Characterization of Pseudomonas savastanoi pv. Savastanoi Strains Collected from Olive Trees in Different Countries
To investigate the variability of a Pseudomonas savastanoi pv. savastanoi population, 53 isolates of the bacterium, isolated in Albania, Italy, Morocco, Portugal and Turkey from knots of several olive cultivars, were characterized at molecular levels by rep-PCR and f-AFLP. All bacterial strains were pathogenic on olive plants and produced fluorescent pigments on King’s B medium. They were negative for levan, oxidase, arginine dihydrolase and potato soft rot and induced hypersensitive reaction in tobacco plants. Based on these results and on the amplicon generation of the iaaL and the ptz genes by PCR, all the isolates can be considered belonging to P. savastanoi pv. savastanoi. Rep-PCR analysis, performed using ERIC primers and the novel primers KRP2-KRP8 and KRPN2, demonstrated that fingerprints obtained with the novel primers were more polymorphic with respect to those generated with ERIC primers. UPMGA, performed combining data from the 3 primer sets, revealed 26 distinct fingerprints with an overall similarity of about 82%. Most of the isolates from Morocco and Umbria (Italy) as well as the pathovar reference strain of P. savastanoi pv. savastanoi are grouped in a cluster. In addition, all Turkish and Albanian isolates and most of the isolates from Apulia (Italy) form another cluster. F-AFLP analysis provided a significantly higher resolution than the rep-PCR and revealed high polymorphisms between the isolates. It has the potential to play a major role in characterizing P. savastanoi pv. savastanoi populations. Virulence tests were performed on the olive cv. Frantoio with 19 bacterial isolates, selected on the basis of rep-PCR fingerprints. Wide virulence variability among the isolates was found. Knot volume significantly correlates with knot weight, allowing the evaluation of disease progress in a non-destructive manner. Sequencing of genetic traits of the bacterium likely involved in its pathogenicity and virulence is in progress.
KeywordsOlive Pseudomonas savastanoi pv. savastanoi rep-PCR f-AFLP virulence
Unable to display preview. Download preview PDF.
- Rademaker J. L. W., De Bruijn F. J. (1997). Characterization and classification of microbes by rep-PCR genomic fingerprinting and computer-assisted pattern analysis. In: Caetano-Anolles G. and Gressfoff P. (eds.). Protocols, application and overviews, pp. 151–171. Wiley, New York.Google Scholar
- Schaad N. W., Jones J. B., Chun W. (2001). Initial identification of common genera. In: Schaad N. W., Jones J. B. and Chun W. (eds.). Laboratory guide for identification of plant pathogenic bacteria, pp. 84–120. Third edition. APS, St. Paul, MN.Google Scholar
- Schroth M. N., Hildebrand D. C., O’Reilly H. J. (1968). Off-flavor of olives from trees with olive knot tumors. Phytopathology 58: 524–525.Google Scholar
- Schroth M. N., Osgood J. W., Miller T. D. (1973). Quantitative assessment of the effect of the olive knot disease on olive yield and quality. Phytopathology 63: 1064–1065.Google Scholar
- Sisto A., Cipriani M. G., Cerboneschi M., Santilli E., Stea G., Tegli S. (2006). Characterisation of Pseudomonas savastanoi pv. savastanoi strains isolated from different host plants by f-AFLP. 13° Congresso Nazionale S.I.Pa.V., Foggia, Italy, 12–15 September 2006. Book of abstracts, p. 43.Google Scholar