation into feeding cells is the result of a massive transcriptional reprogramming of root cells targeted by RKN. Since RKN are able to induce similar feeding cells in roots of thousands of plant species, these worms are thought to manipulate essential and conserved plant molecular pathways. RESULTS: Small non-coding RNAs of uninfected roots and infected root galls induced by M. incognita from Arabidopsis thaliana were sequenced by high throughput sequencing. SiRNA populations were analysed by using the Shortstack algorithm. We identified siRNA clusters that are differentially expressed in infected roots and evidenced an over-representation of the 23-24 nt siRNAs in infected tissue. This size corresponds to heterochromatic siRNAs (hc-siRNAs) which are known to regulate expression of transposons and genes at the transcriptional level, mainly by inducing DNA methylation. CONCLUSIONS: Correlation of siRNA clusters expression profile with transcriptomic data identified several protein coding genes that are candidates to be regulated by siRNAs at the transcriptional level by RNA directed DNA methylation (RdDM) pathway either directly or indirectly via silencing of neighbouring transposable elements.


Asunto(s)
Arabidopsis/genética , Arabidopsis/parasitología , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/parasitología , ARN Interferente Pequeño/genética , Tylenchoidea/fisiología , Animales , Interacciones Huésped-Parásitos , Raíces de Plantas/genética , Raíces de Plantas/parasitología , Transcriptoma
8.
BMC Genomics ; 19(1): 321, 2018 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-29724186

RESUMEN

BACKGROUND: The renewed interest in epigenetics has led to the understanding that both the environment and individual lifestyle can directly interact with the epigenome to influence its dynamics. Epigenetic phenomena are mediated by DNA methylation, stable chromatin modifications and non-coding RNA-associated gene silencing involving specific proteins called epigenetic factors. Multiple organisms, ranging from plants to yeast and mammals, have been used as model systems to study epigenetics. The interactions between parasites and their hosts are models of choice to study these mechanisms because the selective pressures are strong and the evolution is fast. The asexually reproducing root-knot nematodes (RKN) offer different advantages to study the processes and mechanisms involved in epigenetic regulation. RKN genomes sequencing and annotation have identified numerous genes, however, which of those are involved in the adaption to an environment and potentially relevant to the evolution of plant-parasitism is yet to be discovered. RESULTS: Here, we used a functional comparative annotation strategy combining orthology data, mining of curated genomics as well as protein domain databases and phylogenetic reconstructions. Overall, we show that (i) neither RKN, nor the model nematode Caenorhabditis elegans possess any DNA methyltransferases (DNMT) (ii) RKN do not possess the complete machinery for DNA methylation on the 6th position of adenine (6mA) (iii) histone (de)acetylation and (de)methylation pathways are conserved between C. elegans and RKN, and the corresponding genes are amplified in asexually reproducing RKN (iv) some specific non-coding RNA families found in plant-parasitic nematodes are dissimilar from those in C. elegans. In the asexually reproducing RKN Meloidogyne incognita, expression data from various developmental stages supported the putative role of these proteins in epigenetic regulations. CONCLUSIONS: Our results refine previous predictions on the epigenetic machinery of model species and constitute the most comprehensive description of epigenetic factors relevant to the plant-parasitic lifestyle and/or asexual mode of reproduction of RKN. Providing an atlas of epigenetic factors in RKN is an informative resource that will enable researchers to explore their potential role in adaptation of these parasites to their environment.


Asunto(s)
Epigénesis Genética , Genoma , Plantas/parasitología , Reproducción Asexuada/genética , Tylenchoidea/genética , Animales , Proteínas Argonautas/clasificación , Proteínas Argonautas/genética , Caenorhabditis elegans/genética , ADN (Citosina-5-)-Metiltransferasas/clasificación , ADN (Citosina-5-)-Metiltransferasas/genética , Metilación de ADN , Histonas/genética , Histonas/metabolismo , Filogenia , Raíces de Plantas/parasitología , Procesamiento Proteico-Postraduccional/genética , Proteínas Protozoarias/clasificación , Proteínas Protozoarias/genética , ARN Pequeño no Traducido/genética
9.
New Phytol ; 217(2): 687-699, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29034957

