The Food and Agriculture Organization of the United Nations estimates that between 20 and 40 percent of global crop yields are lost each year due to plant pests and infections with microbial pathogens.
According to the study, scientists found the first clue in tomatoes, which contain a class of proteins that behave differently than the proteins in the immune systems of other plants.
Most plants have two immune defense lines – one on the surface of their cells and another inside them, dominated by a disease-resistant protein called NLR.
These proteins are encoded by disease resistance genes and recognize specific invading pathogens, flood the immune system and trigger an efficient and rapid response that helps the plant deal with its enemies.
Normally, the proteins are tightly regulated and present in relatively small amounts. But in the heat of the moment, when the immune response is activated, it can trigger a “suicide” mechanism that leads to cell death and inhibits plant growth.
However, the researchers found that there was a class of proteins from the same family in tomatoes that did not seem to follow this pattern.
According to Chai and his colleagues, levels of this protein – called NRC – remain high regardless of whether the plant is attacked, and can trigger an immune system overreaction or even cell suicide.
The researchers analyzed the structure of tomato proteins and found that they remain stable by assembling themselves into different shapes with the help of a small organic molecule that is involved in the plant’s energy metabolism.
Cao Yu, a researcher who works in the same lab as Chai, said the identification of the mechanism, including the helper, “has important implications” as it provides a new theoretical basis for plant breeding and pest control.
The research could lead to new agricultural biotechnologies to improve the disease resistance of crops without affecting their normal growth and yield by triggering an excessive immune response, he said.
Scientists have long known that plants, like animals, have an immune system. Molecular proof of this was provided in 1994 with the cloning of the first plant disease resistance gene. However, little was known about the biochemical functions of plant NLR proteins.
Shi, a young assistant professor in Princeton University’s Department of Molecular Biology, took on Chai as his first postdoctoral fellow in 1999.
Last year, in an interview with China’s Economic Observer, Shi described his former student as “one of the world’s leading scientists” in his field.
After returning to China in 2004, Chai joined the National Institute of Biological Sciences in Beijing as an independent research director and focused his research on the then-young field of plant immunology.
Last August, Chai and his long-time collaborator Zhou Jianmin won China’s prestigious Future Science Prize for their groundbreaking contributions to understanding immune mechanisms in plants.
Zhou, a researcher at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, and Chai shared the $1 million prize, which was established in 2016 by a group of scientists and entrepreneurs to promote basic research in China.
The privately funded prize recognizes outstanding scientists in three main fields – life sciences, physical sciences, and mathematics and computer science.