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Sanger Sequencing

The science behind better varieties

At Elsoms, our R&D team are continually working on and developing newer, better varieties for our growers across the world. Sanger sequencing is one of many techniques we use to gain a competitive edge in the marketplace. Below, our Genomics Specialist, Eleri Tudor, explains the process of Sanger Sequencing, and how we continually develop stronger varieties, year on year.

DNA sequencing

DNA is a molecule that carries the information, or genetic code, that determines how an organism will look and function. It is made of pairs of building blocks called nucleotides abbreviated as a single letter A (adenine), G (guanine), C (cytosine) and T (thymine). We can imagine a DNA molecule like a long string of these four letters.

DNA sequencing technologies are used to determine the exact order of the four nucleotides A, G, C and T. The first method of DNA sequencing was developed by Frederick Sanger in 1977 and we still use this method to detect DNA markers that are associated with a trait of interest.

Example of Sanger sequencing chromatograph
Shown here is example data generated by Sanger sequencing technology. The genetic sequence highlighted on the top and the output chromatogram below.

DNA markers are differences in DNA sequences between individuals that are associated with a trait of interest.

2 examples of Sanger sequencing side by side for comparison.

If we compare Variety A with Variety B, there is a difference in their DNA sequence, highlighted in red.

In the example above this difference in DNA sequence determines whether a variety is resistant or susceptible to disease and can be used as a DNA marker. By looking for this DNA marker, we can detect if our new breeding material shares the same trait for  disease resistance.

We can test hundreds of individuals to find those that are resistant and exclude those that are susceptible.

Multiple sanger sequencing tests besides one another showing varying degrees of susceptibility to a disease in the results


In the past, to confirm that an individual was resistant to this disease we would grow the material in the field or lab and visually assess for signs of disease resistance. This can be very time consuming and expensive. Using DNA markers cuts down the breeding time significantly and enables Elsoms to bring newer and better varieties to the market much quicker.