​Breeding peas for a warmer world
12/09/2017
With the world only getting hotter, scientists are already looking at clever ways of changing up food production to make sure future generations don't go hungry. So far, this has included possibly engineering new types of heat-resistant cattle, using big data to guide crop production and now, breeding new kinds of peas that are built to take the heat. 

According to the American Society of Agronomy, farmers around the globe produce between 10 and 13 million tons of field peas each year, placing it behind only dry beans and chickpeas as a legume crop. But warming temperatures are making things difficult for this household staple.

"In some years, the older varieties of pea weren't growing very well because of heat stress," says Rosalind Bueckert, a plant scientist at the University of Saskatchewan. "We wanted to find new varieties that have robust and consistent yields in a warming world."

Bueckert led a team of researchers in an effort to pinpoint traits in peas that affect heat stress, and in turn learn more about the genes that give them these capabilities. To do this, the researchers cross-bred two commonly used varieties of pea, CDC Centennial and CDC Sage. They then studied more than a hundred new varieties of offspring, some of which would actually demonstrate better heat tolerance than either of their parents.

"By crossing two different varieties of pea, you may be able to breed offspring with traits beyond those of either parent," says Bueckert.

The team then raised some of these new varieties across two growing seasons in Saskatchewan. One batch was seeded at the typical time in mid-May, while a second batch was seeded in June. This meant the second batch flowered later in the year when temperatures were higher, allowing the team to look out for varieties that offered better yields in higher temperatures.

Through this exercise, the team was able to identify two traits in particular that were important for heat resistance in peas: flowering duration and pod numbers. Meaning, that pea varieties with more pods to begin with, and that flower over longer periods, had the best chance to recover from extreme weather events and provide a higher yield.

While visible traits like pod numbers and flowering duration can offer researchers a useful guide when selecting crop varieties, understanding the genes behind those traits could aid them even further. And the team will now seek to do this by identifying the locations for particular traits within the pea's genetic map.

"The more work we can do with genetic locations and molecular techniques, the more efficient we will be," says Bueckert.

Additionally, the team will look for traits other than flowering duration and pod numbers that can contribute to heat tolerance. For example, the team has already determined that semi-leafless varieties are better at tolerating heat than leafy varieties. Its future research will also focus on uncovering more of these traits.

The research was published in the journal Crop Science.


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