quorum sensing in xanthomonas

Quorum Sensing in Xanthomonas
Narayan Prahlad V
7th Semester
Molecular Biology

Contents
 Introduction
 Quorum sensing
 Xanthomonas
 Quorum sensing in Xanthomonas
 QS pathway
 Quorum sensing-Virulence
 Conclusion
 References

Quorum Sensing
Quorum sensing (QS)-phenomenon-bacteria communicate among each other in a cell density
dependent media to regulate their gene expression by- release of certain molecules.
Signaling molecules-two main chemical categories:
N-acyl homoserine lactones (AHLs)- autoinducer-1 (AI-1)-characteristic of Gram-negative
bacteria;
autoinducing peptides (AIPs)-Gram-positive bacteria.
Chemically different signaling molecules have also been identified-
A-factor from Streptomyces (γ-butyrolactone),
 4-quinolones Pseudomonas Quinolone Signal -PQS
 fatty acids (Diffusible Signal Factors-DSF).

General mechanism of QS
(Steven T. Rutherford1 and Bonnie L.
Bassler-2012)

Xanthomonas
Kingdom -Bacteria
Phylum -Proteobacteria
Class -Gammaproteobacteria
Order -Xanthomonadales
Family -Xanthomonadaceae
Genus -Xanthomonas
Size of Genomic DNA - 4.17 Mbp- 5.12 Mbp
Electron Microscopic image of Xanthomonas

 X. campestris pv campestris, X. citri.
Citrus cankerBacterial leaf spot

Xanthomonas oryzae. pv. oryzae
-Bacterial Blight (BB)
X .oryzae pv oryzicola
bacterial leaf streak (BLS).
Electron Microscopic Image of Xoo
in Xylem vessel of Rice

QS in Xanthomonas
QS takes place by production of- Diffusible Signal Factor (DSF).
The perception of these signals can influence different aspects of bacterial behavior like
biofilm formation, synthesis of virulence factors etc.
(cis-11-methyl-2-dodecenoic acid)

DSF- Diffusible Signal Factor
Synthesised by gene- rpf.
rpfF- DSF Synthase.
Robert P. Ryan and J. Maxwell Dow-2011

Ya-Wen He & Lian-Hui Zhang-2008
QS Pathway-Cell Density

Ya-Wen He & Lian-Hui Zhang-2008

QS Pathway-
Daniela Buttner & Ulla Bonas-2009

Quorum Sensing-Virulence
Degree of infection- Virulence
1) Extracellular polysaccharide (EPS)
2) Biofilm
3) Lipopolysacharide

EPS Biofilm
(Rai et.al 2015)
Gram –ve Cell wall
Xcc Xoo

Effect of Fungal Endophytes-
Xanthomonas oryzae
Sonika Jha-2014 unpublished

List of Endophytes
Fungus Host
A. Alternaria Catheranhus roseus
B. Arthirinium Elaeocarpus serratus
C. Aspergillus Altingea excelsa
D. Bartalinia BT-cotton
E. Botrytis Erythroxylon monogynum
F. Chaetomium BT-cotton
G. Colletrotrichum BT-cotton
H. Corynespora Entada rheedi
I. Curvularia Pedilanthus tithymaloides
J. Cylindrocladium Piper mullesua
K. Dendryphion Coldenia procumbens
L. Drechslera Coldenia procumbens
M. Fusarium Sargassum wightii
N. Gilmaniella Datura metal
O. Humicola Datura metal
P. Lasiodiplodia theobromae Coelogyne sp.(Orchid)
Q. Nigrospora Leucas aspera
R. Penicillium BT-cotton
S. Pestalotiopsis Syzgium cumini
T. Phomopsis NBT-cotton
U. Phylosticta Turpinia nepalensis
V. Pithomyces Eurya nitida
W. Trichocladium Datura metal
X. Trichoderma harzianum Sargassum wightii
Y. Xylaria Zizyphyus jujuba

Technique
Primary culture-Rifampicin, Cyclohexamide (CHM) and Cephalaxin (CPL)
Secondary culture- 0.2% Primary culture
Control- only culture
Methanol control (MC)- culture + methanol
20μl fungal endophytes was added.
Incubated for 44 hours
O.D-600 nm

Effect of Fungal Endophytes-
Xanthomonas campestris
Sonika Jha-2014 unpublished

Effect of Fungal Endophytes- Alternaria
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Xom/C Xom/MC Xom/20μl Xom/25μl Xom/30μl Xcc/C Xcc/MC Xcc/20μl Xcc/25μl Xcc/30μl
O.Dat600nmafter24Hours
Strains
Endophyte from Alternaria (Crude Extract)

