1998 WWLPT Biology Institute:  Motion 

What Turns Seeds On?


Protocol for Recipes and Serial Dilutions

To prepare 40 8-cm diameter petri dishes containing a 1% bacto-agar / 2% soluble starch solution:
It is important to use sterile techniques whenever working with agar plates.  The reason for this is to prevent contamination from microorganisms.

  1. Wash the working area with water.
  2. Wipe down the area with 95% ethanol solution.  Allow the alcohol to evaporate.  This is important as a heat source will be used.
  3. Add 500 mL distilled water to a 600 mL beaker containing 5 g bacto-agar and 10 g soluble starch.
  4. Use a heat source (microwave / bunsen burner / hot plate) to dissolve all components.

    5. ** Watch this carefully as the solution has a tendency to overflow.  DO NOT BOIL!
  5. Let the solution cool to about 57oF.
  6. Pour about 20 mL bacto-agar quickly into sterile petri dishes (to prevent solidification).
  7. Let solidify.  If these dishes will be used within 24 hours, store inverted at room temperature.  If not, refrigerate.
To prepare abscisic acid solution:
* This is enough for ten lab groups.
Normal physiological levels of abscisic acid in plants are on the order of 10-6 M.
Note:  The molar mass of abscisic acid is 264 g.
  1. Mass 0.0264 g of abscisic acid powder.

    2. Note:  Abscisic acid must be stored below 0oC and is light sensitive.
  2. Transfer the abscisic acid to a 100 mL volumetric flask.
  3. Add less than 2 mL of 95% ethanol to help dissolve the abscisic acid in water.
  4. Once the abscisic acid is dissolved, add enough distilled water to create a 100 mL ABA solution.

    5. This makes a 10-3 M abscisic acid solution.
  5. Transfer 1 mL of the ABA solution with a sterile disposable pipette to a 1 L volumetric flask.  Add 999 mL of distilled water to create a 10-6 M ABA solution.
To prepare gibberellic acid solution:
* This is enough for ten lab groups.
Normal physiological levels of gibberellic acid in plants are on the order of 10-6 M.
Note:  The molar mass of gibberellic acid is 346 g.
  1. Mass 0.0346 g of gibberellic acid powder.
  2. Transfer the gibberellic acid to a 100 mL volumetric flask.
  3. Add less than 2 mL of 95% ethanol to help dissolve the gibberellic acid in water.
  4. Once the gibberellic acid is dissolved, add enough distilled water to create a 100 mL GA3 solution.

    5. This makes a 10-3 M gibberellic acid solution.
  5. Transfer 1 mL of the GA3 solution with a sterile disposable pipette to a 1 L volumetric flask.  Add 999 mL of distilled water to create a 10-6 M GA3 solution.
To disinfect the corn seeds:
  1. After the seeds have soaked for 24 hours, place them into a beaker with 25 mL of Clorox for 1-2 minutes.
  2. Rinse the seeds several times with distilled water until the Clorox odor is gone.
 

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