Genomic DNA was purified from 50 mg samples of fresh leaf tissue from cotton and wheat using the BioSprint 15 DNA Plant Kit and BioSprint 15 DNA Plant protocol. DNA was eluted in 200 µl Buffer AE. Amplification (20 µl reaction volume) was carried out using the trnL PCR system (amplifying an intergenic region of a tRNA coding gene in the chloroplast genome) with 5 µl, 0.5 µl, or 0.05 µl purified DNA from 4 cotton samples and 3 wheat samples. PCR products were visualized on a 0.8% agarose gel. M: markers (1 kb ladder).