Rhizosphere Keystone Microbiomes Promote Invasive Plant Growth under PLA and PVC Microplastic Stress: A Comparative Study with Native Species

Global ecosystems are increasingly threatened by the synergistic pressures of invasive plant species and soil microplastic contamination, yet the mechanisms by which microplastics enhance invasive species establishment remain unclear. In this study, we employ a mesocosm experiment using two types of microplastics, biodegradable polylactide (PLA), and nonbiodegradable polyvinyl chloride (PVC), to compare the responses of invasive and native plant species. We measured plant biomass, nutrient fluxes, soil enzyme activities, and microbial communities in the rhizosphere using soil zymography and 16S rRNA gene sequencing. Invasive plants experienced less growth inhibition than native plants under microplastic exposure, accompanied by the selective enrichment of bacterial genera in the rhizosphere such as Arthrobacter, Sphingomonas, Microvirga, and Azospirillum. These microbes were associated with more interconnected and stable microbial networks, which may have enhanced invasive plant tolerance to microplastic-induced stress. Our results suggest that microplastics can reshape rhizosphere microbial communities in ways that have profound implications for ecological restoration and invasive species management. Future research should experimentally validate the functional roles of these enriched microbial taxa in promoting plant resilience under environmental stress.