Lentils in bloom. Image credit: Carol Mitchell (CC BY-ND 2.0)

Friends with benefits

The receptor protein NRFe plays an important role in the symbiosis of plants and rhizobia bacteria.

eLife
eLife
Sep 1, 2018 · 3 min read

Microbes — whether beneficial or harmful — play an important role in all organisms, including plants. The ability to monitor the surrounding microbes is therefore crucial for the survival of a species. For example, the roots of a soil-growing plant are surrounded by a microbial-rich environment and have therefore evolved sophisticated surveillance mechanisms.

Unlike most other plants, legumes, such as beans, peas or lentils, are capable of growing in nitrogen-poor soils with the help of microbes. In a mutually beneficial process called root nodule symbiosis, legumes form a new organ called the nodule, where specific soil bacteria called rhizobia are hosted. Inside the nodule, rhizobia convert atmospheric dinitrogen into ammonium and provide it to the plant, which in turn supplies the bacteria with carbon resources.

The interaction between the legume plants and rhizobia is very selective. Previous research has shown that plants are able to identify specific signaling molecules produced by these bacteria. One signal in particular, called the Nod factor, is crucial for establishing the relationship between these two organisms. To do so, the legumes use specific receptor proteins that can recognize the Nod factor molecules produced by bacteria. Two well-known Nod factor receptors, NFR1 and NFR5, belong to a large family of proteins, which suggests that other similar receptors may be involved in Nod factor signaling as well.

Now, Murakami et al. identified the role of another receptor called NRFe by studying the legume species Lotus japonicus. The results showed that NFRe and NFR1 share distinct biochemical and molecular properties. NRFe is primarily active in the cells located in a specific area on the surface of the roots. Unlike NFR1, however, NFRe has a restricted signaling capacity limited to the outer root cell layer. Murakami et al. found that when NRFe was mutated, the Nod factor signaling inside the root was less activated and fewer nodules formed, suggesting NRFe plays an important role in this symbiosis.

NFR1-type receptors have also been found in plants outside legumes, which do not form a symbiotic relationship with rhizobia. Identifying more receptors important for Nod-factor signaling could provide a basis for new biotechnological targets in non-symbiotic crops, to improve their growth in nutrient-poor conditions.

To find out more

Read the eLife research paper on which this eLife digest is based:

eLife is an open-access journal that publishes outstanding research in the life sciences and biomedicine.
This text was reused under the terms of a Creative Commons Attribution 4.0 International License.

Roots and Shoots

Delving into ground-breaking research in plant science

eLife

Written by

eLife

Cutting jargon and putting research in context

Roots and Shoots

Delving into ground-breaking research in plant science

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade