DNA Fingerprinting: Identification of Organisms Using the Polymerase Chain Reaction and Various Primers

Abstract

The study undertaken involved small scale DNA isolation from eight different fruits using a modified technique written for leaf material. Genetic analysis of this extracted DNA was performed by PCR. Four primers known to target specific DNA sequences were utilized: Analu, Bactoribo, HHFl, and Mitocox. PCR with the Analu, HHFl, and Mitocox primers resulted in a unique pattern of bands that enabled each fruit to be differentiated. Since one major band was observed with the Bactoribo primers and the size of that amplified DNA fragment was either the same or very similar for each fruit, they could not be distinguished based on this primer. Furthermore, the amplification products yielded by the fruits were different from the positive control thus allowing them to be distinguished also. In most cases, 10 ?l of fruit DNA extract in the PCR resulted in the best banding pattern, although informative bands were detected with 1 and 5 ?l of DNA also. Interestingly, 5 ?l of fruit DNA extract in the PCR reaction yielded variable results whereby in some cases, such as with the analu primers, either fewer bands were seen compared to 1 and 10 ?l of DNA, or no bands were visible at all, thus providing less meaningful data. Like RFLP and RAPD analysis, this study demonstrated that the entire genome does not have to be sequenced to detect DNA polymorphisms between different organisms.