Bacteria associated with hazelnut (Corylus avellana L.) decline are of two groups: Pseudomonas avellanae and strains resembling P. syringae pv. syringae.
A total of 118 fluorescent pseudomonads associated with hazelnut decline, which has been occurring for many years in different areas of northern Greece and Italy, were assessed by performing a repetitive PCR analysis with enterobacterial repetitive intergenic consensus, box element, and repetive extragenic palindromic primer sets, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell protein extracts, a carbon compound utilization analysis, and an analysis to determine the presence of the syrB gene. A subset of 53 strains was also characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA) by using nine restriction endonucleases. The virulence of 40 representative strains was assessed by using serial doses. The pathogenic specificities of the strains were also verified. ARDRA carried out with HinfI revealed two main groups of strains, groups A and B, which exhibited a level of similarity of 57%. The other eight restriction endonucleases used did not separate the strains. In addition, a cluster analysis performed by the unweighted pair group method using arithmetic averages after repetitive PCR and SDS-PAGE of protein extracts also revealed the same two groups. Furthermore, the differential utilization of some carbon compounds made it possible to differentiate the groups. Virulence assessment clearly indicated that the group A strains are very virulent, whereas the group B strains proved to be mildly virulent for hazelnut. Group A included the strains isolated in northern Greece and central Italy (i.e., the province of Viterbo); these strains do not have the syrB gene, are pathogenically restricted to Corylus avellana, and belong to Pseudomonas avellanae. Group B includes the other strains obtained from hazelnut cultivated in Piedmont, Campania, Latium, Sicily, and Sardinia. They represent a distinct taxon closely related to Pseudomonas syringae pv. syringae.
Scortichini
Marco
M
Istituto Sperimentale per la Frutticoltura, Via di Fioranello, 52 I-00040 Ciampino Aeroporto, Rome, Italy. mscortichini@hotmail.com
Marchesi
Ugo
U
Rossi
Maria Pia
MP
Di Prospero
Paola
P
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D015373:Bacterial Typing Techniques; D029401:Betulaceae / Q000382:microbiology*; D016172:DNA Fingerprinting / Q000379:methods; D006115:Greece; D007558:Italy; D009754:Nuts; D010453:Peptide Synthases; D010935:Plant Diseases / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D011549:Pseudomonas / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity; D015183:Restriction Mapping; D014197:Trees / Q000382:microbiology*; D014774:Virulence
D001426:Bacterial Proteins; D010453:Peptide Synthases; C094581:SYRB1 protein, Pseudomonas syringae