# Phenotypic analysis and numerical taxonomy of Pseudomonas syringae pv. syringae isolated from commercial pear orchards of Spain

E. Montesinos, L. Gardan, C. Bollet, C. Manceau

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E. Montesinos, L. Gardan, C. Bollet, C. Manceau. Phenotypic analysis and numerical taxonomy of Pseudomonas syringae pv. syringae isolated from commercial pear orchards of Spain. 4th International Working Group on Pseudomonas syringae Pathovars', Università degli Studi di Firenze [Firenze]. ITA., Jun 1991, Firenze, Italy. pp.439. hal-01601940

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PHENOTYPIC ANALYSIS AND NUMERICAL TAXONOMY OF
Pseudomonas syringae pv. syringae ISOLATED FROM
COMMERCIAL PEAR ORCHARDS OF SPAIN

Montesinos, E.¹, Gardan, L.², Bollet, C.³, and Manceau, C.²

1. Dept. Crop Sciences, Polytechnic University of Catalunya and Agricultural Experiment Station "Mas Badia", 17003 Girona (Spain)

2. INRA-Station de Pathologie Végétale et Phytobacteriologie 49070 Angers (France)

3. Hôpital Salvator, 249 bd Ste-Marguerite, 13009, Marseille (France)

Blast of dormant flower buds is a disease of economic importance in pear growing areas of Catalunya (Spain). The disease is mainly due to outbreaks of *Pseudomonas syringae* pv. *syringae*, but other non-pathological factors have an influence on severity. The phenotypic variability of 58 strains of *Pseudomonas syringae*, isolated from commercial pear orchards of epidemic areas, was studied. Isolates were selected with the objective of covering a wide range of representative situations including different organs, cultivar types, climatic conditions, fruit growing areas, orchards and seasons. A total of 167 biochemical characters, ice nucleation activity, toxin production and pathogenicity on immature pear fruits and detached leaves were determined for each strain. Results were interpreted by means of numerical taxonomy based on the Jaccard and Sneath coefficient and doing cluster analysis by the UPGMA method. Comparisons were done with data available for *Pseudomonas syringae* pv. *syringae* isolated from other hosts. In spite of the wide variability in origin, up to 80% of the Spanish strains formed a relatively compact cluster which was clearly different from the other clusters of pv. *syringae* isolated from bean, cherry laurel and French pear and from the other pathovars of *Pseudomonas syringae*.