Wang Ertao's research group reveals a new mechanism of nodule symbiosis signal transduction

On July 2, 2021, the international academic journal Current Biology published online a research paper entitled "Nod factor receptor complex phosphorylates GmGEF2 to stimulate ROP signaling during nodulation" completed by Wang Ertao's research group at the Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences
.

This study took soybeans as the research object, and revealed a new mechanism in which the guanylate exchange factor GmGEF2 and small G protein GmROPs and the scaffold protein GmRACK1 participate in nodulation symbiotic signal transduction in soybeans

Leguminous plants, such as soybeans, peanuts, alfalfa, etc.
, are important crops and economic crops that provide rich nutrients for humans
.

In addition, legumes also play a vital role in the ecosystem, forming nodules through symbiosis with nitrogen-fixing rhizobia in the soil, and then fix free nitrogen in the air into nitrogen-containing compounds that can be used by themselves

The symbiotic relationship between legumes and rhizobia depends on the complex molecular signal exchange process between plants and rhizobia
.

The receptor-like kinases NFR1 (Nod Factor Receptor 1) and NFR5 on the cell membrane of leguminous plants can recognize the nodulation factors secreted by rhizobia and initiate symbiotic signals, but the molecular mechanism of symbiotic signals from membrane receptors to downstream is unclear.

ROP (Rho-like GTPase of Plants) is a unique type of small G protein in plants, which can regulate many processes in plant growth and development as a molecular switch
.

The activation of ROP is finely regulated by the upstream guanylate exchange factor GEF

The researchers used soybean, an important crop, as research materials, and found that the small G protein GmROP9 and its homologous genes are essential for the establishment of symbiosis
.

RNAi and CRISPR mutants showed a significant decrease in the number of nodules, and the expression of marker genes related to symbiosis was significantly inhibited

The study also found that the receptor-like protein kinase GmNFR1 can phosphorylate the N-terminal serine residue at position 86 of GmGEF2a and enhance the activation of GmROP9 by GEF
.

Interestingly, GmROP9 in its active state can form a complex with receptor-like kinases GmNFR1 and GmNFR5 and the scaffold protein GmRACK1 to initiate a symbiotic signal

The work was completed by Gao Jinpeng and Xu Peng, who have graduated from the research group of Wang Ertao, Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences
.

Graduate students Wang Mingxing, Associate Researcher Zhang Xiaowei, Associate Researcher Yang Jun, and Dr.

　　Link to the paper: https:// align="center">

Model diagram of ROP involved in nodulation symbiosis signal transduction