Download Plant Pathogenic Bacteria

Plant
Pathogenic
Bacteria
Edited by
Solke H. De Boer
Kluwer Academic Publishers
cross-breeding or by genetic engineering (5,8).
Biological control of F. syringae pv tomato has been largely unexpl
Although A brasilense, a well-known plant growth-promoting bacteria (P
is not known as a biocontrol-PGPB, it is known to produce antimicr
agents such as bacteriocins and siderophores. In addition, A brasilens
restrict tiie proliferación of other rhizospnere bacteria including nonpatho
bacteria (7), and pathogens such as P. syringae pv tomato (2), probably b
conipeting with theni. The aim of this study was to determine if se
relatively ineffective pathogen control agents could act synergistically
used in combination to improve control of bacterial leaf speck disea
tomato.
Material and Methods
Organisms, growth conditions, inoculation techniques, and evaluati
disease development and severity are as described elsewhere in this vo
(2).
Bacteriocide, antibiotic, and heat treatment of seeds. Commercial c
bacteriocide (a mixture of 0.5 % copper hydroxide and 0.3% c
oxychloride) and commercial streptomycin sulfate (0.02 %) were applied
aerosol using a commercial garden sprayer. Seeds were inoculated
bacteria after the pesticide spray had dried. For heat treatments, infected
with P. s. pv tomato were incubated in a circulating water bath (42-45 °C
h). Immediately after the excess water had drained, heat-treated seeds
inoculated with bacteria.
296
S.H. De Boer (ed.). Plañí Palhogenic Bacteria, 296-300.
© 2001 Kluwer Academic Publishers. Printed in the Netherlands.
rthwest (CIB), POB 128, La Paz
isease of tomato caused by
} are inefficient (1) because
compounds (4,9) commonly
ugh this disease is usually
lato plants and reduce crop
3ver or in greenhouses (121.
he foliage as dry as possible
,11,12), either by traditional
is been largely unexplored.
-promoting bacteria (PGPB).
i to produce antimicrobial
addition, A brasilense can
ia including nonpathogenic
Somato (2), probably by outras to determine if several
Id act synergistically when
erial leaf speck disease of
hniques, and evaluation of
i elsewhere in this volume
seeds. Commercial copper
iroxide and 0.3% copper
[0.02 %) were applied as an
eds were inoculated with
t treatments, infected seeds
I water bath (42-45 °C for 2
íd, heat-treated seeds were
seeds. Inoculation of tomato seeds with either
tomato foliage with A brasilense, streptomycin
bactericide before or after inoculation with
significant lasting effect on disease severity or
(Table 1).
Table 1. Effect of various disease control ag
development, and height and dry weight of tom
Disease
Disease
development
development
after 15 days
after 6 days
(0-3)
(0-3)
Before inoculation with P. s. pv tomato
Seed inoculation 1.85a A
2.88a B
with A brasilense
2.57aB
Foliar inoculation 1.67a A
with A
brasilense1
2.61aB
Streptomycin
0.12bA
sulfate
2.81aB
Copper
1.77a A
bactericide
2.95a B
Untreated plants
1.91a A
After Inoculation with P. s. pv tomato
2. 92a B
Seed inoculation
2.25a A
with A
brasilense2
2.84a B
Foliar inoculation 2. 35a A
with A brasilense
2.74aB
0.2lbA
Streptomycin
sulfate
Copper
2.43a A
2.88a B
bactericide
2.93aB
Untreated plants
2. 55a A
Treatment
P. s. pv tomato - Pseudomonas syringae pv. tom
1 P. s. pv tomato was applied 30 min after appl
2 A. brasilense was applied immediately after P
3 Numbers in each column, and in each secti
case letter, differ significantly at P<0.05 in AN
(Disease severity) denoted by a different cap
P<0.05 in Student's í-test.
Combined Control Agents
P. s. pv tomato - Pseudomonas syringae pv tomato
Numbers in each column denoted by a different lower case letter di
significantly at P<0.05 in ANOVA or Studenfs f-test.
Treatment of tomato seeds infected with P. syringae pv tomato with
combination of mild heat (42-45 °C), A. brasilense inoculation, and late
single application of a copper bactericide, almost eliminated bacterial
speck disease even when the plants were grown in a mist chamber for 6 we
(Table 3). Plants treated in this manner grew similarly to uninfected pla
(Table 3).
This study demonstrates that a combination of several ineffective dise
control treatments may reduce the development and severity of bacterial
speck disease in tomato.
jy intervals (a third or less of
disease severity in toinato
I significantly slowed disease
ata not shown). Later, after
iber to dry conditions, there
iamage to plant foliage was
;n alone (Table 2).
and dry weight of tomato
se combined with a single
ns at 5-day intervals.
Plant dry weight (g) after 60
days
14.9b
9.8a
16.5b
15.6b
it lower case letter differ
t.
vingae pv tomato with a
? inoculation, and later a
eliminated bacterial leaf
mist chamber for 6 weeks
larly to uninfected plants
several ineffective disease
1 severity of bacterial leaf
seedlings after seed treatment with mild he
single bactericide application.
Treatment
Combined
control
agents
Inoculated P. s. pv
tomato
Noninoculated
Noninoculated and
treated
Disease severity (
after 42 days in m
0.35a
2.84b
None
None
P. s. pv tomato - Pseudomonas syringae pv. to
Numbers in each column denoted by a
significantly at P<0.05 in ANOVA or Studen
Ackn owledments
This study is dedicated to the memory o
Israel. I thank Dr. Ellis Glazier for editing th
Clieryl Patten for styling the text. This s
Nacional de Ciencia y Tecnologia (CONAC
and # 28362-B and by the Bashan Foundatio
Referen ees
1. Bashan, Y. 1997. Alternative strategie
caused by Pseudomonas syrngae. In: Pse
related pathogens. Developments in p
Rudolph, T.J. Burr, J.W. Mansfield, D. st
Kluwer Academic Publishers, Dordrecht,
2. Bashan, Y. 2000. The tomato rhizosp
populations of the plant growth-pro
brasilense than its pathogen Pseudomon
as a strategy to control bacterial leaf spec
3. Bashan, Y., Fallik, E., Okon, Y., and
pimpinellifolium P.I. 126927: a source o
tomato. Hassadeh 62: 533-534. (In Hebre
4. Cooksey, D.A., and Azad, H.R. 1992. A
metáis
of copper-resistant
plantpseudomonads. Appl. Environ. Microbiol
5. Fallik, E., Bashan, Y., Okon, Y., Cah
Inheritance and sources of resistance to
by Pseudomonas syringae pv. tomato. An