[show abstract][hide abstract] ABSTRACT: The plant pathogen Erwinia amylovora can be divided into two host-specific groupings; strains infecting a broad range of hosts within the Rosaceae subfamily Spiraeoideae (e.g., Malus, Pyrus, Crataegus, Sorbus) and strains infecting Rubus (raspberries and blackberries). Comparative genomic analysis of 12 strains representing distinct populations (e.g., geographic, temporal, host origin) of E. amylovora was used to describe the pan-genome of this major pathogen. The pan-genome contains 5751 coding sequences and is highly conserved relative to other phytopathogenic bacteria comprising on average 89% conserved, core genes. The chromosomes of Spiraeoideae-infecting strains were highly homogeneous, while greater genetic diversity was observed between Spiraeoideae- and Rubus-infecting strains (and among individual Rubus-infecting strains), the majority of which was attributed to variable genomic islands. Based on genomic distance scores and phylogenetic analysis, the Rubus-infecting strain ATCC BAA-2158 was genetically more closely related to the Spiraeoideae-infecting strains of E. amylovora than it was to the other Rubus-infecting strains. Analysis of the accessory genomes of Spiraeoideae- and Rubus-infecting strains has identified putative host-specific determinants including variation in the effector protein HopX1(Ea) and a putative secondary metabolite pathway only present in Rubus-infecting strains.
PLoS ONE 01/2013; 8(2):e55644. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Hrp pathogenicity island (hrpPAI) of Erwinia amylovora not only encodes a type III secretion system (T3SS) and other genes required for pathogenesis on host plants, but also includes the so-called island transfer (IT) region, a region that originates from an integrative conjugative element (ICE). Comparative genomic analysis of the IT regions of two Spiraeoideae- and three Rubus-infecting strains revealed that the regions in Spiraeoideae-infecting strains were syntenic and highly conserved in length and genetic information, but that the IT regions of the Rubus-infecting strains varied in gene content and length, showing a mosaic structure. None of the ICEs in E. amylovora strains were complete, as conserved ICE genes and the left border were missing, probably due to reductive genome evolution. Comparison of the hrpPAI region of E. amylovora strains to syntenic regions from other Erwinia spp. indicates that the hrpPAI and the IT regions are the result of several insertion and deletion events that have occurred within the ICE. It also suggests that the T3SS was present in a common ancestor of the pathoadapted Erwinia spp. and that insertion and deletion events in the IT region occurred during speciation.
[show abstract][hide abstract] ABSTRACT: An evaluation of seven published conventional PCR protocols used for the detection of Erwinia amylovora has shown that six out of the seven protocols tested were not specific for all strains of E. amylovora. A collection of 40 genetically diverse strains of E. amylovora and 55 geographically diverse bacteria that are closely related or share the same ecological niche as E. amylovora were used to test the seven PCR protocols. All bacteria were tested for virulence by inoculation of immature pear fruit and
for cultural characteristics on selective media. Only one PCR protocol, Taylor et al. (2001), was specific for all strains of E. amylovora and was able to differentiate E. amylovora from all other bacteria tested. Diagnostic laboratories may need to review their testing procedures in light of these findings.
KeywordsFire blight-Diagnostics-Molecular identification
[show abstract][hide abstract] ABSTRACT: Here, we present the genome of a strain of Erwinia amylovora, the fire blight pathogen, with pathogenicity restricted to Rubus spp. Comparative genomics of ATCC BAA-2158 with E. amylovora strains from non-Rubus hosts identified significant genetic differences but support the inclusion of this strain within the species E. amylovora.
Journal of bacteriology 02/2011; 193(3):785-6. · 3.94 Impact Factor