Pulverize 100 mg of plant sample using a liquid nitrogen chilled mortar and pestle. Once processed, mix 100 mg of frozen powdered sample with 500 µl of CTAB Plant Extraction Buffer.
Place the homogenate into a 60°C bath for 30 min.
Centrifuge the homogenate for 10 minutes at 10,000 x g.
Transfer the supernatant into a clean tube and add 5 µl of RNase (10 mg/ml in water) to the lysate. Incubate at room temperature for 15 minutes.
Centrifuge for 5 minutes at 10,000 x g.
Extract the lysate with equal volume of chloroform: isoamyl alcohol (24:1). Vortex for 5 seconds then centrifuge for a minute at 10,000 x g to separate the phases.
Transfer the upper phase to a clean tube.
Repeat step 7 until upper layer is clear. Transfer upper phase to a new tube.
Add 0.7 volumes of isopropanol. Mix and incubate at -20°C for 15 minutes.
Centrifuge for 10 minutes at 10,000 x g. Decant and wash the pellet with 70% ethanol.
Decant without disturbing the pellet. Dry the pellet briefly in the SpeedVac (3 minutes at medium heat). Do not over dry the DNA.