University of Nebraska-Lincoln researchers are studying how corn roots adapt to a lack of nitrogen, aiming to make genetic adjustments that could increase, or at least maintain, plant growth and yields without excessive fertilizer application.

The growth and development of maize largely depends on its uptake of nutrients by the roots, so the study of their growth, response and metabolic reprogramming associated with stress conditions becomes an important research focus, said Rajib Saha, assistant professor of chemical and biomolecular engineering, whose research is carried out in collaboration with teams from Penn State and the National Research Institute for Agriculture, Food and the Environment.

Nitrogen fertilizers have a significant impact on the climate, but limiting their use can compromise crop yields, Saha said.

“One of the critical aspects of growing any agricultural product is the amount of necessary micronutrients it can get from the soil,” he said. “The idea is to understand what happens when a plant has to grow under nitrogen deficiency or stress. What kind of changes does the plant go through? If we can understand that better, can we now make some adjustments so that plants can survive or even thrive using less nitrogen?”

Saha’s team created a genome-wide metabolic model for maize root to study its nitrogen use efficiency under nitrogen stress conditions.

“If there is not enough nitrogen, we would intuitively expect the root to go further to recover more nitrogen,” said Niaz Bahar Chowdhury, graduate student and lead author of a new paper. on the research in the Journal of Experimental Botany, which is also highlighted in an Insight article published in the same journal.

Indeed, that’s what the model showed – longer and more robust root biomass as the plant searched for the nitrogen it needed. It’s a different reaction than other parts of the plant, which tend to languish when they don’t get enough nutrients.

“When you as a plant spend so many resources growing roots, it comes at the expense of the rest of the plant,” Saha said. “At the end of the day, your resources are limited. The plant might survive but might sacrifice productivity.

“What is the sweet spot? How could we ensure that it can develop its roots so that it still has enough energy to grow shoots and the yield is not affected? »

Reconstructing and simulating the entire metabolic network encoded in a species, as Saha’s team did, is said to be “genome-wide” because researchers attempt to include all enzymes in the sequenced genome of the species. In this case, reconstructing the network via a computer model allowed the team to examine the systematic impact of the nitrogen-limiting growth regime on root tissue.

The Nebraska researchers identified eight lipids and two metabolites that they believe play a role in the increased root growth that occurs under low nitrogen conditions.

This corn root web builds on work Saha did as a graduate student at Penn State, where he built a similar model, but out of corn husks. The next step will be to build a model for the whole corn plant – root, shoot, leaf and seed – to get a broader idea of ​​how corn plants might adapt to nitrogen deficiency. .

He thinks researchers may be able to adjust gene expression and metabolic levels to further gauge how plants respond and improve their growth under nutrient stress conditions. Ultimately, the results will complement some of the ongoing research being conducted by NSF and Nebraska EPSCresearchers from the Center for Root Rhizobiome Innovation funded by the oR and can be tested in real plots.

Corn root modeling could also help scientists study the effect of other stressors such as phosphate deficiency, salinity, heat stress, drought, heavy metal stresses, rot, etc

The research is funded by a National Science Foundation CAREER to agree; a NSF Program grant established to stimulate competitive research that supports the Roots and Rhizobiomes Innovation Center, awarded to Saha; and the Center for Bioenergetic Innovation, a we Department of Energy research center supported by the Office of Biological and Environmental Research of the DOE Office of Science in which one of the collaborators, Costas Maranas of Penn State, is involved.