Lower Nitrogen Inputs = High Corn Yields - Stacking NitroGenes Could Be The Key

Professor Stephen Moose, who studies maize functional genomics at the University of Illinois, along with graduate fellow Jessica Bubert, shared their findings on the nine genes, termed NitroGenes, they have identified over the last three years that have proven to affect traits involved in improving nitrogen use efficiency (NUE) in corn. NitroGenes are a group of genes identified as having the potential to help power more corn yield with less nitrogen. These genes showed an important impact on NUE-related traits such as stover nitrogen content, grain nitrogen concentration, and kernel number.

The ultimate goal of the research is to increase yields through better nitrogen utilization and lower nitrogen inputs, Moose explained. “The improvement of NUE is something that has been on the radar for many years,” he said. “It’s kind of the holy grail of biotechnology if you can make nitrogen-fixing corn.”

While breeders have tried to accomplish these results for some time, Moose said significant progress has not been made for a few reasons. “When you are measuring yield, there are so many things that affect yield and nitrogen is only one of them. Another problem is actually having environments where you can do these evaluations and can separate the nitrogen from other factors. On top of that, having the right genetics to put into the system to actually see where the differences are is important.”

Moose and researchers at the Moose Functional Genomics lab at the U of I reasoned that combining or stacking these favorable NitroGenes by a breeding approach may improve nitrogen utilization, grain yield, and possibly other agronomic traits.

“We took germplasm that was very well studied, not only by us but by other researchers, and we evaluated it in an environment in which nitrogen is separated from other effects. When you do that you discover that there are genes that have a small effect on NUE on their own. The project is putting those all together to see if we get a whopper—more of an effect combined than individually.”

As part of the 2012 trials, two separate populations were grown: an enriched population and a depleted population. “The enriched population has as many good genes with positive effects as we could get in one line. The depleted population has the least number of those NitroGenes with positive effects,” Bubert explained. 

The populations, which include 20 lines each, are being examined to see if stacking all of the genes together improves nitrogen utilization, yield, and other agronomic traits. “We did see improvement in both yield and nitrogen utilization in our first year trial,” she said. 

The populations represent the theoretical changes that could be made when selecting for changes in these nine NitroGenes simultaneously. Preliminary results indicated that the hybrids enriched for favorable NitroGenes produced higher-averaging nitrogen utilization when grown with either low or high levels of nitrogen supply. Enrichment can result in an 8.8 percent increase in acquired nitrogen (NUtE) within this population, corresponding to a yield increase of 6.9 percent, or 5 to 10 bushels per acre.

“We found that no line has all the good genes,” Moose said. “There are probably more, but those are the nine biggest ones we found in our initial screen. None of our lines have all nine, so we say, ‘let’s try to make one that has all nine, and see what it can do,’” Moose said. 

Moose said he hopes the research will provide direction for how seed companies and the breeding industry produce.

“We had a way to figure out why some lines have better NUE than others. Historically, the corn genome has been so shuffled up that it becomes hard to find the genetic connections, but now we can zero right in on genes and even parts within the genes. We are building upon recent advances in plant genomics, and applying our know how in measuring NUE to the genetic base of current hybrids. Because it is now feasible to identify individual NitroGenes, we felt like we could actually stack them. Now we have results and we’re willing to talk about it,” he said.

With the study now in its second and final season, Moose said that the results from the previous field season indicate that their strategy to “pyramid” NitroGenes is a viable option for improving NUE and nitrogen-dependent yield, which could be translated to current elite germplasm.