HOST-PARASITE INTERACTION REVEALS INTER- AND

INTRASPECIFIC VARIATION FOR PHELIPANCHE SPECIES

A G R I C U L T U R A L U N I V E R S I T Y O F A T H E N S

Lyra1, D., Economou1, G. and Kotoula-Syka2, E.1. Agricultural University of Athens Hellas

2. Democritus University of Thrace Orestiada Hellas

E-mail: dionyssialyra@yahoo.com

2nd International Conference on «Novel and Sustainable Weed Management in arid and semi-arid agro-ecosystems» 7-10 September Santorini Hellas

Introduction Material & Methods Results Discussion & Conclusions

Theory

building

O. minor

O. cumana Ph. aegyptiaca

Ph. ramosa O. crenata

(Gianniantonio Domina 2005)

Broomrapes as holoparasites

depend on their host-plants for resources

in order to secure their survival and perpetuation

Introduction Material & Methods Results Discussion & Conclusions

Theory

building

Orobanche and Phelipanche species

A varying degree of host-plant specificity

Introduction Material & Methods Results Discussion & Conclusions

O. minor Ph. aegyptiaca

Ph. ramosa

O. cumana O. crenata

What is host specificity?

Introduction Material & Methods Results Discussion & Conclusions

Introduction Material & Methods Results Discussion & Conclusions

HOST SPECIFICITY

O O

O O

O

CH3

CH3 CH3

H

OCH3 CH3 O

O O

O

CH3

OH

H

OCH3 CH3 O

O O

O

CH3

H

OH

Stimulan

ts

Seeds

5-DeoxystrigolOrobanchol

2‘-epi-Orobanchol

Hosts

Broomrapes

Root system

During host-parasite interaction,

A VARIATION

has been observed from both sides which has to do with………

Introduction Material & Methods Results Discussion & Conclusions

HOST SPECIFICITY

Introduction Material & Methods Results Discussion & Conclusions

Hosts

Broomrape

species

1st case

…stimulantsSolanaceae

Cannabidaceae

Compositae

Cruciferae

Cucurbitaceae

HOST SPECIFICITY

Introduction Material & Methods Results Discussion & Conclusions

Host

Broomrape

populations

Pop. 1

Pop. 2

Pop. 3

Pop. 4

2nd case… variable response

Introduction Material & Methods Results Discussion & Conclusions

HOST SPECIFICITY

Hosts

BroomrapesBroomrape seeds

demonstrate different sensitivity in the biochemical stimulus derived from plant-host

roots

Not all host plants do they exude

substances with the same chemical

composition

The main research objective

of our study

Introduction Material & Methods Results Discussion & Conclusions

Why are we interested in studying population diversity?

Populations are categorized according to the level of divergence between them

Variability (morphological, genetical, physiological, spatial heterogeneity)

Hybrids / Subspecies (Ph. ramosa / Ph. aegyptiaca)Races (O. cumana)

Host-specificity is one of the driver of genetic divergence

Impact on decision-making processes for Orobanche control

Broomrape plants were collected from naturally parasitized tobacco and

tomato crops

Sampling

Introduction Material & Methods Results Discussion & Conclusions

2002-2004

Ph. aegyptiaca

Ph. ramosa / Ph. aegyptiaca

Ph. ramosa

Introduction Material & Methods Results Discussion & Conclusions

Tobacco

Ph. ramosa

Results Discussion & ConclusionsIntroduction Material & Methods

Tomato

Results Discussion & ConclusionsIntroduction Material & Methods

20 Phelipanche ramosa populations28 Phelipanche aegyptiaca populations

Results Discussion & ConclusionsIntroduction Material & Methods

1st experiment• Hosts: 2 rapeseed varieties (EXACT, CALIFORNIA) -

tobacco3 Phelipanche ramosa populations4 Phelipanche aegyptiaca populations

2nd experiment• Host: tobacco13 Phelipanche ramosa populations6 Phelipanche aegyptiaca populations

3rd experiment• Host: tomato18 Phelipanche ramosa populations9 Phelipanche aegyptiaca populations

Results Discussion & ConclusionsIntroduction Material & Methods

Plastic bag assays were used to study hosts and holoparasite interactions

in vivo

MEASUREMENTS• Germinated

seeds

• Formed tubercles

Results Discussion & ConclusionsIntroduction Material & Methods

Statistical analysis* Data did not follow Normal Distribution

* Kruskal – Wallis test / Nemenyi test

* Box-Whisker plot

?

A E G

R A M

0 4 8 1 2 1 6 2 0 2 4

Mean

MedianOutliers

Interquartile range

Data range

1st experimentC a n o l a – To b a c c o

Results Discussion & ConclusionsIntroduction Material & Methods

CALIFORNIA EXACT TOBACCO0

20

40

60

80

100

CALIFORNIA EXACT TOBACCO0

20

40

60

80

100

CALIFORNIA EXACT TOBACCO0

4

8

12

16

20

24

a

b

b

CALIFORNIA EXACT TOBACCO0

1

2

3

4

5

a a

b

Formed tuberclesGermination (%)

