By ANN HINCH
Assistant Editor

URBANA, Ill. — Rapid climate change could have an effect on crop growing patterns in this country in a matter of decades, and this is something corn breeders have to keep in mind when developing new varieties today, so those can adapt when bred further later on.

At the annual AgMasters conference at the University of Illinois earlier this month, Dr. Martin Bohn and Dr. Rita Mumm, both with the University of Illinois (UoI) Department of Crop Sciences, talked about some of the traits that could be desirable for corn over the next few decades. Bohn pointed out that in 2050 – if weather-change patterns continue as one study he cited thinks they will – Illinois should have milder winters and hot, dry summers.

What this means is in the not-too-distant future, it might be possible to plant corn in places it’s not already widely planted (or at all). Changes in climate would also change growing patterns in the Corn Belt. One challenge breeders face, Bohn said, is that corn is already using current carbon dioxide levels efficiently; if those emissions increase with climate change, it really won’t help that crop – but weeds will love the higher levels.

And this is aside from the problems likely to be visited upon future corn by new insects and diseases not yet heard of, as well as increased severity of existing problems; root problems; and the effect of higher temperatures on pollination and stressing weather effects such as flooding.

“If you don’t change anything (now), it might look like this,” Bohn said to his audience, showing a slide of dried, withered, insect-chomped corn plants.
Now that scientists have sequenced the corn genome, he said it allows breeders to more easily locate and control specific genes for the traits they want to market to farmers. The “Green Box” strategy of breeding is to rank traits by desirability, and then develop hybrids accordingly – such as for yield, resistance to certain stressors, quality and the like.

A breeder must be mindful of what generations beyond what they are developing will do with the traits. To illustrate, Bohn had a few audience members play a computer game in which the goal was to select from a number of cultivars in each generation to get the most tall, red plants possible by the fourth or fifth generation.

Using this, he showed why certain selections yielded success or failure in the end result. Sometimes it’s as simple as getting lucky in one’s selection.
“The point of developing cultivars is to cross good with good and get better,” Mumm added, saying the game shows how identifying superior progeny to continue breeding isn’t so easy.

Biotechnology has given breeders an advantage, she said. It used to be a breeder could only create a new variety from two cultivars and had limited control over the end result, but with transgenic research, they can now pull desirable genes from other sources to enhance plants – such as a gene from soil inserted into Bt corn to make it resistant to insects.

She explained hybrids that contain transgenic traits all originate from one fertile, specifically-engineered plant designed to pass along the one or more desired traits. What might lessen a transgenic seed’s performance is “linkage drag,” or less desirable germplasm brought into a new hybrid along with the desired trait in the breeding process.

A trait, Mumm said, does one of three things: it preserves yield potential, enhances it or creates a need for fewer inputs to create a sustainable plant. Those that preserve potential enable the plant to resist or tolerate stresses such as bugs, herbicides or – as is being worked on now – drought.

“The yield potential is built in by breeding,” she said. “Environmental conditions can help reach (the maximum yield), or subtract” from the plant reaching that pinnacle.

Traits that enhance yield potential include those that boost a plant’s natural processes, such as capturing light or more efficient photosynthesis. Lowering inputs for sustainability are traits that maximize a plant’s use of the available nitrogen or intake and synthesis of protein. Helping a plant need less water to do the same work is another goal of the third kind of trait, and Mumm pointed out drought-tolerant varieties could help farmers expand the acreage on which corn is grown in the future.

She said biotech trait-stacking is on the rise. In 2009, there were an average of 2.5 stacked traits per acre of traited corn; by 2020, she said this could be up to 10.3 traits. While several traits packed into one seed might result in an armor-plated plant, she pointed out seed companies have seen lowered yields that concern them, as activating all these traits requires more energy from the plant.

Methods of delivery for engineered traits are also in development. She said Dow AgroSciences is working on EXZACT technology that would allow a gene to be inserted into a specific part of a corn DNA sequence rather than allowing the plant to insert it wherever. This should in theory stabilize the gene to be passed along in breeding.

Also, Chromatin is working on creating an artificial chromosome that could be inserted into corn DNA that would be “loaded up” with engineered genes for specific traits.

But there are things outside of breeding a better seed that can help corn yield grow. One Mumm mentioned is managing weed resistance by varying herbicides from season to season, and using new compounds and tank mixes.

“We wouldn’t think of growing the same corn hybrid on the same ground year after year, after year, after year,” she said. “So why do we use the same chemical year after year?”