Breeding Potatoes for More Calcium

Have you ever cut into a potato to find a dark spot or hollow part? Early research shows that these defects are likely the result of calcium deficiencies in the potato—and that tuber calcium is genetically linked to tuber quality.

Neither consumers at grocery stores nor chip and fry manufacturers want these low-calcium defects. In addition to the obvious cosmetic issues, these potatoes are more likely to rot.

Most farmed varieties of potatoes have naturally low levels of calcium. So researchers at the USDA-ARS and University of Wisconsin-Madison, including Shelley Jansky, John Bamberg and Jiwan Palta, looked to wild potatoes. Their purpose: to breed new potato cultivars with high calcium levels.

Many wild potato relatives are still present in South America. Their presence means growers’ potato plants in that region often exchange genes with wild species.

“That’s a way they continue to evolve as the climate changes or as disease and pest patterns change,” says Jansky. “But in the U.S. we have removed our potatoes from that environment. We have to breed new genes in from these wild relatives when we want to improve our cultivars.”

These wild relatives are an invaluable resource for scientists across the country.

“If you go down there and drive along the roadside you can see these weedy, wild plants growing along the roads and fields,” says Jansky. “Whenever we have looked for any trait in wild potato species, we have been able to find it.”

And so it was with searching for a high-calcium potato. The team found a wild potato with almost seven times as much calcium as typically grown varieties. The next job was to isolate the calcium trait. Jansky and her colleagues interbred the high- and low-calcium potatoes. The resulting generations showed a molecular marker—a pattern in the plant’s natural DNA. This pattern led researchers to the plant’s calcium trait.

“Finding this marker will allow us—and other breeding programs—to make faster progress in breeding potato plants with high tuber calcium content,” says Jansky. “This has been difficult and time-consuming in the past. You have to grow all the populations, harvest tubers, and then analyze the tubers for the trait you are looking at—in this case, tuber calcium levels. And that’s a long, laborious process.”

A typical breeding program grows and assesses up to 100,000 seedlings every year. It takes 10 to 15 years to release a particular variety of crop plant. However, the process simplifies with known molecular markers.

“We can collect DNA from seedlings and check for these molecular markers,” says Yong Suk Chung, the first author of the study. “If you have the marker present, then you select those seedlings and save a tremendous amount of time and labor.”



WPVGA Researcher of the Year

Horticulture professor Jiwan Palta is the recipient of the Wisconsin Potato and Vegetable Growers Association Researcher of the Year Award for 2016.

According to the WPVGA announcement, Palta was nominated for serving “the Wisconsin potato industry for many years with his valuable research focusing on the impact of Jiwan-Palta-20151calcium and nitrogen nutrition on potato tuber quality and yield under heat and drought stress. Working in the areas of molecular biology, crop physiology, and postharvest quality, Palta has been involved in collaborative potato breeding and variety development activities to enhance farm sustainability. His research program recently led an effort to understand the mechanism of action of a natural lipid that acts as a bioregulator to help improve the shelf life of fruits, flowers and vegetables.”

Palta received the award during a banquet at the 2016 UW-Extension & WPVGA Grower Education Conference and Industry Show in Stevens Point in early February.

Commenting on the award, horticulture department chair Irwin Goldman noted Palta’s long track record of successful research and outreach in potato. “Jiwan has developed an in-depth understanding of calcium fertility and nutrition in potato and translated his findings into recommendations that are followed on many acres around Wisconsin and throughout the world. This award signifies the value of his contributions to Wisconsin’s potato and vegetable growers, one of our most important constituents in the state,” says Goldman.

Reposted from ecals newsletter 02.22.2016