The Food and Agriculture Organization of the United Nations estimates that 20 to 40 percent of global crop production is lost each year due to plant pests and microbial pathogen infections.
According to the paper, the scientists found the first clues in tomatoes, which contain a class of proteins that work differently from those found in the immune systems of other plants.
Most plants have two lines of immune defense, one on the cell’s surface and one inside the cell, and disease-fighting proteins called NLRs dominate these.
These proteins, encoded by disease resistance genes, recognise specific invading pathogens and stimulate the immune system, triggering an efficient and rapid response that enables the plant to deal with its enemy.
Normally, the protein is tightly regulated and present at relatively low levels, but when the immune response is activated during combat, it can trigger a “suicide” mechanism, leading to cell death and inhibiting plant growth.
However, the researchers found that tomatoes contain a class of proteins from the same family that don’t seem to follow this pattern.
Chai and his colleagues say levels of this protein, called NRC, remain high whether the plant is under attack or not, and can trigger an immune system overreaction and cellular suicide.
The researchers analysed the structures of tomato proteins and found that they remain stable by assembling into different shapes with the help of small organic molecules involved in the plant’s energy metabolism.
Kao Yu, a researcher in Chai’s lab, said identifying the mechanism involving the helpers was “significantly significant” as it provided new rationale for crop breeding and pest control.
The research could pave the way for new agricultural biotechnologies to make crops more resistant to diseases without triggering excessive immune responses that prevent normal crop growth and yield, he said.
Scientists have long known that plants, like animals, have immune systems, and molecular evidence was provided in 1994 when the first plant disease resistance gene was cloned. However, the biochemical functions of plant NLR proteins remained largely unknown.
Shi, then a young assistant professor in Princeton’s molecular biology department, hired Chai as his first postdoctoral researcher in 1999.
In an interview with China’s Economic Observer last year, Shi described his former student as “one of the world’s leading scientists” in his field.
Returning to China in 2004, Chai joined the National Institute of Biological Sciences in Beijing as an independent principal investigator, focusing on research into plant immunology, which was still in its infancy at the time.
Last August, Chai and his long-time collaborator Zhou Jianmin were awarded China’s prestigious Future Science Prize for their pioneering contributions to elucidating plant immune mechanisms.
Zhou and Chai, both researchers at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, are joint winners of the $1 million prize, established in 2016 by a group of scientists and entrepreneurs to promote basic scientific research in China.
The privately funded awards recognize outstanding scientists in three major fields: life sciences, physical sciences, and mathematics and computer sciences.
