Receptor-mediated exopolysaccharide perception controls bacterial infection

Area of Science:

• Plant-microbe interactions
• Molecular plant pathology
• Symbiotic nitrogen fixation

Background:

• Surface polysaccharides mediate bacterial interactions with host organisms.
• Bacterial exopolysaccharides (EPS) are crucial for legume-rhizobium symbiosis and nodule development.
• Understanding host recognition of bacterial signals is key to symbiosis.

Purpose of the Study:

• Identify plant genes controlling symbiotic bacterial entry into legume roots.
• Characterize the function of the Epr3 receptor-like kinase in Lotus japonicus.
• Elucidate the mechanism of plant recognition of bacterial exopolysaccharides (EPS).

Main Methods:

• Genetic analysis of Lotus japonicus epr3 mutants.
• Biochemical assays for direct binding of EPS by EPR3 protein.
• Bacterial competition assays to assess EPS recognition.
• Expression analysis of Epr3 during symbiosis.

Main Results:

• Epr3 mutants exhibit defects in perceiving purified EPS.
• EPR3 directly binds EPS and distinguishes between compatible and incompatible bacterial strains.
• EPR3 regulates bacterial passage through the plant epidermis.
• Epr3 expression is induced by bacterial Nod factors.

Conclusions:

• EPR3 is a key receptor-like kinase mediating symbiotic bacterial entry.
• Plant recognition of bacterial EPS is essential for symbiosis establishment.
• A two-stage recognition mechanism involving Nod factors and EPS regulates plant-bacterial compatibility.