Pectin modifications at the symbiotic interface

Plant cells are surrounded by a structured cell wall, which not only defines cell shape but also provides a structural barrier for protection against pathogen infection. However, the presence of this barrier does not impede the establishment of mutualistic symbioses between plants and several microbes (e.g. ectomycorrhizal fungi, arbuscular mycorrhizal fungi, and rhizobia). To establish such beneficial associations, symbiotic microbes need to colonize the plant tissues via intercellular and/or intracellular infection, a process that requires cell wall modifications. Although cell wall composition and changes during this process have interested researchers for years, the functional characterization of the molecular players involved is still limited. In this viewpoint, based on several new studies, I discuss how the PME-PL/PG pathway mediates cell wall pectin modifications at the symbiotic interface and highlight further research directions which can broaden our understanding of how beneficial root symbioses are established.

Automated summary

Plant cells are surrounded by cell walls that define cell shape and protect against pathogens, but do not impede mutualistic symbioses between plants and microbes. Symbiotic microbes modify cell wall pectin to colonize plant tissues, but the molecular players involved are not well-characterized. This viewpoint discusses the role of the PME-PL/PG pathway in mediating cell wall modifications and highlights the need for further research to understand how beneficial root symbioses are established.