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Increasing problems with Erwinia’s -the ecology of blackleg pathogens
Outline
The pathogenBlackleg situation in EuropeEcology: introduction and disseminationControl
Wilting symptoms
Basal stem rot (blackleg)
Browning of vascular system, maceration of pith tissue
Tuber symptoms
Stolon end infectionsInfections on wounded tubers
Browning of vascular and parachymatic tissue
Blackleg causal organisms
E. chrysanthemi Dickeya paradisiaca, D. dianthicola, D. chrysanthemi, D. zeae, D. dieffenbachia, D. dadantii
E. carotovora subsp. atroseptica Pectobacteriumatrosepticum
Erwinia carotovora subsp. carotovoraPectobacterium carotovorum subsp. carotovorum
E. c. subsp. brasiliensis (South America+South Africa) Pectobacterium carotovorum subsp. brasiliensis
Survey Erwinia in blackleg-diseased plants (NL)
No
Source: NAK
Declassified + rejected seed lots in the Netherlands
Source: NAK
0
5
10
15
20
25
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Year
% d
ecla
ssifi
ed
• 63 fields• 91 plants• 27 varieties
2004• 59 fields• 117 plants• 30 varieties
2003• 49 fields• 79 plants• 27 varieties
- EAPR Meeting , Hämeenlinna ; 2-6 July 2007
Survey Erwinia in blackleg-diseased plants (Fr) 2005
UMR 1099Biologie des Organismes et des Populations
appliquée à la Protection des Plantes (Bio3P)
Research program funded by potato growers and fresh potato industry :
Source : V. Hélias
0
20
40
60
80
2003 2004 2005
PcaDckPccNo
fiel
ds %
Is the increase due to global warming?
http://www.cru.uea.ac.uk
Growth temperature characteristics Erwinia’s
Growth temperature(in oC)
E. carotovorasubsp. carotovora
E. c. subsp. atroseptica
E. chrysanthemi
Minimum 6 3 6
Optimum 28-30 27 34-37
Maximum 37-42 35 ≥ 37
Revised after Pérombelon & Kelman, 1980
Temperature versus Ech infections
0
5
10
15
20
25
2001 2003 2005 Normal
Year
oC
April
May
JuneJuly
August
High average temperatures in June associated with Dickeya infections
Recent potato strains
(Biovar 3):
- Israel
- Poland
- Finland
- The Netherlands
DnaX-sequence analysis European potato strains ≤ 1995
Pectinolysis at 37 oC for Dickeya species
Janse & Ruissen, 1988
Introduction Erwinia’s during seed multiplication
Cultivar 1st generation 2nd generation
Nr. seedlots
Eca(E-ELISA)
Ech(E-PCR)
Nr. seedlots
Eca(E-ELISA)
Ech(E-PCR)
Desiree 13 0 0 13 1 1
Kondor 23 0 0 20 2 2
Spunta 17 1 0 18 3 4
5x10 tubers/seed lot were analysed
0
2
4
6
8
10
12
1-yr 2-yrs 3-yrs 4-yrsgenerations
% d
egra
datio
n Clonal selection,no compositeClonal selection,compositeIn vitro
Source: NAK/NAK-Agro
Field generations versus % degradation in 2006
0102030405060708090
100
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% d
isea
sed
plan
ts
C4, sympt field C4, Sympt labC4, Elisa Ech
0102030405060708090
100
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% d
isea
sed
plan
ts
A4, sympt field A4, sympt labA4, Elisa Eca
0102030405060708090
100
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% d
isea
sed
plan
ts
A7, sympt field A7, sympt labA7, Elisa Eca
Low densities of Ech can give blackleg
high, 107
cells/ml
Ech Eca
low, 104
cells/ml
0102030405060708090
100
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% d
isea
sed
plan
ts
C7, sympt field C7, sympt labC7, Elisa Ech
low, 104
cells/ml
high, 107
cells/ml
0102 03 04 05 06 07 08 09 0
10 0
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% p
lant
s
Symptoms ELISA
0102030405060708090
100
3-jun
10-jun
17-jun
24-jun
1-jul
8-jul
15-jul
22-jul
% p
lant
s
Symptoms ELISA
0102030405060708090
100
9-ju
n
16-ju
n
23-ju
n
30-ju
n
7-ju
l
14-ju
l
21-ju
l
% p
lant
s
Symptoms ELISA
0102030405060708090
100
9-ju
n
16-ju
n
23-ju
n
30-ju
n
7-ju
l
14-ju
l
21-ju
l
% p
lant
s
Symptoms ELISA
2005, low 2006, low
2005, high 2006, high
Low densities of Ech can give blackleg
012345678
0 1 7 23 42 84
dagen
log
cfu/
g
Ecc1990Eca1987Ech2019Ech1991Ech980
Bron: J.M. van der Wolf, J. van Doorn
Erwinia cannot overwinter in soil ...
