SHANGHAI, Jan. 9 (Xinhua) -- A team of Chinese and international scientists has uncovered the precise mechanism behind one of nature's most vital alliances: the partnership between legume plants and nitrogen-fixing bacteria. This finding has the potential to transform future agricultural practices.
The discovery, published in the latest issue of Science, explains how plants and bacteria identify the perfect partner, paving the way for engineered crops that may one day need far less chemical fertilizer.
The study explains how legumes such as soybeans and peas identify and form partnerships with specific rhizobia -- bacteria that help convert atmospheric nitrogen into a usable form for the plant. These interactions result in the formation of root nodules, which act as natural fertilizer factories. Within these nodules, the plants provide sugars to the bacteria, while the bacteria, in turn, supply the plants with fixed nitrogen.
A long-standing mystery has been how plant roots, surrounded by countless microbes, selectively allow only compatible rhizobia to enter. This process begins with plant-secreted chemicals called flavonoids, but the exact mechanism of recognition has remained unclear.
However, a collaborative team led by researchers from the Center for Excellence in Molecular Plant Sciences (CEMPS) of the Chinese Academy of Sciences has solved this puzzle. By determining the detailed 3D structure of a key bacterial protein called NodD bound to a flavonoid signal, they unveiled the exact "lock-and-key" fit that enables specific partner selection. The team identified unique regions in NodD that act as a selective filter, ensuring each bacterial strain responds only to the flavonoid signal produced by its specific host plant.
According to the study, the findings open new pathways for designing more efficient symbiotic systems. In the future, scientists may engineer rhizobia to partner with a broader range of crops -- including cereals like rice and wheat, which do not naturally form such relationships.
"This brings us closer to reducing agriculture's reliance on synthetic nitrogen fertilizers," said Zhang Yu, a researcher at CEMPS. "By understanding this molecular handshake, we can explore creating new beneficial partnerships between plants and microbes."
The research not only decodes a fundamental dialogue in nature but also lays a scientific foundation for designing greener, more sustainable farming systems worldwide, Zhang added. ■
