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Session: Concurrent Session: Nutrient exchange & role of metabolites in plant-microbe interactions

Rhizobial exo-oligosaccharides and Nod factors cooperatively promote nodulation in Lotus japonicus

Thursday, July 17, 2025

15:15 - 15:35

Location: Room M+N

Presenting Author(s)

CS

Christian Staehelin

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
Guangzhou, Guangdong, CHINA

Author(s)

HR

Hua-Qin Ruan

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
CL

Chun-Lian Li

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
YD

Yu-Juan Dong

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
XY

Xuan Yu

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
SY

Shang-Mei Ye

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
HZ

Han-Yue Zhang

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
JL

Jie Liu

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
RG

Rui-Peng Guo

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
WZ

Wan Zeng

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
LS

Li Song

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
ZX

Zhi-Ping Xie

State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Stress Biology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China

In addition to Nod factors (NFs), exo-oligosaccharides (EOS) derived from rhizobial exo-polysaccharides (EPS) act as symbiotic signals that promote nodule formation on legume roots. In our laboratory, EOS were produced in vitro by enzymatically digesting EPS with the rhizobial glycanase ExoK. Purified EOS were applied to Lotus japonicus roots, and genome-wide transcriptomic analysis was conducted to identify gene expression changes. Mutants of Sinorhizobium sp. NGR234 and L. japonicus were used to explore the roles of EOS and NFs in symbiosis. EOS treatment induced the expression of numerous genes, including those involved in phenylpropanoid biosynthesis. Root exudates from EOS-treated plants showed increased levels of genistein, which can enhance nod gene expression and NF production in rhizobia. EOS and NFs were observed to cooperatively upregulate flavonoid synthesis genes. Inoculation experiments with NGR234 and its mutants showed that EOS, rather than EPS, promotes infection thread formation in L. japonicus. In conclusion, we identified L. japonicus genes regulated by EOS signaling and found that EOS stimulates the production of symbiotic phenylpropanoids, which enhance NF synthesis in rhizobia. The resulting increase in NF production ultimately leads to enhanced NF signaling in L. japonicus.