Nitrogen-fixing genes to decrease use of fertilisers

Scientists have transferred a collection of genes into plant-colonizing bacteria that let them draw nitrogen from the air and turn it into ammonia, a natural fertiliser.

Use less man-made fertilisers

The work could help farmers around the world use less man-made fertilisers to grow important food crops like wheat and corn, according to Washington State University.

The article on the WSU website states that legume crops, such as chickpeas and lentils, require significantly less fertiliser than other crops, because they have developed a symbiotic relationship with bacteria that grow within their root tissues. These bacteria convert nitrogen gas to ammonia through a process called biological nitrogen fixation.

Bacteria take nitrogen from the air and convert it into ammonia for the plants, which use it for energy to grow. The plants in turn provide carbon and other nutrients to the microbes.

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The work could help farmers around the world use less man-made fertilisers to grow important food crops like wheat and corn. – Photo: Hans Prinsen

Plants let bacteria know when they need fixed nitrogen

To work symbiotically, legumes and microbes have evolved to release signals that each can understand. The plants give off chemicals that signal to the bacteria when they need fixed nitrogen. The bacteria produce similar signals to let the plants know when they need carbon.

To develop a synthetic method for this symbiosis between other bacteria and crops, scientists worked to determine the groups of genes in bacteria that enable nitrogen fixing, then add those gene groups into other bacteria.

Massive impact on agriculture costs

According to the scientists, reducing fertiliser requirements could have massive impacts on food availability, energy use and agriculture costs all over the world, since fertilisers are too expensive for many farmers around the world. Without them, many nutritionally valuable foods won’t grow in many areas due to nitrogen-poor soil.