In general, plants obtain the nutrients they need for growth and development from the soil through their root systems. One of the most important nutrients is nitrogen, which is essential for key plant functions like photosynthesis, protein synthesis, and DNA/RNA production.

Most plants rely on the nitrogen naturally present in soil or added through fertilisers.

In nature, a unique group of plants, including soybeans, have evolved a special relationship with nitrogen-fixing bacteria in their roots. These bacteria are able to convert nitrogen gas from the air into a usable form that the plant can absorb through its roots. The bacteria live in specialised structures called root nodules that form on the soybean plant’s root system.

Inside these root nodules, the nitrogen-fixing process requires a lot of energy. To support their bacterial partners, a research team led by Professor Boon Leong LIM of HKU School of Biological Sciences, in collaboration with The Chinese University of Hong Kong found that soybean plants have developed an ingenious adaptation – their root cells modify their mitochondria, the “powerhouses” of the cells, to boost energy production.

By increasing mitochondrial activity in the root nodules, the soybean plant is able to provide the considerable energy needed to fuel nitrogen fixation. This gives the soybean plant access to an abundant nitrogen supply, which is crucial for its growth and development.

It’s a remarkable symbiotic relationship, where the plant provides carbon and energy sources for the bacteria, while the bacteria supply the plant with nitrogen nutrients. And it all happens underground, in those unassuming soybean root nodules.

Click here to learn more about the research.

大部分植物從土壤或者化肥來吸收氮作為營養。有趣的是，有些植物如大豆已經進化出與根部固氮細菌的特殊關係——這些細菌能將空氣中的氮氣轉化成植物可吸收的形式。由香港大學生物科學學院林文量教授與香港中文大學合作進行的研究揭示了大豆根部如何提高線粒體活性來支持這種共生關係。