This is the conclusion reached by professors of molecular biology Kasper Rijkjer Andersen and Simona Ridottoiv at Aarhus University.
Their recent research sheds light on a very important biological indicator that might help reduce agriculture’s heavy reliance on synthetic fertilizers.
Plants need nitrogen to grow, and most crop species can only obtain it through fertilization. A small group of plants, including peas, clover and beans, can grow with none additional nitrogen. They do that by partnering with specific bacteria that convert nitrogen from the air right into a form that plants can absorb.
Unlocking the secrets behind natural nitrogen fixation
Scientists around the globe are working to grasp the genetic and molecular basis of this natural nitrogen-fixing ability. The hope is that the trait can eventually be introduced into major crops akin to wheat, barley and maize.
If harvested, these crops can supply their very own nitrogen. This change would cut back the necessity for synthetic fertilizers, which currently represent about two percent of worldwide energy consumption and generate significant CO2 emissions.
Researchers at Ahres University have now identified small receptor changes in plants that cause them to temporarily turn off their immune defenses and enter right into a cooperative relationship with nitrogen-fixing bacteria.
How plants determine between defense and cooperation
Plants depend on cell surface receptors to sense chemical signals from microorganisms within the soil.
Some bacteria release compounds that warn plants that they’re “enemies,” prompting defensive motion. Others indicate that they’re “friends” who can provide nutrients.
Legumes like peas, beans and clover allow special bacteria to enter their roots. Within these root tissues, bacteria convert nitrogen from the environment and share it with the plant. This partnership, often called symbiosis, is why fruit can grow without artificial fertilizers.
Researchers at Ahres University found that this ability is strongly influenced by just two amino acids, which act as small “building blocks” inside the root protein.
“This is a remarkable and important finding,” says Simona Ridotto.
The root protein acts as a “receptor” that reads signals from the bacteria. This determines whether the plant prompts its immune system (alarm) or accepts the bacteria (symbiosis).
The team identified a small region within the receptor protein that they named symbiosis detector 1. This region acts like a switch that controls which input messages the plant receives.
By modifying just two amino acids inside this switch, the researchers altered a receptor that normally triggers immunity in order that it as a substitute initiates symbiosis with nitrogen-fixing bacteria.
“We have shown that two small changes can cause plants to alter their behavior at a critical point – from rejecting bacteria to cooperating with them.”
Increasing the potential of major food crops
In laboratory experiments, researchers successfully engineered this transformation in a plant. They then tested the concept in Joe and located that the mechanism worked there as well.
“It’s remarkable that we are now able to take a receptor from barley, make small changes to it and then get nitrogen fixing working again,” says Kasper Rijkjer Andersen.
Long-term potential is significant. If these modifications will be applied to other grains, it might eventually be possible to find a way to repair nitrogen, like breeding wheat, corn, or rice.
“But we have to find other, essential keys first,” Ridotto noted.
“Only a very small number of crops can perform symbiosis today. If we can extend this to widely used crops, it could really make a big difference in how much nitrogen needs to be applied.”