Local scientists reveal nitrogen answers

Ti Gong

Local scientists have revealed why legumes can produce their own nitrogen, providing the possibility of reducing the reliance of other plants on nitrogen fertilizers.

Nitrogen is essential for plants to survive and grow. The element is rich in the air, but plants can’t make use of it directly. So, synthetic nitrogen fertilizers are widely employed in farming. While increasing yields, this has also caused severe environmental pollution.

Figures show that China owns 7 percent of cultivated land, produces 21 percent of crops but consumes 35 percent of nitrogen fertilizers.

Among plants, legumes, however, are able to form a symbiotic relationship with nitrogen-fixing soil bacteria called rhizobia attached to the roots of legumes. Legumes supply carbohydrates for rhizobia, and rhizobia capture nitrogen from the air and supply the nitrogen needs to hosts. Surplus nitrogen is released to the soil, to be used by other plants.

However, for over a century, it was not known why only legumes could make it. Wang Ertao and his research team from the Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences have found the answer.

They discovered that acquisition of the SHR-SCR stem cell program in cortical cells enables legumes to have cell division in the cortex. Such stem cell program can also be activated by signal of rhizobia to induce legumes to form root nodules.

The results were published in leading scientific journal Nature on Thursday.