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