Recent plant photosynthate as a driver of ecological and evolutionary processes.

Plants rapidly allocate carbon from photosynthesis belowground via root exudates and root-associated microorganisms. Here we synthesise recent evidence of our understanding of the consequences of this 'fast' pathway of recent photosynthate flux for major ecological and evolutionary processes. This rapid input of plant-derived carbon to soils shapes food webs and drives processes including soil CO2 efflux, nutrient cycling, plant community dynamics, stability of symbioses and evolution of contrasting modes of nutrition, such as parasitism and mycoheterotrophy. We also highlight how seasonality and anthropogenic and natural perturbations likely determine the magnitude and dynamics of this fast pathway across major vegetation types, but these factors remain understudied. Further gaps in understanding include demonstrating causal links between photosynthate flow and key biogeochemical cycling processes and the capture of photosynthate by co-occurring root-associated microorganisms.