Detection and Quantification of Plant Viruses by PCR

The polymerase chain reaction (PCR) is a technique that enables the specific amplification and hence detection of target DNA sequences from complex mixtures of nucleic acid. A combination of short, specific primers and thermostable DNA polymerases are used to amplify the target sequence, through repeated cycles of denaturation, reannealing, and DNA synthesis at high temperatures, allowing an exponential increase in the amount of the DNA of interest. By addition of a reverse-transcription (RT) step, PCR can also be applied to cDNA generated from RNA templates. Its extreme sensitivity and high specificity make it an unparalleled technique for the detection and characterization of rare messages, including viral infections that are difficult to detect and diagnose by serology or electron microscopy.