RESUMO
The ability of herbivorous beetles from the superfamilies Chrysomeloidea and Curculionoidea to degrade plant cell wall polysaccharides has only recently begun to be appreciated. The presence of plant cell wall degrading enzymes (PCWDEs) in the beetle's digestive tract makes this degradation possible. Sequences encoding these beetle-derived PCWDEs were originally identified from transcriptomes and strikingly resemble those of saprophytic and phytopathogenic microorganisms, raising questions about their origin; e.g. are they insect- or microorganism-derived? To demonstrate unambiguously that the genes encoding PCWDEs found in beetle transcriptomes are indeed of insect origin, we generated a bacterial artificial chromosome library from the genome of the leaf beetle Chrysomela tremula, containing 18 432 clones with an average size of 143 kb. After hybridizing this library with probes derived from 12 C. tremulaâ PCWDE-encoding genes and sequencing the positive clones, we demonstrated that the latter genes are encoded by the insect's genome and are surrounded by genes possessing orthologues in the genome of Tribolium castaneum as well as in three other beetle genomes. Our analyses showed that although the level of overall synteny between C. tremula and T. castaneum seems high, the degree of microsynteny between both species is relatively low, in contrast to the more closely related Colorado potato beetle.
Assuntos
Besouros/enzimologia , Besouros/genética , Sequência de Aminoácidos , Animais , Cromossomos Artificiais Bacterianos , Genoma , Genoma de Inseto , Dados de Sequência Molecular , Filogenia , Sintenia , TranscriptomaRESUMO
The Afrotropical mosquito Anopheles gambiae sensu stricto, a major vector of malaria, is currently undergoing speciation into the M and S molecular forms. These forms have diverged in larval ecology and reproductive behavior through unknown genetic mechanisms, despite considerable levels of hybridization. Previous genome-wide scans using gene-based microarrays uncovered divergence between M and S that was largely confined to gene-poor pericentromeric regions, prompting a speciation-with-ongoing-gene-flow model that implicated only about 3% of the genome near centromeres in the speciation process. Here, based on the complete M and S genome sequences, we report widespread and heterogeneous genomic divergence inconsistent with appreciable levels of interform gene flow, suggesting a more advanced speciation process and greater challenges to identify genes critical to initiating that process.
Assuntos
Anopheles/genética , Especiação Genética , Genoma de Inseto , Animais , Anopheles/classificação , Evolução Molecular , Feminino , Fluxo Gênico , Masculino , Modelos Genéticos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Downy mildew, caused by Plasmopara halstedii, is one of the most destructive diseases in cultivated sunflower (Helianthus annuus L.). The dominant resistance locus Pl(ARG) originates from silverleaf sunflower (H. argophyllus Torrey and Gray) and confers resistance to all known races of P. halstedii. We mapped Pl(ARG) on linkage group (LG) 1 of (cms)HA342 × ARG1575-2, a population consisting of 2,145 F(2) individuals. Further, we identified resistance gene candidates (RGCs) that cosegregated with Pl(ARG) as well as closely linked flanking markers. Markers from the target region were mapped with higher resolution in NDBLOS(sel) × KWS04, a population consisting of 2,780 F(2) individuals that does not segregate for Pl(ARG). A large-insert sunflower bacterial artificial chromosome (BAC) library was screened with overgo probes designed for markers RGC52 and RGC151, which cosegregated with Pl(ARG). Two RGC-containing BAC contigs were anchored to the Pl(ARG) region on LG 1.
Assuntos
Loci Gênicos/genética , Helianthus/genética , Helianthus/microbiologia , Imunidade Inata/genética , Peronospora/fisiologia , Mapeamento Físico do Cromossomo/métodos , Doenças das Plantas/imunologia , Sequência de Bases , Segregação de Cromossomos/genética , Cromossomos Artificiais Bacterianos/genética , Cruzamentos Genéticos , Biblioteca Gênica , Genes de Plantas/genética , Ligação Genética , Marcadores Genéticos , Testes Genéticos , Genética Populacional , Haplótipos/genética , Helianthus/imunologia , Mutagênese Insercional/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas , Recombinação Genética/genéticaRESUMO
The species of the genus Nasonia possess qualities that make them excellent candidates for genetic and genomic studies. To increase the wealth of genomic resources for the genus we constructed publicly available bacterial artificial chromosome (BAC) libraries for Nasonia vitripennis and Nasonia giraulti. Libraries have 36 864 clones each, empty-vector contents of approximately 2% and average insert sizes of 113.1 and 97.7 Kb, respectively, representing 12 and 11 genome equivalents. The N. vitripennis library was used for genome sequence assembly and in efforts at positional cloning of a developmental gene. The genome assembly of N. vitripennis is currently composed on 6181 un-joined scaffolds. These BAC libraries can be used to identify and close regions between scaffolds of the genome assemblies of both species.