Molecular analyses of Erwinia amylovora strains isolated in Russia, Poland, Slovenia and Austria describing further spread of fire blight in Europe

Abstract

Fire blight, a bacteriosis of apple and pear, was assayed with molecular tools to associate its origin in Russia, Slovenia and south-eastern Austria with neighboring countries. The identification of all investigated strains was confirmed by MALDI-TOF mass spectroscopy except one. Independent isolation was verified by the level of amylovoran synthesis and by the number of short sequence DNA repeats in plasmid pEA29. DNA of gently lysed E. amylovora strains from Russia, Slovenia, Austria, Hungary, Italy, Spain, Croatia, Poland, Central Europe and Iran was treated with restriction enzymes XbaI and SpeI to create typical banding patterns for PFGE analysis. The pattern Pt2 indicated that most Russian E. amylovora strains were related to strains from Turkey and Iran. Strains from Slovenia exhibited patterns Pt3 and Pt2, both present in the neighboring countries. Strains were also probed for the recently described plasmid pEI70 detected in Pt1 strains from Poland and in Pt3 strains from other countries. The distribution of pattern Pt3 suggests distribution of fire blight from Belgium and the Netherlands to Central Spain and Northern Italy and then north to Carinthia. The PFGE patterns indicate that trade of plants may have introduced fire blight into southern parts of Europe proceeded by sequential spread.

Phylogeography and population structure of the biologically invasive phytopathogen Erwinia amylovora inferred using minisatellites

“…Since we failed to identify isolation by distance within Europe, we hypothesize multiple introduction events causing this split population. These population differences were previously unidentifiable in similar studies, although some population structure has been elucidated before (Jock et al ., 2002; 2013; Donat et al ., ). While the MLVA analysis showed a strong evidence for two populations within Europe, this finding has yet to be confirmed by other methods such as high‐throughput SNP typing or next generation sequencing.…”

Contrasting genetic variation and positive selection followed the divergence of NBS-encoding genes in Asian and European pears

“…These results also suggest that P. communis and P. bretschneideri, endured different disease pressures during their divergence and domestication. For example, fire blight and brown spot damage was reported in pear production in Europe and west Asia [4][5][6][7][8][9][10], while ring rot, bitter rot, and scab infections occurred in China and east Asia [11][12][13][14]. The co-evolution with local pathogen populations and distinct disease pressure on pear production in different geographical areas can explain the difference in selection patterns across NBS-encoding genes in Asia and Europe.…”

“…The wild populations of these two pear groups have likely experienced unique disease pressures due to their completely different habitats. For example, brown spot (caused by fungus Stemphylium vesicarium) and fire blight (caused by bacteria Erwinia amylovora) diseases lead to death of pear trees and threaten the pear industry in Europe and west Asia [4][5][6][7][8][9][10]. Black spot (caused by fungus A. alternata), scab (caused by fungus Venturia nashicola), ring rot (caused by fungus Botryosphaeria berengeriana), and bitter rot (caused by bacteria Colletotrichum fructicola) diseases, in turn, cause huge losses to pear production in China and east Asia [11][12][13][14].…”

Using Molecular Tools To Decipher the Complex World of Plant Resistance Inducers: An Apple Case Study

“…Furthermore, the obvious long-term breeding programs for resistance do not allow quick response to spatiotemporally limited attacks . All of these specificities explain why fire blight is still expanding around the world with regular outbreaks and why it has been classified as a quarantine disease in most countries. The use of PRIs to confer protection against E. amylovora is an attractive strategy to prevent or reduce incidence of fire blight to an acceptable level.…”