Phylogenetic position and characteristics of the new group

of Pseudomonas spp. causing bacterial canker on cherry

Pseudomonas syringae is a causal agent of bacterial canker of stone fruit trees. It attacks all organs of the aboveground parts of the trees and it is found in all

fruit trees growing areas in the world. The greatest damage occurs in orchards and nurseries of stone fruit trees, especially in sweet and sour cherries. Necrosis

on the main trunk and branches sometimes lead to the death of entire trees. In young orchards losses causing by this disease can reach even 75%. On sweet and

sour cherry, two pathovars of P. syringae: syringae (Pss) and morsprunorum (including race 1 and 2-Psm1 and Psm2) are known.

The aim of this study was characteristics and determination of the phylogenetic position of atypical group isolates from sour cherry by PCR MP, rep-PCR and MLST.

Repetitive PCR ERIC, BOX, REP and IS50 PCR,

Melting Profile PCR (PCR MP)

Multilocus Sequence Typing

The results of rep-PCR, PCR MP and MLST allowed for distinction of group of sour cherry isolates showing atypical characters in phenotypic tests (similar

to Pss) and in pathogenicity assay (they caused superficial lesions as strains of Psm1 and 2).

This is not describet yet group of isolates was found to be highly homogenic.

Their phylogenetic position, beetween Pss and Psm strains is still not well defined but it suggests that their constitute an intermediate form between

this two taxa.

The further study towards description of the will be conducted.

Fig. 2. Dendrogram showing the genetic

diversity of studied strains of Pss, Pss(A),

Psm1, Psm2 based on data of PCR MP

using UPGMA analysis and Dice’a coefficient.

Fig. 1. Dendrogram showing the genetic diversity

among strains Pss, Pss(A), Psm1, Psm2 obtained from

concatenated data from REP, ERIC, BOX and IS50 PCR

MP using UPGMA analysis and Jaccard’s coefficient.

Fig. 3. Maximum Likelihood tree showing phylogenetic relationship between studied strains of Pss, Pss(A), Psm1, Psm2 based on sequences of genes gapA, gltA, gyrB and rpoD. Bootstrap values (expressed as percentages of 1000

replications) are given at the nodes. Bar – estimated nucleotide substitutions per site.

gapA gltA gyrB rpoD

New pathogenic group

of isolates from sour cherry

New pathogenic group

of isolates from sour cherry

New pathogenic group

of isolates from sour cherry

Monika Kałużna, Joanna Pulawska,

Research Institute of Horticulture, Pomology Division, Pomologiczna 18 str., Skierniewice, Poland

During monitoring conducted in 2007-2011

from 25 of 63 orchards of stone fruit trees

located in different regions of Poland 153

Pseudomonas isolates were obtained.

Based on results of LOPAT, GATTa and

L-lactate tests despite well known stains

of Pss, Psm1 and Psm2, the atypical group

of strains, not producing esculine and

utilizing L-lacate as Pss strains but showing

atypical pathogenic abilities as Psm were

found.

This group of atypical strains, named Pss(A)

was originating from sour cherry.