Technique
Primary culture of Xoo and Xcc-Rifampicin, Cyclohexamide (CHM) and Cephalaxin (CPL)
Secondary culture- 0.2% Primary culture
Control- only culture
Methanol control (MC)- culture + methanol
20,25 and 30μl endophyte from Alternaria was added to both.
Incubated for 24 hours
O.D-600 nm

Conclusion
 QS plays an important role in bacteria during pathogenesis.
 some marine organisms- Squids.
 The light organ is colonized by a large number of Vibrio fischeri - autoinducer accumulates to a threshold
concentration, triggering light production.
 These examples of cell-cell communication demonstrate what might be called multicellular behavior in
that many individual cells communicate and coordinate their activities to act as a unit.
 Xanthan- used as a food additive-as a food thickening agent (in salad dressings, for example)
stabilizer (in cosmetic products, for example, to prevent ingredients from separating).

References
Daniela Buttner & Ulla Bonas (2009); Regulation and secretion of Xanthomonas virulence factors. FEMS Microbiol Rev 34
(2010); 107- 121.
DAVID O. NIÑO-LIU PAMELA C. RONALD AND ADAM J. BOGDANOVE (2006); Xanthomonas oryzae pathovars: model
pathogens of a model crop. 2006 BLACKWELL PUBLISHING LTD.303-310.
Robert P. Ryan and J. Maxwell Dow (2011); Communication with a growing family: diffusible signal factor (DSF) signaling in
bacteria. Trends in Microbiology March 2011, Vol. 19, No. 3; Cell Press.145-150.
Ya Wen He et.al; Quorum sensing and virulence regulation in Xanthomonas campestris; 2008; Institute of Molecular and Cell
Biology, Singapore, Singapore; FEMS Microbiol Rev; 842-854
Steven T. Rutherford1 and Bonnie L. Bassler (2012); Bacterial Quorum Sensing: Its Role in Virulence
and Possibilities for Its Control Cold Spring Harb Perspect Med 2012;2: a012427. Cold Spring Harbor Laboratory Press. 2012; 1-
3, 9-11
Robert P. Ryan and J. Maxwell Dow (2011); Communication with a growing family: diffusible signal factor (DSF) signaling in
bacteria. Trends in Microbiology March 2011, Vol. 19, No. 3; Cell Press.145-150.
Christopher M.Waters and Bonnie L. Bassler (2005). Quorum Sensing: Cell-to-Cell Communication in Bacteria; Annu. Rev.
Cell Dev. Biol. 2005.

Acknowledgements
I would like to thank my guide R. Chandrakanth for his guidance.
I would also like to thank our course coordinator Dr. N.S Devaki for providing
me this opportunity to present this seminar.
I would whole heartedly thank the members in the lab of Plant-Microbe
Interaction, CDFD, Hyderabad.
Thank u all for your patience.

Type II and III Secretion Systems
6 types of Secretion systems (SS). Type I (T1S)- VI (T6S).
Vary in composition and function.
Not conserved.
T2S and T3S are very important during host-pathogen interaction.

Daniela Buttner & Ulla Bonas-2009T2S and T3S Systems

Control
Cultural Methods-
At the nursery stage-
seed disinfection, proper nursery drainage, and removal of diseased plants, weeds
and debris.
Prior to transplanting, fields-disinfected by burning rice straw left from the
previous season.
Weeds-removed from canals and ridges in order to reduce natural habitats for
the pathogen and its dispersal through irrigation water.
Paddy field stage, judicious fertilization and proper plant spacing are the most
recommended cultural methods of control.

Chemical Methods-
Bordeaux mixture (hydrated lime and copper sulfate) , several antibiotics,
mercuric and copper compounds.
Inefficent- damage rice grains when sprayed.
In temperate regions, probenazole-added to the paddy water before and after
transplanting the seedlings-to inhibit bacterial multiplication and prevent or retard
the disease.
Other chemicals such as tecloftalam, phenazine oxide and nickel
dimethyldithiocarbamate are sprayed directly on plants
However, chemical control of BB in the tropical monsoon climate of Asia is
impractical, and no truly effective bactericide is commercially available for disease
control.

Biological control-
Pseudomonas fluorescens and P. putida strain V14i (also used in biocontrol
of the rice sheath blight pathogen Rhizoctonia solani) significantly suppressed
BB severity when sprayed on leaves.
Breeding and deployment of resistant cultivars carrying major resistance (R )
genes-most effective approach to controlling BB.

quorum sensing in xanthomonas

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