US researchers seek to boost yield by improving corn’s nitrogen use

The team is focusing on better understanding how nitrogen is used and regulated by corn, and is looking to improve that connection in an effort to boost corn yield while limiting the use of nitrogen-based fertilizers, said Tom Brutnell, director of the enterprise institute for renewable fuels at the Danforth Center.  

The group recently received a three-year grant​ from the US Department of Agriculture’s National Institute of Food and Agriculture to fund the project, he said. The Danforth Center was awarded about $250,000 for its part of the research.

“It’s a pretty complex regulation, and this grant is really to test the regulatory process,”​ he told Feed Navigator. “The tools we’re using to do this are classical genetics – we’re knocking out specific genes we know are used in this process.”​

The team is based at the center and the University of Illinois, and also includes Stephen Moose, professor of crop science at the University of Illinois and Doug Allen a USDA scientist from the Danforth Center, said Brutnell.

Project details​

The initial stages of the project will seek to knock out genes that are known to work with the assimilation of carbon and nitrogen by the plant, he said.

The plan is to alter the plants to see if they can be made more and less efficient in their nitrogen use, he said. The team is aiming to alter the plant’s flux – or how nitrogen and carbon move within the plant from root to shoots, or leaf to ear.

Corn uses carbon and nitrogen to support growth and development, but the process by which levels of each are regulated by the plant is not well understood, he said. “The way we’re approaching this is manipulating genes in photosynthesis and nitrogen utilization,”​ he added.

To study the regulation process and make specific mutations in the plants, the group will be using a new technology, CRISPR/Cas9, said Brutnell. The technology was developed in the last several years and allows for researchers to do precision engineering work targeting specific genes in plants.

“We can target a specific gene, or a nucleotide within that gene,” ​he said. “We can knock out the regulatory process of the gene.”​

Focus on nitrogen​

The group is examining the use of nitrogen by the plants for with the primary goal of limiting the need for additional nitrogen to help farmers in both developed and developing countries, said Brutnell.

In the US, and some other developed countries, the goal would be to offer a plant that needs less nitrogen so that a smaller amount of fertilizer is added to the soil, he said.

“In the US, farmers tend to over fertilize,” ​he said. “They put on more fertilizer than the plants need, because it is water soluble, so it rains then it will wash away.”​

It can act as a relatively inexpensive security blanket for farmers to add extra nitrogen to their fields, he said. But, field runoff that carries an amount of nitrogen can negatively affect streams or rivers, and in some areas it causes algae blooms and has been found in groundwater supplies.

“There are towns in the Midwest where you can’t drink the water in the spring, because the nitrate levels are too high,”​ said Brutnell. “So, there’s a real cost to putting on too much nitrogen.”​

However, in developing countries farmers may face a challenge being able to add nitrogen to the soil as it can be expensive, he said. But, without the nitrogen, crop yields may be lower.

“If we can make plants better, or use a smaller amount of fertilizer more effectively, that will help developing world’s agriculture,” ​he said.  

Long-term benefits​

Depending on the number of crosses or breeding cycles needed to develop the corn, the work may take longer than the three years set for project, said Brutnell.

“We should be able to know we’re on the right track,” ​he said. “It just takes time to make crosses through the corn plants and you’re limited to two crosses a year. So, if have to make multiple crosses it could take three or four years.”​

The group will be watching how the trial plants compare to regular corn plants when growing in a low-nitrogen field, he said.  

If successful, there is a potential that the corn variety will be made commercially available, he said. Additionally, the process may be adaptable for use with other grass-based feed crops like sorghum and crops like rice and wheat.