A native parasitic plant and soil microorganisms facilitate a native plant co-occurrence with an invasive plant.

Invasive plants often interact with antagonists that include native parasitic plants and pathogenic soil microbes, which may reduce fitness of the invaders. However, to date, most of the studies on the ecological consequences of antagonistic interactions between invasive plants and the resident biota focused only on pairwise interactions. A full understanding of invasion dynamics requires studies that test the effects of multiple antagonists on fitness of invasive plants and co-occurring native plants. Here, we used an invasive plant , a co-occurring native plant and a native holoparasitic plant to test whether parasitism on interacts with soil fungi and bacteria to reduce fitness of the invader and promote growth of the co-occurring native plant. In a factorial setup, and were grown together in pots in the presence versus absence of parasitism on by and in the presence versus absence of full complements of soil bacteria and fungi. Fungicide and bactericide were used to suppress soil fungi and bacteria, respectively. Findings show that heavy parasitism by caused the greatest reduction in biomass when soil fungi and bacteria were suppressed. In contrast, the co-occurring native plant experienced the greatest increase in biomass when grown with heavily parasitized and in the presence of a full complement of soil fungi and bacteria. Taken together, our results suggest that selective parasitism on susceptible invasive plants by native parasitic plants and soil microorganisms may diminish competitive ability of invasive plants and facilitate native plant coexistence with invasive plants.