The coming age of evoMPMI: origin and evolution of the plant immune system
Evolutionary molecular plant-microbe interactions (EvoMPMI) is an emerging field to bridge the gap between mechanistic molecular phytopathology and evolutionary studies. However, EvoMPMI research is currently challenging due to the scarcity of robust pathogenic model systems in early diverging land plants. Liverworts are amongst the earliest diverging land-plant lineages, and Marchantia polymorpha has emerged as a liverwort model system for evolutionary studies. However, the molecular mechanisms controlling plant-pathogen interactions in this early diverging land plant lineage remain largely unknown.
Selena Giménez-Ibañez will describe a robust experimental plant-bacterial pathosystem for evoMPMI studies and discover that an ancestral arms race governs plant-microbe interactions between M. polymorpha and the hemi-biotrophic pathogenic bacteria Pseudomonas syringae. Selena's group work shows that ancient phytohormone defensive networks govern M. polymorpha-P. syringae interactions. Altogether, their results demonstrate that the basic structure of the plant immune system of extant angiosperms is evolutionarily ancient and conserved in early diverging land plants. This basic immune system may have been instrumental for land colonization by the common ancestor of land plants.