1. collect piece of tissue (e.g., pieces of a leaf or flower) in Eppendorf tube containing 40 ml 0.25 N NaOH

2. put in boiling H₂O for 30 sec (optimum may need to be determined for each type of tissue, for floral tissue 30 sec is fine)

3. neutralize by adding 40 ml 0.25 N HCl and 20 ml 0.5 M Tris-HCl pH 8.0, 0.25% (v/v) Igepal CA-630

4. boil for another 2 min

5. use directly for PCR or store at 4°C for up to several weeks

6. if stored at 4°C boil again for 2 min before the PCR

Remarks:

We don't have too much experience with this method. Mostly it seems to work though. However, I don't think it is safe enough for critical purposes (e.g., mapping).