RESUMO
Although RNA viruses evolved the mechanisms of specific encapsidation, miss-packaging of cellular RNAs has been reported in such RNA virus systems as flock house virus or cucumber necrosis virus. To find out if brome mosaic virus (BMV), a tripartite RNA virus, can package cellular RNAs, BMV was propagated in barley and in Nicotiana benthamiana hosts, purified by cesium chloride (CsCl) gradient ultracentrifugation followed by nuclease treatment to remove any contaminating cellular (host) RNAs. The extracted virion RNA was then sequenced by using next-generation sequencing (NGS RNA-Seq) with the Illumina protocol. Bioinformatic analysis revealed the content of host RNAs ranging from 0.07% for BMV extracted from barley to 0.10% for the virus extracted from N. benthamiana. The viruses from two sources appeared to co-encapsidate different patterns of host-RNAs, including ribosomal RNAs (rRNAs), messenger RNAs (mRNAs) but also mitochondrial and plastid RNAs and, interestingly, transposable elements, both transposons and retrotransposons. Our data reveal that BMV virions can carry host RNAs, having a potential to mediate horizontal gene transfer (HGT) in plants.
Assuntos
Bromovirus/genética , Sequenciamento de Nucleotídeos em Larga Escala , RNA Viral/genética , Montagem de Vírus/genética , Proteínas do Capsídeo/genética , Elementos de DNA Transponíveis/genética , Transferência Genética Horizontal , Hordeum/virologia , Interações Hospedeiro-Patógeno/genética , RNA Mensageiro/genética , Nicotiana/virologia , Vírion/genéticaRESUMO
Paniceae demonstrate unique variability of photosynthetic physiology and anatomy, including both non-Kranz and Kranz species and all subtypes of the latter. This variability suggests hypotheses of independent origin or reversals (e.g., from C(4) to C(3)). These hypotheses can be tested by phylogenetic analysis of independent molecular characters. The molecular phylogeny of 57 species of Paniceae was explored using sequences from the grass-specific insert found in the plastid locus rpoC2. Phylogenetic analyses confirmed some long-recognized alliances in Paniceae, some recent molecular phylogenetic results, and suggested new relationships. Broadly, Paniceae were found to be paraphyletic with Andropogoneae, Panicum was found to be polyphyletic, and Oplismenus hirtellus was resolved as the sister group to the remaining ingroup species. A particularly well-supported clade in the rpoC2 tree included four genera with non-Kranz species and three with distinctively keeled paleas. As previously suggested, the PCK (phosphoenol pyruvate carboxykinase) C(4) subtype arose once within Paniceae. All clades with non-Kranz species had Kranz ancestors or sister taxa suggesting repeated loss of the Kranz syndrome.
RESUMO
Phylogenies based on nine prokaryotic catalase sequences demonstrate no relationship to phylogenies based on rDNA sequences or other known criteria. When this observation is considered together with the monophyletic relationship observed for eukaryotic catalase sequences, it seems likely that the catalase gene sequence has migrated repeatedly from eukaryotes to prokaryotes.
Assuntos
Bactérias/genética , Catalase/genética , Genes Bacterianos , Filogenia , Bactérias/enzimologia , DNA Ribossômico/genética , Células Eucarióticas/enzimologiaRESUMO
Phylogenetic analyses of rbcL sequence data from grasses are presented, extending the work of an earlier study. Based on molecular evidence that Joinvilleaceae and Restionaceae are closely allied to Poaceae, species from these families and from a distantly related dicot were variously employed as outgroups and analyzed with 23 species of Poaceae using the parsimony method. Measures of support were determined. The terminal portion of the tree was invariant in all analyses. Outgroup selection affected the basal topology of the tree with somewhat different measures of support for the deeper branches of the tree. When the outgroup was the dicot, pooid grasses made up the basal clade. When the outgroup was Joinvilleaceae or Restionaceae, species of Bambusoideae were basalmost. Increased sampling did not result in a marked increase in support of the rbcL data for the earliest branching events.
Assuntos
Filogenia , Plantas/classificação , Plantas/genética , Ribulose-Bifosfato Carboxilase/genética , Sequência de Bases , Primers do DNA , Dados de Sequência Molecular , Poaceae/classificação , Poaceae/genética , Reação em Cadeia da PolimeraseRESUMO
The identity of the oldest lineage of monocotyledons is a subject of debate. Alternative interpretations of morphological homologies are variously consistent with proposals that species of Alismatanae, Dioscoreales, or Melanthiales were the earliest descendants of the first monocotyledons. We present phylogenetic analyses based on DNA sequences of the plastid locus rbcL in which Acorus calamus, an herb with unspecialized floral features and of uncertain affinities, is supported as a member of the oldest extant lineage of monocotyledons. This conclusion is consistent with a substantial body of morphological, anatomical, and embryological evidence and offers an explanation for the failure to identify any close relationship between Acorus and other genera.
