Gas produced by plasma helps protect plants against pathogens

The lightning and dancing auroras contain a fourth state of matter called plasma, which researchers have harnessed to produce a gas that can activate plant immunity against widespread diseases.

The team, based at Tohoku University in Japan, published their findings on 24 June in PLOS 1.

“Currently, chemical pesticides are the mainstay of disease control in agriculture, but they can contaminate the soil and harm to the ecosystem,” said paper author Sugihiro Ando, ​​an associate professor at Tohoku University’s Graduate School of Agricultural Science. “We need to develop plant disease control technologies that can help establish a tough farming system. The use of plant immunity is one of the most effective methods of disease control because it uses the innate resistance of plants and has little affect on the environment.”

Using their previously developed device that derives plasma from air, the researchers produced dinitrogen pentoxide, a reactive nitrogen species (RNS). This molecule is related to reactive oxygen species (ROS), in that they damage cells and trigger specific stress responses in organisms.

“It It is well known that reactive species are important signaling factors in plant immune response, but the specific physiological function of dinitrogen pentoxide is poorly understood,” Ando said. “Plants produce reactive species as a defense response when they perceive an infectious stimulus from a pathogen. The reactive species generated function as signaling molecules that contribute to the activation of plant immunity.”

According to Ando, ​​the reactive species are related to plant hormones such as salicylic acid, jasmonic acid and ethylene, which help regulate plant immunity, but the physiological function of dinitrogen pentoxide is poorly understood.

“Since reactive species are known to have important functions in plant immunity, we analyzed that weather exposure of plants to dinitrogen pentoxide could improve disease resistance,” Ando said.

Researchers exhibited Arabis, a small plant commonly used as a model system for research scientist, to dinitrogen pentoxide for 20 seconds a day for three days. The plants were then infected with one of three common plant pathogens: a fungus, bacteria or virus. Plants with the fungus or virus showed suppressed progression of the pathogen, while those with the bacterium had similar proliferation to control plants.

“These results suggest that exposure to dinitrogen pentoxide could control plant diseases depending on the type of pathogen,” Ando said.

Genetic analysis revealed that the gas specifically activated the jasmonic acid and ethylene signaling pathways and appeared to lead to the synthesis of antimicrobial molecules, which Ando suggests may have contributed to the observed disease resistance. “Nitrous pentoxide gas can be used to activate plant immunity and control plant diseases,” Ando said. “Thanks to plasma technology, gas can be produced from air and electricity, without special materials. The gas can also be converted into nitric acid, when dissolved in water, and used as plant fertilizer. This technology can contribute to the construction of a long-lasting agricultural system as a clean technology with minimal influence on the environment.”

Next, the researchers plan to study how their technology works with greenhouse crops and tradition.


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