Husker Researchers Using Metabolic Model to Study Temperature Stress on Corn

Jan 31, 2024

By Dan Moser

A research team led by Nebraska scientists has built the largest-ever metabolic model of corn to study how temperature stress affects the plant and how a certain fungus can help alleviate the problem.

The research is an expansion of earlier work with a metabolic model of corn roots that the same team used to study the plant’s nitrogen-use efficiency under nitrogen stress conditions, said Rajib Saha, Richard L. and Carol S. McNeel associate professor of chemical and biomolecular engineering and principal investigator. Saha and the team have expanded the model to comprise the entire plant, not just the roots, allowing for expanded research into the intricate metabolic interactions, their associated molecular underpinning and a variety of stressors that can affect productivity.

The metabolic model is of corn hybrid B73, whose genome is highly prized for making hybrids that are used for food, feed and a variety of industrial uses. Developed at Iowa State University in the early 1970s, this line and its descendants are present in half the parentage of nearly all hybrid corn grown around the world.

The Nebraska-developed multi-organ metabolic model — the largest ever created of corn (or any other plant) — allows scientists to conduct research more efficiently and quickly than field research using actual corn plants. The model can also help field researchers with actual corn plants conduct experiments faster and more efficiently, said Niaz Bahar Chowdhury, a doctoral student working with Saha.

It’s estimated that temperature stress resulting from climate change can reduce corn productivity by 7% to 18%.

“There is a pressing need to develop high-yielding maize genotypes capable of withstanding temperature stress,” Saha said.

Scientists are focusing on how plants’ metabolism can be adjusted to counteract that stress. The team’s study takes a holistic, plant-wide approach rather than looking only at specific elements of the plant, Saha said.

Among other impacts, temperature stress can reduce photosynthesis and carbohydrate synthesis in leaves, reduce starch synthesis in kernels, and affect amino acids and lignin biosynthesis in stalks. Also, temperature stress can damage enzymes and tissues, impair flowering and trigger oxidative stress at the reproductive stage.

Saha’s team expressed excessive heat and cold data into their model, finding that both created so-called “metabolic bottlenecks” that slowed plant growth, but noting that heat was especially problematic. Excessive heat is expected to continue impeding crop growth amid ongoing climate change.

One approach to mitigate temperature stress is to reengineer the plant, creating new hybrids that are less affected by it. While that can be successful, “it’s a very, very long process,” Saha said.

In the other approach, researchers inoculated corn root with a beneficial fungus known as Rhizophagus irregularis, commonly used as a soil inoculant. The new study found that R. irregularis also was successful in reducing metabolic bottlenecks that slow plant growth under heat and cold stress conditions, Saha said. Both whole plant biomass and organ-specific biomass growth rates increased with the fungal treatment. Future research, using the same metabolic model, will focus on how R. irregularis affects plant metabolism under high- and low-nitrogen conditions.

Chowdhury and Saha said the model they have created will be available to researchers who want to study other stresses on corn.

Source : unl.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.