How Does Plasma-Generated Gas Aid in Plant Pathogen Defense?

Plant leaves.
Plasma may play an important role in plant immunity. (Image: Venus Kaewyoo via Dreamstime)

Plasma, the fourth state of matter that researchers have exploited to generate a gas that may activate plant defense against widespread diseases, is included in the flash of lightning and the dance of the aurora borealis. But how does it works in terms of plant protection? 

Let’s dig deeper. 

What is plasma?

Plasma is a superheated matter that is so hot that electrons are ripped from atoms, creating an ionized gas. It makes up more than 99 percent of the visible universe.

In the night sky, plasma appears as stars, nebulas, and even auroras that occasionally ripple across the north and south poles. The lightning bolt that shatters the sky, like the neon signs adorn our city streets, is plasma. And so is our Sun, the star that makes life on Earth possible.

Plasma is often called “the fourth state of matter,” along with solid, liquid, and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma — a soup of positively charged particles (ions) and negatively charged particles (electrons).

In the night sky, plasma appears as stars, nebulas, and even auroras occasionally ripple across the north and south poles.
In the night sky, plasma appears as stars, nebulas, and even auroras occasionally ripple across the north and south poles. (Image: Dgmate via Dreamstime)

Scientific study on plant immunity

The researchers from Tohoku University in Japan published their findings in PLOS One on June 24, 2022.

“Currently, chemical pesticides are the basis of disease prevention in agriculture, but they may contaminate the soil and destroy the environment,” said Sugihiro Ando, an associate professor of Tohoku University’s Graduate School of Agricultural Science.

 “We must create plant disease management methods that will aid in establishing a sustainable agricultural system. 

“Plant immunity is one of the most successful disease management approaches since it takes advantage of plants’ intrinsic resistance and has a low environmental impact.” Said the researchers. 

Plant immune system

According to the research, using previously built equipment that creates plasma from the air, the researchers generated dinitrogen pentoxide, a reactive nitrogen species (RNS). 

Like reactive oxygen species (ROS), this molecule causes cell damage and activates distinct stress responses in organisms.

“It is generally recognized that reactive species are significant signaling molecules in plant immune response,” Ando said. 

“However, the particular physiological role of dinitrogen pentoxide is unknown.” “When plants detect an infectious stimulus from a disease, they create reactive species as a defense reaction. 

The reactive species produced operate as signaling molecules, helping to activate plant immunity.”

Chemical pesticides are the basis of disease prevention in agriculture, but they may contaminate the soil and destroy the environment.
Chemical pesticides are the basis of disease prevention in agriculture, but they may contaminate the soil and destroy the environment. (Image: Suwin Puengsamrong via Dreamstime)

Statement by the research team 

Reactive species are linked to plant hormones such as salicylic acid, jasmonic acid, and ethylene, which help regulate plant immunity; still, the physiological function of dinitrogen pentoxide is poorly understood, said Ando. 

“Since reactive species are known to have important functions in plant immunity, we analyzed whether exposure of plants to dinitrogen pentoxide gas could enhance disease resistance,” Ando explained.

For three days, the researchers subjected thale cress, a tiny plant often used as a model system for scientific study, to dinitrogen pentoxide gas for 20 seconds daily. 

After that, the plants were infected with one of three common plant pathogens: fungus, bacterium, or virus. Plants infected with the fungus or virus exhibited slower pathogen growth, but plants infected with the bacterium had the same rate of proliferation as control plants.

“These findings show dinitrogen pentoxide gas exposure might manage plant disease depending on the pathogen,” Ando added.

The results

A genetic study discovered that the gas boosted the jasmonic acid and ethylene signaling pathways, resulting in the production of antimicrobial chemicals, which Ando believes may have contributed to the observed disease resistance. 

“Dinitrogen pentoxide gas may be used to enhance plant immunity and prevent plant diseases,” Ando added. 

“Without additional ingredients, the gas may be generated utilizing plasma technology from air and energy. When the gas is dissolved in water, it may be converted to nitric acid and used as a plant fertilizer. 

This technique, being a clean technology with minimum environmental impact, can aid in the creation of a sustainable agriculture system.”

Next, the research will examine how their approach works with crops and greenhouse production.

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