The Food and Agriculture Organization of the United Nations estimates that 20 to 40 percent of global crop production is lost annually to plant pests and infections by microbial pathogens.
According to the paper, the researchers found the first clue in tomatoes, which contain a class of proteins that behave differently from those found in the immune systems of other plants.
Most plants have two lines of immune defense—one on the cell surface and one inside, dominated by a disease-resistant protein called NLR.
Encoded by disease resistance genes, these proteins recognize specific invading pathogens and flood the immune system, triggering an effective and rapid response and helping the plant deal with enemies.
Usually, the proteins are tightly regulated and present at relatively low levels. But in the heat of battle, when the immune response is activated, it can trigger a “suicide” mechanism leading to cell death and inhibition of plant growth.
But the researchers found that tomatoes contained a class of proteins from the same family that didn’t 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, which can cause the immune system to overreact and even cause cell suicide.
The researchers analyzed the structure of tomato proteins and found that they remain stable by folding into different forms with the help of a small organic molecule involved in the plant’s energy metabolism process.
Cao Yu, a researcher who works in the same lab as Chai, said the identification of the mechanism, including the helper, “has important implications” by providing a new theoretical basis for crop breeding and pest control.
The research could open up new agricultural biotechnologies to improve crop disease resistance without disrupting their normal growth and yield by triggering an excessive immune response, he said.
Scientists have long known that plants, like animals, are equipped with immune systems, with the cloning of the first plant disease resistance gene providing molecular evidence in 1994. However, the biochemical functions of plant NLR proteins remain poorly understood.
Shi, who was a junior assistant professor in Princeton University’s Department of Molecular Biology, recruited Chai as his first postdoctoral fellow in 1999.
In an interview with The Economic Observer in China last year, Shi described his former student as “one of the world’s leading scientists” in his field.
Upon his return to China in 2004, Chai joined the National Institute of Biological Sciences in Beijing as an independent principal investigator, focusing his research on the then-nascent field of plant immunology.
Last August, Chai and his longtime collaborator Zhou Jianmin won China’s prestigious Future Science Prize for pioneering contributions to the understanding of immune mechanisms in plants.
Zhou, a researcher at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, and Chai participated in a US$1 million prize initiated in 2016 by a group of scientists and entrepreneurs to promote basic scientific research in China.
The privately funded award recognizes outstanding scientists in three main areas – life sciences, physical sciences and mathematics and computer science.