Free access
Issue
Agronomie
Volume 10, Number 5, 1990
Page(s) 407 - 416
DOI http://dx.doi.org/10.1051/agro:19900507
Agronomie 10 (1990) 407-416
DOI: 10.1051/agro:19900507

Variabilité phénotypique de Pseudomonas syringae pv syringae provenant de laurier palme et d'hôtes variés

L. Gardana, S. Cottina, C. Bolletb, G. Hunaultc and N. Boutefnouchetb

a  INRA, station de pathologie végétale et phytobactériologie, 49070 Beaucouzé
b  Hôpital Salvator, 249 bd Ste-Marguerite, 13009 Marseille
c  Faculté des sciences, bd Lavoisier, 49045 Angers, France

Résumé - La criblure bactérienne du laurier palme (Prunus laurocerasus L) a été observée pour la 1re fois en France en 1976; elle est due à Pseudomonas syringae pv syringae. La variabilité phénotypique de 50 souches de P s pv syringae isolées de laurier palme et de 58 souches de P s pv syringae isolées d'hôtes variés a été étudiée. Les résultats ont fait l'objet d'une taxonomie numérique. Les souches de laurier palme, étudiées seules, montrent une certaine variabilité puisqu'elles se répartissent en 6 groupes que l'on peut différencier par 15 caractères biochimiques. Comparées aux autres souches de P s pv syringae, elles se répartissent en 7 groupes caractérisés par 26 caractères biochimiques. Trois souches mal identifiées ne sont pas des P s pv syringae (U 21-1, 1787, 1701). La souche type de P s pv syringae a une distance relativement élevée par rapport à la majorité des autres souches.


Abstract - Phenotypic heterogeneity of Pseudomonas syringae pv syringae isolated from cherry laurel and various hosts. Bacterial leaf spot of cherry laurel (Prunus laurocerasus L) due to P s pv syringae was observed first in 1976 in France. The phenotypic variability was investigated in 50 representative strains of P s pv syringae isolated from cherry laurel and 58 strains of P s pv syringae isolated from 1950 to 1986 from various host-plants classified in 31 genera (tables I and II). The results of 167 biochemical characters were interpreted in numerical taxonomy by the Jaccard and Sneath coefficient. Strains were clustered using the UPGMA method. Strains of P s pv syringae isolated from cherry laurel, analyzed separately, were variable since they were classed in 6 groups (plus 10 isolated phenotypes) that were differentiated by 15 chemical characters (table III and fig 1). Compared with the 58 strains of P s pv syringae, the strains were distributed among 7 groups (plus 10 isolated phenotypes) which are differentiated by 26 biochemical characters (table V and fig 2). Strains of cherry laurel were clustered in 2 groups with other strains of various host-plants (group 2: 5 strains from cherry laurel plus 1 strain from Phaseolus sp and group 6: 44 strains from cherry laurel and 25 strains from various host-plants). The type strain of P s pv syringae was very far from the other strains and not a good type strain. A new strain would therefore have to be chosen. Strains clustered in group 6 could be considered as belonging to species P s pv syringae. However, this would have to be confirmed by DNA/DNA hybridization. The validity of species P s pv syringae and the notion of pathovar are discussed.


Key words: cherry laurel / Pseudomonas syringae pv syringae / variability / numerical taxonomy / identification / biotyping

Mots clés : laurier palme / Pseudomonas syringae pv syringae / variabilité / taxonomie numérique / identification / biotypage