Quorum Sensing

2.2 Detection and
Measurement of DSF

1. The DSF biosensor strainXanthomonas campestrispv.campes-
   tris8523.


2. Strains to be tested for DSF production.


3. Glass tubes containing 3 ml LB broth supplemented with the
   appropriate antibiotic(s).


4. Erlenmeyer flasks (250 ml) containing 50 ml LB broth.


5. Sterile pipette tips or toothpicks.


6. Temperature-controlled shaker.


7. Spectrophotometer.


8. Autoclaved Whatman paper discs (10 mm diameter).


9. Fluorescent binocular microscope.


10. Plastic loops (2 mm diameter).


11. 1.5 ml tubes.


12. 96-well black microtiter plate.


13. Fluorescence microplate reader.

2.3 Pathogenicity
and Colonization Tests

1. Young plants (3-week-old) ofPelargonium x hortorumgrow-
   ing in individual pots (seeNote 2).


2. Pots filled with a mixture of 2/3 peat and 1/3 Tuff (crushed
   volcanic rocks).


3. Bacterial suspension of strains to be tested at a concentration of
   108 cells/ml.


4. Disposable needles, size 21 G.


5. Sterile plastic (low density polyethylene) bags
   (0.16 cm0.1 cm).


6. Hammer and crusher for plant maceration.


7. Pipettes and sterile tips (5–50, 40–200μl).


8. Sterile scissor.


9. Sterile 1.5 ml tubes.


10. Sterile water.


11. LB agar plates.


12. Incubator.


13. Greenhouse for maintaining the plants with temperature of
    25–28C and drip irrigation.

2.4 Confocal
Microscopy

1.Xhp(or other plant pathogenic strains) labeled with GFP (see

Note 3).

2. Confocal laser scanning microscope.


3. YoungPelargoniumplants growing in pots.


4. Syringe-driven membrane filters 0.22μm.

Quorum Sensing-Dependent Virulence of Phytopathogens 245