RESUMEN

Root-knot nematodes, Meloidogyne spp., are obligate endoparasites that maintain a biotrophic relationship with their hosts. They infect roots as microscopic vermiform second-stage juveniles, and establish specialized feeding structures called 'giant-cells', from which they withdraw water and nutrients. The nematode effector proteins secreted in planta are key elements in the molecular dialogue of parasitism. Here, we compared Illumina RNA-seq transcriptomes for M. incognita obtained at various points in the lifecycle, and identified 31 genes more strongly expressed in parasitic stages than in preparasitic juveniles. We then selected candidate effectors for functional characterization. Quantitative real-time PCR and in situ hybridizations showed that the validated differentially expressed genes are predominantly specifically expressed in oesophageal glands of the nematode. We also soaked the nematodes in siRNA to silence these genes and to determine their role in pathogenicity. The silencing of the dorsal gland specific-Minc18876 and its paralogues resulted in a significant, reproducible decrease in the number of mature females with egg masses, demonstrating a potentially important role for the small glycine- and cysteine-rich effector MiSGCR1 in early stages of plant-nematode interaction. Finally, we report that MiSGCR1 suppresses plant cell death induced by bacterial or oomycete triggers of plant defense.


Asunto(s)
Interacciones Huésped-Parásitos , Nicotiana/parasitología , Parásitos/fisiología , Raíces de Plantas/parasitología , Tylenchoidea/fisiología , Secuencia de Aminoácidos , Animales , Muerte Celular , Esófago/metabolismo , Femenino , Perfilación de la Expresión Génica , Silenciador del Gen , Proteínas del Helminto/química , Proteínas del Helminto/metabolismo , Interacciones Huésped-Parásitos/genética , Masculino , Especificidad de Órganos/genética , Parásitos/genética , Células Vegetales/metabolismo , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/parasitología , Pseudomonas syringae/fisiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reproducibilidad de los Resultados , Nicotiana/microbiología , Transcriptoma/genética , Tylenchoidea/genética
10.
J Mol Evol ; 85(5-6): 234-245, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29075833

RESUMEN

The neurogenesis and neuronal functions in insect wing have been understudied mainly due to technical hindrances that have prevented electrophysiology studies for decades. The reason is that the nano-architecture of the wing chemosensory bristles hampers the receptors accessibility of odorants/tastants to receptors in fixed setup, whereas in nature, the wing flapping mixes these molecules in bristle lymph. In this report, we analyzed the transcriptome of the wing tissue of two species phylogenetically strongly divergent: Drosophila melanogaster a generic model for diptera order (complete metamorphosis) and the aphid acyrthosiphon pisum, representative of hemiptera order (incomplete metamorphosis) for which a conditional winged/wingless polyphenism is under control of population density and resources. The transcriptome shows that extensive gene networks involved in chemosensory perception are active in adult wing for both species. Surprisingly, the specific transcripts of genes that are commonly found in eye were present in Drosophila wing but not in aphid. The analysis reveals that in the aphid conditional wing, expressed genes show strong similarities with those in the gut epithelia. This suggests that the epithelial cell layer between the cuticle sheets is persistent at least in young aphid adult, whereas it disappears after emergence in Drosophila. Despite marked differences between the two transcriptomes, the results highlight the probable universalism of wing chemosensory function in the holometabolous and hemimetabolous orders of winged insects.


Asunto(s)
Alas de Animales/química , Alas de Animales/metabolismo , Animales , Áfidos/genética , Áfidos/metabolismo , Evolución Biológica , Células Quimiorreceptoras/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes , Genes de Insecto/genética , Hemípteros/genética , Insectos/genética , Neuronas , Filogenia , Transcriptoma , Alas de Animales/anatomía & histología
11.
New Phytol ; 216(3): 882-896, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28906559

RESUMEN

Root knot nematodes (RKN) are root parasites that induce the genetic reprogramming of vascular cells into giant feeding cells and the development of root galls. MicroRNAs (miRNAs) regulate gene expression during development and plant responses to various stresses. Disruption of post-transcriptional gene silencing in Arabidopsis ago1 or ago2 mutants decrease the infection rate of RKN suggesting a role for this mechanism in the plant-nematode interaction. By sequencing small RNAs from uninfected Arabidopsis roots and from galls 7 and 14 d post infection with Meloidogyne incognita, we identified 24 miRNAs differentially expressed in gall as putative regulators of gall development. Moreover, strong activity within galls was detected for five miRNA promoters. Analyses of nematode development in an Arabidopsis miR159abc mutant had a lower susceptibility to RKN, suggesting a role for the miR159 family in the plant response to M. incognita. Localization of mature miR159 within the giant and surrounding cells suggested a role in giant cell and gall. Finally, overexpression of miR159 in galls at 14 d post inoculation was associated with the repression of the miR159 target MYB33 which expression is restricted to the early stages of infection. Overall, these results implicate the miR159 in plant responses to RKN.


