Evolution of mycorrhiza systems.

Area of Science:

• Plant biology
• Mycology
• Evolutionary biology

Background:

• Most terrestrial plants engage in mutualistic symbiosis with root-infecting mycorrhizal fungi.
• Fossil records and molecular clock dating indicate that all extant land plants originated from an ancestral arbuscular mycorrhizal condition.
• Arbuscular mycorrhizas co-evolved with early land plants ~450-500 million years ago, while ectomycorrhizas and ericoid mycorrhizas evolved later.

Purpose of the Study:

• To explore the evolutionary history and co-evolutionary processes of mycorrhizal symbioses in terrestrial plants.
• To understand the timeline of mycorrhizal symbiosis evolution.
• To investigate the drivers of ongoing mycorrhizal association evolution.

Main Methods:

• Analysis of fossil records.
• Molecular clock dating of plant and fungal lineages.
• Review of existing evidence on plant-fungal genetic interactions and environmental responses.

Main Results:

• Arbuscular mycorrhizal symbiosis is ancient, dating back to the initial colonization of land by plants.
• Subsequent evolution of ectomycorrhizas and ericoid mycorrhizas is linked to soil conditions and vegetation types.
• Mycorrhizal associations result from diffuse coevolutionary processes, with ongoing parallel evolution driven by environmental changes.

Conclusions:

• Mycorrhizal symbioses are fundamental to terrestrial plant life, with deep evolutionary roots.
• The evolution of different mycorrhizal types reflects adaptation to changing terrestrial environments.
• Environmental change continues to shape the parallel evolution of plant and fungal partners in these vital symbioses.