Evidence for invasional meltdown in plant fungal co invasions

Abstract

Invasive symbiotic fungi have been transported around the world, but their role in the shaping of ecosystems is not fully understood. We experimentally tested whether the invasiveness of ectomycorrhizal fungi (EMF) affects the performance of their invasive and non-invasive plant hosts, focusing on the interaction between pine trees and widespread host specific EMF in the genus Suillus. We individually inoculated pine species that span a gradient of invasiveness with Suillus species that vary in invasiveness. We found that pine performance responded positively to EMF invasiveness, particularly in highly invasive pine species, which underperformed when inoculated with less invasive EMF. Although invasive EMF species exhibited greater root colonization in all pine species, less invasive pine species had a weaker growth response to EMF invasiveness. Our findings provide evidence of fungal invasiveness as a crucial factor in plant host performance, especially in symbiotic interactions with highly invasive plants, reinforcing the concept of invasional meltdown.