# Difference between multiplication of P.S. pv. Syringae strains, on pear an bean leaves in growth chamber

S. Yessad, Charles Manceau, Jacques Luisetti

► To cite this version:

S. Yessad, Charles Manceau, Jacques Luisetti. Difference between multiplication of P.S. pv. Syringae strains, on pear an bean leaves in growth chamber. 4th International Working Group on Pseudomonas syringae Pathovars, Università degli Studi di Firenze [Firenze]. ITA., Jun 1991, Firenze, Italy. 439 p. hal-01604962

HAL Id: hal-01604962

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Submitted on 4 Jun 2020

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<figure><img src="image_1.png" /></figure>
DIFFERENCE BETWEEN MULTIPLICATION OF P.S.pv.
SYRINGAE STRAINS, ON PEAR AND BEAN LEAVES IN
GROWTH CHAMBER

YESSAD, S., MANCEAU, C. and LUISETTI. J.

Station de Pathologie végétale, INRA, Route de Saint Clément, 49000 Angers, France

The fitness of bacterial adhesion of two strains
of Pseudomonas syringae pv. syringae (P.s.s.)
and one strain of Erwinia herbicola (E.h.) were
monitored on bean leaves by washing the leaves
by a gently spray of sterile distilled water, a
vigorous washing in water for 1hr 30 and shaking
them consecutively. P.s.s. strains attached on
leaves within two days. At the opposite E.h.
strain could be removed from the leaves surface
by gently spraying of water. Washing by vigorous
shaking allowed removal of all bacteria attached
and non attached on leaves during the experi-
ment. This technique was used to monitor the
epiphytic multiplication of four bacterial
strains showing difference in pathogenicity on
pear and bean leaves. Of the two strains of
P.s.s. isolated from pear, only one was pathoge-
nic. Another strain of P.s.s. isolated from bean
was non pathogenic on pear but pathogenic on
bean. Finally, a strain of E.h. which was not
epiphytic and not pathogenic was also used as
control. Under 70% relative humidity, all P.s.s.
strains maintained their populations at the opt-
imum and the populations of E.h. strain decre-
ased slowly on bean leaves, but on pear leaves
only the strain pathogenic on this host was re-
covered 7 days after inoculation. Under 100%
relative humidity on pear leaves, populations of
all strains of P.s.s. grew up to 5x10⁵ cfu/ml,
at the opposite, E.h. populations decreased down
to 5x10² cfu/ml. We conclude that epiphytic
fitness of P.s.s. depends on the plant species
they colonize. On pear leaves pathogenicity of
P.s.s. could be a major factor for bacterial
survival on leaves under dry conditions.