Issue |
Agronomie
Volume 10, Number 5, 1990
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Page(s) | 407 - 416 | |
DOI | https://doi.org/10.1051/agro:19900507 |
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. Boutefnouchetba 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