A genome-wide analysis of desferrioxamine mediated iron uptake in Erwinia spp. reveals genes exclusive of the Rosaceae infecting strains

Ivan Polsinelli,Luigimaria Borruso,Rosanna Caliandro,Alfonso Esposito,Luca Triboli,Stefano Benini

doi:10.1038/s41598-019-39787-x

Ivan Polsinelli, Luigimaria Borruso + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-39787-x

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Abstract

Erwinia amylovora is the etiological agent of fire blight, a devastating disease which is a global threat to commercial apple and pear production. The Erwinia genus includes a wide range of different species belonging to plant pathogens, epiphytes and even opportunistic human pathogens. The aim of the present study is to understand, within the Erwinia genus, the genetic differences between phytopathogenic strains and those strains not reported to be phytopathogenic. The genes related to the hydroxamate siderophores iron uptake have been considered due to their potential druggability. In E. amylovora siderophore-mediated iron acquisition plays a relevant role in the progression of Fire blight. Here we analyzed the taxonomic relations within Erwinia genus and the relevance of the genes related to the siderophore-mediated iron uptake pathway. The results of this study highlight the presence of a well-defined sub-group of Rosaceae infecting species taxonomically and genetically related with a high number of conserved core genes. The analysis of the complete ferrioxamine transport system has led to the identification of two genes exclusively present in the Rosaceae infecting strains.

Highlights

Fire blight is one of the major threat to Rosaceae with a potentially disastrous economic impact on apple and pear production[1]
The Average Nucleotide Identity (ANI) values and the phylogenetic analysis consistently highlighted a clear division between the Rosaceae infecting pathogens (RIP) and the other species (Non Rosaceae infecting pathogens, NRIP)
All phylogenetic analysis (Figs 1 and 2b) suggest a different evolutionary rate within the RIP. These difference can be appreciated by looking at the branch length in Fig. 1b: the distance between E. amylovora, E. pyrifoliae, Erwinia sp Ejp[617], E. piriflorinigrans and E. tasmaniensis is shorter than any distances among other species

Summary

Introduction

Fire blight is one of the major threat to Rosaceae with a potentially disastrous economic impact on apple and pear production[1]. Not all Erwinia species are able to synthetize their own siderophores, suggesting that iron uptake is a potential niche adaptation factor[12]. In E. amylovora, siderophore mediated iron uptake is dependent on desferrioxamines (DFOs)[14]: molecules consisting of alternating diamine and dicarboxylic acid building blocks www.nature.com/scientificreports/. The lack of specific hydrolases in E. amylovora and the incompatibility of the cytoplasmic pH with the proton-assisted dissociation suggests that the iron is released after its reduction (ferrioxiamine has a lower affinity for Fe(II) than for Fe(III)), as in E. coli[24]. Average Nucleotide Identity (ANI), phylogenetic inference based on conserved marker genes, pangenomic analysis and molecular diversity analysis have been performed to get insights about the relevance of siderophore mediated iron acquisition in the evolution of pathogens’ hosts selectivity and virulence

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