Asunto(s)
Arabidopsis/genética , Arabidopsis/parasitología , MicroARNs/genética , Tylenchoidea/patogenicidad , Animales , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Silenciador del Gen , Interacciones Huésped-Parásitos/genética , Raíces de Plantas/genética , Tumores de Planta/parasitología , Plantas Modificadas Genéticamente , Factores de Transcripción/genética
12.
PLoS Pathog ; 9(10): e1003745, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24204279

RESUMEN

Root-knot nematodes are globally the most aggressive and damaging plant-parasitic nematodes. Chemical nematicides have so far constituted the most efficient control measures against these agricultural pests. Because of their toxicity for the environment and danger for human health, these nematicides have now been banned from use. Consequently, new and more specific control means, safe for the environment and human health, are urgently needed to avoid worldwide proliferation of these devastating plant-parasites. Mining the genomes of root-knot nematodes through an evolutionary and comparative genomics approach, we identified and analyzed 15,952 nematode genes conserved in genomes of plant-damaging species but absent from non target genomes of chordates, plants, annelids, insect pollinators and mollusks. Functional annotation of the corresponding proteins revealed a relative abundance of putative transcription factors in this parasite-specific set compared to whole proteomes of root-knot nematodes. This may point to important and specific regulators of genes involved in parasitism. Because these nematodes are known to secrete effector proteins in planta, essential for parasitism, we searched and identified 993 such effector-like proteins absent from non-target species. Aiming at identifying novel targets for the development of future control methods, we biologically tested the effect of inactivation of the corresponding genes through RNA interference. A total of 15 novel effector-like proteins and one putative transcription factor compatible with the design of siRNAs were present as non-redundant genes and had transcriptional support in the model root-knot nematode Meloidogyne incognita. Infestation assays with siRNA-treated M. incognita on tomato plants showed significant and reproducible reduction of the infestation for 12 of the 16 tested genes compared to control nematodes. These 12 novel genes, showing efficient reduction of parasitism when silenced, constitute promising targets for the development of more specific and safer control means.


Asunto(s)
Genes de Helminto/fisiología , Enfermedades de las Plantas/parasitología , Tylenchoidea/genética , Animales , Estudio de Asociación del Genoma Completo , Humanos , Interferencia de ARN , Tylenchoidea/metabolismo
13.
Nat Commun ; 15(1): 773, 2024 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-38316773

RESUMEN

Using long-read sequencing, we assembled and unzipped the polyploid genomes of Meloidogyne incognita, M. javanica and M. arenaria, three of the most devastating plant-parasitic nematodes. We found the canonical nematode telomeric repeat to be missing in these and other Meloidogyne genomes. In addition, we find no evidence for the enzyme telomerase or for orthologs of C. elegans telomere-associated proteins, suggesting alternative lengthening of telomeres. Instead, analyzing our assembled genomes, we identify species-specific composite repeats enriched mostly at one extremity of contigs. These repeats are G-rich, oriented, and transcribed, similarly to canonical telomeric repeats. We confirm them as telomeric using fluorescent in situ hybridization. These repeats are mostly found at one single end of chromosomes in these species. The discovery of unusual and specific complex telomeric repeats opens a plethora of perspectives and highlights the evolutionary diversity of telomeres despite their central roles in senescence, aging, and chromosome integrity.


