DIFFERENTIATION OF ERWINIA AMYLOVORA AND E. PYRIFOLIAE STRAINS WITH SINGLE NUCLEOTIDE POLYMORPHISMS AND BY SYNTHESIS OF DIHYDROPHENYLALANINE

Strains of the species Erwinia amylovora are highly homogeneous among each other.
The Asian pear pathogen Erwinia pyrifoliae is also a quite homogeneous species.
On the nucleotide level, differentiation of individual E. amylovora strains from North America and from other countries was achieved with single nucleotide polymorphisms (SNPs) in the genes gale and in acrB and hrpA. The discriminating PCR primers were specific at the 3’end and were applied at a high annealing temperature during the beginning of the PCR runs.
Discrimination was possible in conventional PCR and in quantitative PCR. E. amylovora strains were further distinguished biochemically by synthesis of L-2,5-dihydrophenylalanine (DHP), an inhibitor of the shikimate pathway of bacteria, fungi and plants.
DHP production was tested by thin layer chromatography and by growth inhibition of the yeast Rhodotorula glutinis. The compound was not produced by the E. amylovora strains isolated outside of North America.
Approximately half of the American strains were positive for DHP. Raspberry strains share the characteristic SNP pattern of the fruit tree strains from North America, but may carry additional changes in gale. The gale gene of E. pyrifoliae differs for strains isolated in Korea and in Japan.
We designed specific PCR primers from the gale gene to distinguish between strains from both countries.
All E. pyrifoliae strains produced DHP.

XII International Workshop on Fire Blight

I. Gehring, K. Geider, T. Rausch

SNPs, fire blight, Asian pear blight, nucleotide sequences

https://doi.org/10.17660/ActaHortic.2011.896.10