Ph. ramosaPh. ramosa

Ph. aegyptiaca

Ph. aegyptiaca

a a

b

b

a

c

Interspecific variability

LA1 LA2 LA3 LA4 LA5 LA6 LA70

20

40

60

80

100O. ramosa O. aegyptiaca

LA1 LA2 LA3 LA4 LA5 LA6 LA70

6

12

18

24

30

36

LA1 LA2 LA3 LA4 LA5 LA6 LA70

20

40

60

80

100

LA1 LA2 LA3 LA4 LA5 LA6 LA70

3

6

9

12

15

LA1 LA2 LA3 LA4 LA5 LA6 LA70

20

40

60

80

100

LA1 LA2 LA3 LA4 LA5 LA6 LA70

2

4

6

8

CALIFORNIA EXACT TOBACCO

Form

ed tu

berc

les

Ger

min

atio

n (%

)

Intraspecific variability

c

d d

ab ab a

bc

O. ramosa

O. aegyptiaca

bc a

c a a

d

ab

O. ramosa O. aegyptiaca

a b

e

a

c

d

f

a a

d

a

b c

eO. ramosa O. aegyptiaca

c

a c

a

d

b

eO. ramosa O. aegyptiaca

a a a

a

c

a

b

O. ramosa O. aegyptiaca

B r o o m r a p e p o p u l a t I o n s

B r o o m r a p e p o p u l a t I o n s

B r o o m r a p e p o p u l a t I o n s

B r o o m r a p e p o p u l a t I o n s

B r o o m r a p e p o p u l a t I o n s

B r o o m r a p e p o p u l a t I o n s

(Phelipanche populations collected on tobacco same region-same year)

• Ph. ramosa‘s seeds germinated more by tobacco

• More host-specific

• Ph. aegyptiaca’s seeds germinated more by canola

• Less host-specific • Less tubercles on canola root system• More tubercles on tobacco root system

results

2nd experimentTobacco

Results Discussion & ConclusionsIntroduction Material & Methods

?

AEG

RAM

0 20 40 60 80 100

b

Ph. aegyptiaca

Ph. ramosa

Germination (%)

?

AEG

RAM

0 3 6 9 12 15

a

a

Ph. aegyptiaca

Ph. ramosa

Formed tubercles

a

Interspecific

Variability

? A1A2A3A4A5RARBRCRDRERFRGRHRI RJRKRLRM0

20

40

60

80

100O. ramosaO. aegyptiaca

?1 A 1 A 2 A 3 A 4 A 5 R A R B R C R D R E R F R G R H R I R J R K R L R M

0

3

6

9

12

15 O. ramosaO. aegyptiaca

For

med

tube

rcle

sG

erm

inat

ion

(%)

Phelipanche populations

Intraspecific

variability

Ph. ramosa populations collected on

tobacco different regions-

different years

Region 1 Collection year 2002

Region 2

2004Region

12003

Region 1 Collection year 2002

Region 22004

Region 1

2003

Region 22004

Region 22004

results

• Ph. ramosa‘s seeds germinated more compared to Ph. aegyptiaca’s seeds

• The number of tubercles was not statistical different for both species

• High variability among and within regions • High variability among and within collective

years

3rd experimentTomato

Results Discussion & ConclusionsIntroduction Material & Methods

?

AEG

RAM

0 20 40 60 80 100

Ph. aegyptiaca

Ph. ramosa

b

Germination (%)

?

AEG

RAM

0 4 8 12 16 20 24

b

Ph. aegyptiaca

Ph. ramosa

Formed tubercles

a

a

Interspecific

Variability

? 1? 2? 3? 4A1A2A3A4A5A6A7A8A9RARBRCRDRERFRGRHRIRJRKRLRMRNRORPRQRR0

20

40

60

80

100

O. ramosaO. aegyptiaca

? 1? 2? 3? 4A1A2A3A4A5A6A7A8A9RARBRCRDRERFRGRHRIRJRKRLRMRNRORPRQRR0

4

8

12

16

20

24 O. ramosaO. aegyptiaca

Phelipanche populations

For

med

tube

rcle

sG

erm

inat

ion

(%)

Intraspecific

variability

Ph. ramosa populations collected on

tobacco different regions-

different years

Region 3 Collection year 2002

Region 4

2004

Region 2

2004

Region 3Collection year 2002

Region 42004Region

22004

Region 12004

Region 12004

Region 32003

Region 32003

results

• Ph. ramosa‘s seeds germinated more compared to Ph. aegyptiaca’s seeds

• The number of tubercles was statistical different for both species

• High variability among and within regions • High variability among and within collective

years

• Ph. ramosa seems to be more host-specific

Results Discussion & ConclusionsIntroduction Material & Methods

• Tobacco – a traditional crop• Canola – a newly introduced cultivation

Why were not many tubercles formed on canola root system by Ph. ramosa (1st experiment)?

Why were not many tubercles formed on tobacco root system by Ph. ramosa, although germination was high (1st

experiment)? • Tobacco variety

• Second level of resistance

Are Ph. aegyptiaca/Ph. ramosa highly host-specified species ? No

Results Discussion & ConclusionsIntroduction Material & Methods

Massive collections of seeds

Where can population variability be attributed?

WeightShapeSizeSeed coat

Physiological age

Dormancy

Genetic material

Results Discussion & ConclusionsIntroduction Material & Methods

Spatial heterogeneity

Climate

Landscape Topography

Soil