Asunto(s)
Tylenchida , Tylenchoidea , Animales , Caenorhabditis elegans/genética , Hibridación Fluorescente in Situ , Tylenchoidea/genética , Telómero/genética , Poliploidía
14.
Environ Sci Pollut Res Int ; 29(16): 23026-23040, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34799796

RESUMEN

Intercropping or assistant endophytes promote phytoremediation capacities of hyperaccumulators and enhance their tolerance to heavy metal (HM) stress. Findings from a previous study showed that intercropping the hyperaccumulator Sonchus asper (L.) Hill grown in HM-contaminated soils with maize improved the remediating properties and indicated an excluder-to-hyperaccumulator switched mode of action towards lead. In the current study, RNA-Seq analysis was conducted on Sonchus roots grown under intercropping or monoculture systems to explore the molecular events underlying this shift in lead sequestering strategy. The findings showed that intercropping only slightly affects S. asper transcriptome but significantly affects expression of root-associated microbial genomes. Further, intercropping triggers significant reshaping of endophytic communities associated with a 'root-to-shoot' transition of lead sequestration and improved phytoremediation capacities of S. asper. These findings indicate that accumulator activities of a weed are partially attributed to the root-associated microbiota, and a complex network of plant-microbe-plant interactions shapes the phytoremediation potential of S. asper. Analysis showed that intercropping may significantly change the structure of root-associated communities resulting in novel remediation properties, thus providing a basis for improving phytoremediation practices to restore contaminated soils.


Asunto(s)
Microbiota , Contaminantes del Suelo , Sonchus , Biodegradación Ambiental , Plomo/análisis , Raíces de Plantas/metabolismo , Rizosfera , Suelo , Contaminantes del Suelo/análisis
15.
Evol Appl ; 14(7): 1844-1866, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34295368

RESUMEN

Despite reproducing without sexual recombination, Meloidogyne incognita is an adaptive and versatile phytoparasitic nematode. This species displays a global distribution, can parasitize a large range of plants, and can overcome plant resistance in a few generations. The mechanisms underlying this adaptability remain poorly known. At the whole-genome level, only a few single nucleotide variations have been observed across different geographical isolates with distinct ranges of compatible hosts. Exploring other factors possibly involved in genomic plasticity is thus important. Transposable elements (TEs), by their repetitive nature and mobility, can passively and actively impact the genome dynamics. This is particularly expected in polyploid hybrid genomes such as the one of M. incognita. Here, we have annotated the TE content of M. incognita, analyzed the statistical properties of this TE landscape, and used whole-genome pool-seq data to estimate the mobility of these TEs across twelve geographical isolates, presenting variations in ranges of compatible host plants. DNA transposons are more abundant than retrotransposons, and the high similarity of TE copies to their consensus sequences suggests they have been at least recently active. We have identified loci in the genome where the frequencies of presence of a TE showed substantial variations across the different isolates. Overall, variations in TE frequencies across isolates followed their phylogenetic divergence, suggesting TEs participate in the species diversification. Compared with the M. incognita reference genome, we detected isolate and lineage-specific de novo insertion of some TEs, including within genic regions or in the upstream regulatory regions. We validated by PCR the insertion of some of these TEs inside genic regions, confirming TE movements have possible functional impacts. Overall, we show DNA transposons can drive genomic plasticity in M. incognita and their role in genome evolution of other parthenogenetic animal deserves further investigation.

16.
Genes (Basel) ; 12(5)2021 05 18.
Artículo en Inglés | MEDLINE | ID: mdl-34070210

RESUMEN

Root-knot nematodes (genus Meloidogyne) are the major contributor to crop losses caused by nematodes. These nematodes secrete effector proteins into the plant, derived from two sets of pharyngeal gland cells, to manipulate host physiology and immunity. Successful completion of the life cycle, involving successive molts from egg to adult, covers morphologically and functionally distinct stages and will require precise control of gene expression, including effector genes. The details of how root-knot nematodes regulate transcription remain sparse. Here, we report a life stage-specific transcriptome of Meloidogyne incognita. Combined with an available annotated genome, we explore the spatio-temporal regulation of gene expression. We reveal gene expression clusters and predicted functions that accompany the major developmental transitions. Focusing on effectors, we identify a putative cis-regulatory motif associated with expression in the dorsal glands, providing an insight into effector regulation. We combine the presence of this motif with several other criteria to predict a novel set of putative dorsal gland effectors. Finally, we show this motif, and thereby its utility, is broadly conserved across the Meloidogyne genus, and we name it Mel-DOG. Taken together, we provide the first genome-wide analysis of spatio-temporal gene expression in a root-knot nematode and identify a new set of candidate effector genes that will guide future functional analyses.


