Detailed Description of DArT™ Technology

Note: This technology is available for use to anyone that agrees to the improvement-sharing conditions of a royalty-free BiOS Genetic Resources Indexing Technology License.

In order to detect genetic differences between several cultivars of a crop species the first step in the DArT technique is to extract DNA from the plants of interest.A portion of DNA from each cultivar is mixed and the long strands of DNA within the mixture are then cut into smaller fragments using a selection of enzymes that target specific regions along the length of the DNA. The result is a pool of DNA sections of varying sizes, which are then processed through several steps to produce multiple copies of the smaller fragments. This is called a 'representation' and it has a reduced complexity as compared with the original genetic material. Eventually, these fragments are placed as tiny spots onto a batch of identical glass slides using a microarrayer machine.

To determine the genetic differences between any two cultivars of a plant, the second part of the technique involves preparing a 'representation' from each cultivar as before, labelling the DNA with a fluorescent dye and then binding the labelled DNA onto two of the microarrayed glass slides. At this stage, the labelled DNA samples bind only to matching DNA spots on the glass slides, resulting in a signal that can be read and measured by a scanner machine. The result for each cultivar will be different, depending on which spots the DNA binds to, and these differences show the degree of diversity between the two cultivars.

Finally, the slides are scanned for signals generated from each DNA spot and these are converted into binary scores of 0's and 1's. The data is compiled, analysed and managed using the world-class DArTsoft and DArTdb computer package, which was developed and refined in-house to process the large amount of data generated by the technique.

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