Recent molecular evidence suggest that three tetraploids A. Alternatively, the hexaploid D genome was inferred to originate from C-genome A. Molecular and genome size analyses suggest that D-genome diploids hybridized with AC-genome tetraploids followed by chromosome doubling to form hexaploids 12, 13. Molecular data support a close relationship between D and A genomes 11. The A- and C-genome diploids are distinguished by the structural differentiation of isobrachial and heterobrachial chromosomes 8, while the B and D genomes are not found in any extant diploids 9, 10. The genus forms a polyploid series ranging from A- and C-genome diploids (2 x = 14), AB- and A’C (DC)-genome tetraploids (4 x = 28), to ACD-genome hexaploids (6 x = 42) 7. Based on glume shape, lemma apex, and the insertion of lemmatal awn, seven sections have been recognized for Avena: Avenotrichon (Holub) Baum, Ventricosa Baum ex Romero-Zarco, Agraria Baum, Tenuicarpa Baum, Ethiopica Baum, Pachycarpa Baum, and Avena 6. 29 species exhibiting considerable morphological and ecological diversity in the Mediterranean Basin, Eastern Africa, Europe, Asia, and the Americas 4, 5. This approach does require sufficient depth of sequencing and the identification of paralogues produced by gene duplication events 3. Phylogenetic evidence from nuclear loci has accumulated to identify allopolyploidy events because they produce characteristic double-labelled phylograms in which allopolyploids appear more than once 2. Genome duplication following hybridization (allopolyploidy) is common among flowering plants, and is found in nearly a quarter of Poaceae that provide crops and fuel worldwide 1. This newly-resolved infrageneric phylogenetic framework represents a major step forward in understanding the origin of the cultivated oat. Our results suggest that polyploidy, lineage divergence, and complex reticulate evolution have occurred in Avena, exemplifying the long-term persistence of tetraploids and the multiple origins of hexaploids related to paleoclimatic oscillations during the Miocene-Pliocene interval in the circum-Mediterranean region. These periods coincided with the mild seasonal climatic contrasts and the Mediterranean climate established in the Mediterranean Basin. sativa lineages were dated to the late Miocene to Pliocene. Avena) were estimated to be in the early to middle Miocene, and the A. Ventricosa Baum ex Romero-Zarco and Avena sect. The crown ages of two infrageneric lineages ( Avena sect. ![]() The evolution of cultivated oat ( Avena sativa L.) and its close relatives was inferred to have involved ancient allotetraploidy and subsequent recent allohexaploidy events. (Poaceae) and the outgroups were used for maximum likelihood and Bayesian analyses. Sequence data of three nuclear genes and three plastid DNA fragments from 109 accessions of Avena L. Journal of Antimicrobial Chemotherapy Oxford University Press Understanding the diversification of polyploid crops in the circum-Mediterranean region is a challenging issue in evolutionary biology. Resistance to imipenem, meropenem and ticarcillin/clavulanate has been introduced into A85 by pA85-3, a repAci6 conjugative plasmid carrying Tn2006 in AbaR4. A85 is sequence type ST126 (Oxford scheme) and carries a novel KL15 capsule locus and the OC元 outer core locus.ConclusionsA85 represents a new GC1 lineage identified by the novel capsule locus but retains AbaR3 carrying genes for resistance to older antibiotics. A85 also contains two small cryptic plasmids of 2.7 and 8.7 kb. An 86 335 bp repAci6 plasmid, pA85-3, carrying blaOXA-23 in Tn2006 in AbaR4, was shown to transfer imipenem, meropenem and ticarcillin/clavulanate resistance into a susceptible recipient. A second copy of the ampC gene in Tn6168 confers cephalosporin resistance and the gyrA and parC genes have mutations leading to fluoroquinolone resistance. Genes for resistance to older antibiotics are in the chromosome, in an AbaR3 resistance island. Conjugation experiments were conducted.ResultsThe sporadic GC1 isolate A85, recovered in 2003, was extensively resistant, exhibiting resistance to imipenem, meropenem and ticarcillin/clavulanate, to cephalosporins and fluoroquinolones and to the older antibiotics gentamicin, kanamycin and neomycin, sulfamethoxazole, trimethoprim and tetracycline. Sequences were compared with ones in GenBank. PCR was used to assemble relevant contigs. ![]() baumannii global clone 1 (GC1) isolate.MethodsThe genome of the extensively antibiotic-resistant GC1 isolate A85 harbouring blaOXA-23 in Tn2006 was sequenced using Illumina HiSeq, and the reads were used to generate a de novo assembly. ![]() ObjectivesTo locate the acquired blaOXA-23 carbapenem resistance gene in an Australian A. A conjugative plasmid carrying the carbapenem resistance gene blaOXA-23 in AbaR4 in an extensively resistant GC1 Acinetobacter baumannii isolate A conjugative plasmid carrying the carbapenem resistance gene blaOXA-23 in AbaR4 in an.
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