Asunto(s)
Expresión Génica/genética , Enfermedades de las Plantas/parasitología , Raíces de Plantas/parasitología , Regiones Promotoras Genéticas/genética , Tylenchoidea/genética , Animales , Estadios del Ciclo de Vida/genética , Infecciones por Secernentea/parasitología , Transcripción Genética/genética , Transcriptoma/genética
17.
Front Cell Dev Biol ; 9: 765690, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34938734

RESUMEN

In model organisms, epigenome dynamics underlies a plethora of biological processes. The role of epigenetic modifications in development and parasitism in nematode pests remains unknown. The root-knot nematode Meloidogyne incognita adapts rapidly to unfavorable conditions, despite its asexual reproduction. However, the mechanisms underlying this remarkable plasticity and their potential impact on gene expression remain unknown. This study provides the first insight into contribution of epigenetic mechanisms to this plasticity, by studying histone modifications in M. incognita. The distribution of five histone modifications revealed the existence of strong epigenetic signatures, similar to those found in the model nematode Caenorhabditis elegans. We investigated their impact on chromatin structure and their distribution relative to transposable elements (TE) loci. We assessed the influence of the chromatin landscape on gene expression at two developmental stages: eggs, and pre-parasitic juveniles. H3K4me3 histone modification was strongly correlated with high levels of expression for protein-coding genes implicated in stage-specific processes during M. incognita development. We provided new insights in the dynamic regulation of parasitism genes kept under histone modifications silencing. In this pioneering study, we establish a comprehensive framework for the importance of epigenetic mechanisms in the regulation of the genome expression and its stability in plant-parasitic nematodes.

18.
Front Genet ; 11: 557, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32582290

RESUMEN

Satellite DNA is a class of repetitive sequences that are organized in long arrays of tandemly repeated units in most eukaryotes. Long considered as selfish DNA, satellite sequences are now proposed to contribute to genome integrity. Despite their potential impact on the architecture and evolution of the genome, satellite DNAs have not been investigated in oomycetes due to the paucity of genomic data and the difficulty of assembling highly conserved satellite arrays. Yet gaining knowledge on the structure and evolution of genomes of oomycete pathogens is crucial to understanding the mechanisms underlying adaptation to their environment and to proposing efficient disease control strategies. A de novo assembly of the genome of Phytophthora parasitica, an important oomycete plant pathogen, led to the identification of several families of tandemly repeated sequences varying in size, copy number, and sequence conservation. Among them, two abundant families, designated as PpSat1 and PpSat2, displayed typical features of satellite DNA and were collectively designated as PpSat. These two satellite families differ by their length, sequence, organization, genomic environment, and evolutionary dynamics. PpSat1, but not PpSat2, presented homologs among oomycetes. This observation, as well as the characterization of transcripts of PpSat families, suggested that these satellite DNA families likely play a conserved role within this important group of pathogens.

19.
Sci Data ; 7(1): 324, 2020 10 05.
Artículo en Inglés | MEDLINE | ID: mdl-33020495

RESUMEN

Root-knot nematodes (genus Meloidogyne) are plant parasites causing huge economic loss in the agricultural industry and affecting severely numerous developing countries. Control methods against these plant pests are sparse, the preferred one being the deployment of plant cultivars bearing resistance genes against Meloidogyne species. However, M. enterolobii is not controlled by the resistance genes deployed in the crop plants cultivated in Europe. The recent identification of this species in Europe is thus a major concern. Here, we sequenced the genome of M. enterolobii using short and long-read technologies. The genome assembly spans 240 Mbp with contig N50 size of 143 kbp, enabling high-quality annotations of 59,773 coding genes, 4,068 non-coding genes, and 10,944 transposable elements (spanning 8.7% of the genome). We validated the genome size by flow cytometry and the structure, quality and completeness by bioinformatics metrics. This ensemble of resources will fuel future projects aiming at pinpointing the genome singularities, the origin, diversity, and adaptive potential of this emerging plant pest.


Asunto(s)
Genoma de los Helmintos , Tylenchoidea/genética , Animales , Europa (Continente) , Enfermedades de las Plantas/parasitología
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