To Detect Genetically Modified Organism (GMO) Using Oligonucleotide Microarray

With the increasing development of genetically modified organism (GMO) detection techniques, the Polymerase Chain Reaction (PCR) technique has been the mainstay for GMO detection. And an oligonucleotide microarray is a glass chip to the surface of which an array of oligonucleotides was fixed as spots, each containing numerous copies of a sequence-specific probe that is complementary to a gene of interest. So it is used to detected tens or more targets synchronously.In this research, we developed a multiplex polymerase chain reaction (multiplex-PCR) coupled with a DNA microarray system simultaneously aiming at many targets in a consecutive reaction to detect a GMO.We designed two types DNA microarray, one to detect whether the sample was from GMO, the other to detect which event the sample was from.For the first type, there are a total of 20 probes for detecting a GMO in a DNA microarray which can be classified into three categories according to their purpose: the first for screening GMO from un-transgenic plants based on the common elements such as promoter, reporter and terminator genes; the second for specific gene confirmation based on the target gene sequences such as herbicide-resistance or insect-resistance genes; the third for species-specific genes which the sequences are unique for different plant species. To ensure the reliability of this method, different kinds of positive and negative controls were used in DNA microarray. Commercial GM soybean, maize, rapeseed and cotton were identified by means of this method and further confirmed by PCR analysis and sequencing. The results indicate that this method discriminates between the GMOs very quickly and in a cost-saving and more time efficient way. It can detect more than 95ï¼…of currently commercial GMO plants and the limits of detection are 0.5ï¼…for soybean and 1ï¼…for maize.For the second type, an event-specific detection strategy based on the unique and specific integration junction sequences between the host plant genome DNA and the integrated gene is being developed for its high specificity using multiplex-PCR together with oligonucleotide microarray. Commercial GM soybean (GTS 40-3-2), six GM maize events (MON810, MON863, Bt176, Bt11, GA21, and T25) were detected by this method. The results indicate that it is a suitable method for the identification of these GM soybean and maizes.This method is proved to be a new method for routine analysis of GMOs.