Evolutionary Ecology of Plant Diseases - A Phylogenetic perspective

1. EVOLUTIONARY ECOLOGY OF PLANT DISEASES :
A PHYLOGENETIC PERSPECTIVE
MASTER’S SEMINAR MPP591(1+0)
Presented by
P.R. Aswinkumar
17412MPP007
Source:-doi10.1111j.1365-2745.2010.01738.x

2. CONTENTS
1. INTRODUCTION.
2. IMPORTANCE OF CONTEXT FOR
PHYLOGENETIC SIGNAL.
3. PHYLOGENETIC SIGNALS IN THE
TRAITS OF PLANTS & MICROBES.
4. PHYLOGENETIC ECOLOGY &
DISEASE.
5. EVOLUTION OF VIRULENCE IN PLANT
PATHOGENS.
6. APPLIED PHYLOGENETIC
PHYTOPATHOLOGY.
7. CASE STUDIES.
8. CONCLUSION.
9. FUTURE ISSUES.
10. REFERENCES

3. PURPOSE
Traits of plants and microbes are shaped by the evolutionary histories.
Host range and disease severity show clear phylogenetic signals.
Pathogen spread and disease impact are influenced by the phylogenetic structures
of host assemblages.
 To develop predictive tools for phytosanitary risk analysis and reduce the
disease pressure in multispecies cropping system.

4. TERMINOLOGY
Ecology:- Branch of biology dealing with the interactions among the organisms and their
environment.
Evolution:-Gradual change in the heritable characteristics of biological populations over
successive generations.
Phylogeny:-Study of evolutionary history and relationships among individuals or group of
organisms.
Phylogenetic signal:- Statistical pattern in which similarity of traits between taxa is related to
their phylogenetic relatedness.

5. INTRODUCTION
Trait conservatism influences many processes in plant pathology and disease ecology.
Things to be dealt in this seminar are:-
A) importance of phylogenetic concepts and tools in understanding the plant diseases.
B) importance of plant pathology in field of phylogenetic ecology.
C) to identify the key challenges for phylogenetic plant disease ecology development.

6. PHYLOGENETIC SIGNAL ASSOCIATED WITH SIMULATED BINARY
AND CONTINUOUS TRAITS ON A PHYLOGENETIC TREE

7. THE IMPORTANCE OF CONTEXT FOR PHYLOGENETIC
SIGNAL
Source :- Gregory S. Gilbert and Ingrid M. Parker ( 2013 )
Angiosperms
Poales Other species of angiosperms
NBS-
LRR
protein
s

8. Phylogenetic signals in the traits of Plants and Microbes
Source :- Gregory S. Gilbert and Ingrid M. Parker (
2013 )

9. PHYLOGENETIC ECOLOGY & DISEASE
Source :- Gregory S. Gilbert and Ingrid M. Parker (

10. LIMITING SIMILARITY IN PLANT PATHOGENS
| https://doi.org/10.3389/fpls.2017.01806Source:- https://doi.org/10.3389/fpls.2017.01806
TLP-2
strain of
P.syringae &
Pathogenic
P.syringae for
Carbon
A.Radiobact
er
(Agromycin-
84) &
A.Tumefacie
ns
F.oxysporum
strains c-14
and c-15
against
pathogenic
F.oxysporum

11. EVOLUTION OF VIRULENCE IN PLANT PATHOGENS
Front. Plant Sci., 25 October 2017 | https://doi.org/10.3389/fpls.2017.01806

13. APPLIED PHYLOGENIC PHYTOPATHOLOGY
1. Phytosanitary risk assessment:- phytosanitary standards established by international
plant protection convention of united nations food and agriculture organisation.
Prioritization requires not only the assessment of impact of pathogens on known host,
but also predicting the potential set of susceptable hosts, if introduced to new area .
 Phylosuscept software of beta version to detect related susceptable species to the
concerned pathogen(under development).

14. 2.Design of managed plant communities:- cropping systems should be designed
such a way that no two crops in sequence should be susceptable to same
pathogen.
 Eg:- Crop rotation of cereals with Pulses.
3. Biological control of pathogens:- fungi also show limiting similarity , which
helps in biocontrol of plant diseases.
Eg:- Supression of pathogenic Pseudomonas syringae pv. tomato(Bacterial
speck of tomato) by P.syringae strain TLP2 (similarity in source of carbon).

