Use of quantitative PCR to evaluate several methods for extracting DNA from corn flour and cornstarch

Quantitative PCR of a single copy endogenous gene was examined as a tool for evaluating and comparing methods for the extraction of DNA. Relative levels of ivr1 (invertase) were used to evaluate the quality of template DNAs recovered from two corn matrices, corn flour and cornstarch, by several extraction methods. The Wizard method gave the highest yield of DNA from corn flour. Although amplification of the Wizard extracts was inhibited more than that of the extracts obtained with the Nucleospin, Qiagen, CTAB, or Kingfisher methods, the effect of the inhibition was overcome by the relatively high template copy number recovered in the Wizard extracts. The Wizard method was also the most efficacious for the extraction of DNA from cornstarch, however further up-scaling is required to facilitate testing for novel or recombinant sequences.