Knowing Your Roots

Blog 4

When you think about how to use new advances in X-ray technology, potato breeding is probably not the first thing that springs to mind. However, scientific researchers at the University of Wisconsin are doing just that to help develop new potato varieties — and to do it faster!  State-of-the art, high- speed X-ray technology is now becoming a routine practice for evaluating potential new potato varieties, because it is faster and much more effective.  Do you remember your last X-ray at the doctor office? It was time-consuming, uncomfortable and expensive.  Not so with potatoes! Every day during harvest, tens of thousands of potatoes are examined in just milliseconds, at virtually no cost!

This technology is possible by incorporating a high speed X-ray imager into the potato-grading line (where potatoes are evaluated after harvest).  This imager takes an X-ray image of each tuber as it passes through the machine at a high rate of speed.  From that image,  computers calculate just about anything that you ever wanted to know about that tuber, including its weight, length, width, height and shape; most remarkably, it can determine if there are defects on the outside and even the inside of the tuber. This is a huge improvement on previous technology in both speed and expense, which is akin to doctors being able to take the X-rays they need as you drive past the clinic!  

But why would potato breeders need this level of sophistication?  Will it contribute to developing a better spud that can be stored at lower temperatures to avoid sprouting and breakdown, resist disease or tolerate drought? The answer is a resounding yes!  In the complex and protracted science of developing new varieties, many thousands of crosses (plant breeding that deliberately interbreeds desirable properties) must be whittled down to a select few that possess the characteristics that will satisfy the needs of consumers.  By improving the speed and accuracy of the grading process, we are now able to identify potential varieties quicker and more efficiently than ever before.

In my research, I am seeking to pinpoint the location of specific genes that allow a potato to be stored at low temperatures. This is a highly desirable trait as tubers that are stored below typical refrigerator temperatures accumulate sugars. This is unacceptable to consumers and food processors alike since the tubers taste overly sweet and also turn dark brown when made into chips or French fries.  However, if we could store potatoes at lower temperatures and avoid these problems, then we could extend the availability of high quality tubers to provide a year-round supply and avoid the equally unacceptable results of higher temperature storage — the nasty wrinkling, sprouting and rotting that we have all seen in our pantries.  To find spuds that have the traits that allow them to be stored at lower temperatures, I have crossed potatoes with varying responses to temperature and created a series of unique lines for which I am developing DNA profiles.  With these, I can identify where the desired genes are located that will allow researchers to speed up the development of potential new varieties.

High-speed X-ray imaging may seem overly technical for a mere potato, but it is now an essential step to evaluate multiple tuber characteristics of these new lines rapidly and accurately. This helps me to determine if the lines that carry the cold storage gene will be acceptable as new varieties — to the processors that make the chips and fries and to the consumers that enjoy them.

For more information contact Kyle Rak at: krak@wisc.edu. Kyle is the 2014-15 recipient of the Wisconsin Distinguished Graduate Fellowship awarded annually by the Wisconsin Potato Industry Board.

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