15. Case
Study:-1

16. Savoury et al. eLife 2017;6:e30925. DOI:

17. The att, fasR, and fas loci are necessary for the pathogenicity of
Rhodococcus.
Source:-https://doi.org/10.7554/eLife.30925.009

18. Plasmid pFiD188 with functional fasR and fas is
sufficient to transition Rhodococcus isolates to
phytopathogens.
Source:-https://doi.org/10.7554/eLife.30925.016

19. Savoury et al. eLife 2017;6:e30925. DOI: https://doi.org/10.7554/eLife.30925

20. Savoury et al. eLife 2017;6:e30925. DOI:

21. Case study:-2Case study:-2

22. Source:-https://doi.org/10.1073/pnas.1609366113
W=same location
B = different location
S = same host
D = Different host

23. RELATED EXPLANATIONS:-
Selection of pathogen strain for avirulence on host species.
Mating and recombination in pathogen population occurs only on primary host followed
by 10-15 asexual cycles on secondary host promoting the host specificity.
Gene for gene model with relation to coevolution of both host and pathogen.

24. Model of evolutionary changes in pathogen and
host specificities leading to high host specificity in
the pathogen. α and β represent genotypes of
two pathogen elicitors. A and B represent
genotypes of R genes in a given host.
If the subscript of α matches the subscript of A, or
if the subscript of β matches the subscript of B, then
the pathogen is virulent (plant is susceptible).
A–F represent successive evolutionary changes.
The specific changes are indicated by red
subscripts. Pathogen genotypes in red indicate
genotypes introduced to the community either
by immigration or mutation.
Pathogen genotypes directly above host
genotype are virulent on that host.
A α0 β0
A0B0
α0β0
A0B0
α 0β0
A0B0
B
A1B0
αoβ0
A0B0 A0B1
C α1β0
A1B0
α0β0
A0B0 A0B1
D α 1β0
A1B0
α0β0
A2B0 A0B1
E α1β0
A1B0 A2B0
α0β1
A0B1
F α1β0
A1B2
α2β0
A2B0
α0β1
A0B1
Host 1 2 3

25. Conclusion
1.Not all the traits shows Phylogenetic
signals.
3.HGT and Convergent Evolution disrupts
the Phylogenetic signal.
2.Complex traits are conserved at deeper
Phylogenetic levels.
4.Phylogenetic structure of local
communities should be studied incase of
Pathogen Spillover.
5. Phylogenetic tools and concepts helps in answering the
questions of
Plant Pathology and Disease Ecology.

26. Future issues
1.Use of improved metrics for
Phylogenetic signal detection.
2.Study the impact of specialist
and generalist enemies in plant
community.
3.Limiting similarity concept
should be better exploited for
plant disease control.
4.Qualitative measures of
phylogenetic signal are yet to be
applied
5.To study the whole network of phylogenetic structure of plant -
pathogen interactions.

27. REFERENCES
 Gunter Brader, Stephane C, Kathryn V, Birgit M, Friederike T, Li-jun ma, and Angela Sessitsch 2017. Ecology and
genomic insights into plant-pathogenic and plant-nonpathogenic endophytes. Annu. Rev. Phytopathol. 2017.
55:61–83,(https://doi.Org/10.1146/annurev-phyto-080516-035641).
 Gilbert GS, Parker IM. 2016. The evolutionary ecology of plant diseases : A phylogenetic perspective. Annu. Rev.
Phytopathol. 2016. 54:23.1-23.30.
 Gilbert GS. 2002. Evolutionary ecology of plant diseases in natural ecosystems. Annu. Rev. Phytopathol. 2002.
40:13.-43.
 Laine, A.-L., Burdon, J. J., Dodds, P. N., & Thrall, P. H. (2010). Spatial variation in disease resistance: from
molecules to metapopulations. Journal of ecology, 99(1), 96–112. Doi:10.1111/j.1365-2745.2010.01738.
 Parker IM, Saunders M, Bontrager M, Weitz AP, Hendricks R et al. 2015. Phylogenetic structure and host
abundance drive disease pressure in communities. Nature 520:542-44.

28.  R. P. Scheffer 1991. Role of toxins in evolution and ecology of plant pathogenic fungi.Experientia 47 (1991),
reviews birkh/iuser verlag CH-4010 basel/switzerland.
 Savory EA, Fuller SL, Weisberg AI, Thomas WJ, Gordon MI, Stevens DM, Creason AI, Belcher MS, Serdani M,
Wiseman M, Grünwald NI, Putnam ML, Chang IH. 2017. Evolutionary transitions between beneficial and
phytopathogenic rhodococcus challenge disease management. Elife 6:e30925. Doi: 10.7554/elife.30925.
 Selin C, de Kievit TR, Belmonte MF and Fernando WGD (2016). Elucidating the role of effectors in plant-fungal
interactions: progress and challenges. Front. Microbiol. 7:600. Doi: 10.3389/fmicb.2016.00600.
 Thomas M. Chappell, Mark D. Rausher.2016. Evolution of host range in a plant pathogen.Proceedings of the
national academy of sciences may 2016, 113 (19) 5346-5351; DOI: 10.1073/pnas.1522997113.