... even not in crop debris
110
1001000
10000100000
100000010000000
1000000001000000000
M H M H
Dickeya Ecc
log
cfu+
1/g
plan
t mat
eria
l
0 days36 days64 days112 days
Stem fragments were still present at day 112
Soil M = peaty soil, Soil H = sandy soil
Erwinia survive for less than two days on materials
012345678
0 3 6 24 30 48
uren
log
cfu/
ml
EccEchEca
hours
PVC
0
20
40
60
80
100
Control Treated plants Neighbouring plants Plants adjacent row
% E
ch p
ositi
ve p
lant
s
Erwinia can disseminate in soil
six weeks after treating plants
Can root infections result in an infected progeny?
??
Colonization of plants after soil infestation
Soil of 12 plants was inoculated 2 weeks after planting when stolons were formedPots were dipped in trays containing GFP-tagged Dickeya solani suspensions and left for 40 min Populations dynamics in roots, seed potato, stolons, progeny tubers and stems were analysed 1, 15 and 30 d.p.i.
Can stem infections result in an infected progeny?
??
Distribution after stem inoculation: set up
10 plants were inoculated 2 weeks after planting when stolons were formedSuspensions, of Dickeya sp., were injected into stems, always 3 stems per plant For decreasing the risk of cross contamination of soil inoculation point and soil were covered with plastic foil, plant were watered from the bottom
Symptom developmentSymptom development
plant Symptoms inside stems Blackleg symptoms1 no symptoms no symptoms2 browning typical blackleg3 browning no symptoms4 browning no symptoms5 browning typical blackleg6 browning typical blackleg7 no symptoms no symptoms8 browning typical blackleg, plant decomposed
9 browning no symptoms10 browning no symptoms
4 water control plants were negative
Stem infections can result in an infected progeny!
Inoculation point: 100%
Stem base: 100%
Roots (upper): 90%
Roots (intermediate): 60%
Roots (down): 30%
Progeny tubers: 70%/15%Stolons: 60%
A strip with rotten Erwinia-tubers was harvested, thereafter tubers from Erwinia-free plantsContamination levels of tubers were analysed at different distances from the contaminated strip using enrichment-PCR Harvesting procedures
ControlTwo-phase system, hand harvesting of lifted tubersTwo-phase system, harvesting of lifted tubers with a machinePotato harvester with axial roller setPotato harvester with a sieve band
Spread of contamination during harvest
Variation highNo significant differences between machines
0
2
4
6
8
10
12
14
Control two-phase, hand Machines
Ave
rage
sm
earin
g (m
)
Avoid spread of contamination via machines
Rainfall harvest time versus blackleg incidence
020406080
100120140160180
2000 2001 2002 2003 2004 2005 Normal
year
Rai
nfal
l (m
m)
JulyAugust
0
5
10
15
20
25
2000 2001 2002 2003 2004 2005 2006
Year
% d
ecla
ssifi
ed
Rainfall
Declassification
Concluding remarks
Blackleg incidences fluctuate largely, but last years more problems are foundIncidences of last three-years are more connected to Dickeya infectionsDickeya’s can induce symptoms at low densitiesDickeya is not a better survivorAvoid spread of contamination during harvest to control Erwinia’s
Contributors
HZPC ResearchHenk Velvis
FNPPPT/INRA-RennesValérie Helias
NAKGé van de BovenkampEisse de Haan
Plant Research InternationalPatricia van der ZouwenRobert CzajkowskiJan van der Wolf