Abdelhameed Elameen
Research Scientist
Authors
Live Lingaas Nesse Kristin Forfang Jannice Schau Slettemeås Snorre Hagen Marianne Sunde Abdelhameed Elameen Gro Skøien Johannessen Marianne Stenrød Girum Tadesse Tessema Marit Almvik Hans Geir EikenAbstract
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Abstract
Erwinia amylovora, the causative agent of fire blight of pome fruits and other rosaceous plants belongs to the group of regulated quarantine pests. The aim of this work was to characterize the populations of E. amylovora in Norway and their geographical distribution. A total of 238 E. amylovora isolates recovered from symptomatic host plants in Norway between 1986 and 2004 were genotyped by means of a short sequence repeat (SSR) marker (ATTACAGA) on plasmid pEa29. The SSR region was amplified and amplicon size determined using fluorescent labelling and rapid, automated capillary gel electrophoresis. All isolates contained the pEa29 plasmid harbouring the investigated marker. In total, ten genotypes were identified, of which two were detected only once. The number of repeats varied from 3 to 13, with 43% of the isolates containing five repeats. Of 17 isolates collected between 1986 and 1991, all but one contained five repeats, whereas more variation was observed in isolates from the period 2000 to 2004. Most of the isolates (80%) originated from Cotoneaster bullatus, hence no relationship between genotype of the isolate and host species that it was isolated from could be detected. This historic data suggests multiple introductions of E. amylovora to Norway.
Abstract
Background The order Lepidoptera has an abundance of species, including both agriculturally beneficial and detrimental insects. Molecular data has been used to investigate the phylogenetic relationships of major subdivisions in Lepidoptera, which has enhanced our understanding of the evolutionary relationships at the family and superfamily levels. However, the phylogenetic placement of many superfamilies and/or families in this order is still unknown. In this study, we determine the systematic status of the family Argyresthiidae within Lepidoptera and explore its phylogenetic affinities and implications for the evolution of the order. We describe the first mitochondrial (mt) genome from a member of Argyresthiidae, the apple fruit moth Argyresthia conjugella. The insect is an important pest on apples in Fennoscandia, as it switches hosts when the main host fails to produce crops. Results The mt genome of A. conjugella contains 16,044 bp and encodes all 37 genes commonly found in insect mt genomes, including 13 protein-coding genes (PCGs), two ribosomal RNAs, 22 transfer RNAs, and a large control region (1101 bp). The nucleotide composition was extremely AT-rich (82%). All detected PCGs (13) began with an ATN codon and terminated with a TAA stop codon, except the start codon in cox1 is ATT. All 22 tRNAs had cloverleaf secondary structures, except trnS1, where one of the dihydrouridine (DHU) arms is missing, reflecting potential differences in gene expression. When compared to the mt genomes of 507 other Lepidoptera representing 18 superfamilies and 42 families, phylogenomic analyses found that A. conjugella had the closest relationship with the Plutellidae family (Yponomeutoidea-super family). We also detected a sister relationship between Yponomeutoidea and the superfamily Tineidae. Conclusions Our results underline the potential importance of mt genomes in comparative genomic analyses of Lepidoptera species and provide valuable evolutionary insight across the tree of Lepidoptera species.
