The invasive plant, Brassica nigra, degrades local mycorrhizas across a wide geographical landscape.

Sepideh Pakpour,John Klironomos

doi:10.1098/rsos.150300

Abstract

Disruption of mycorrhizal fungi that form symbioses with local native plants is a strategy used by some invasive exotic plants for competing within their resident communities. Example invasive plants include Alliaria petiolata (garlic mustard) and Brassica nigra (black mustard), both non-mycorrhizal plants in the Family Brassicaceae. Although there is clear evidence for mycorrhizal degradation, it is not known if such an effect is widespread across the naturalized range. In this study, we tested the ability of black mustard to degrade the local mycorrhizal symbiosis and supress the growth of native flora from across a variety of locations where black mustard has invaded. We found that the effects on mycorrhizal fungi and on the growth of native plants were consistently negative at the various sites. The present results indicate that degradation of the mycorrhizal symbiosis by black mustard is of general significance, and may be highly problematic considering the large range that it has occupied in open fields across North America.

Highlights

Invasive exotic plants may negatively impact the structure and functioning of communities and ecosystems via a number of mechanisms [1,2,3,4]
In study 1, we found that all native plant species in the field were colonized by arbuscular mycorrhizal (AM) fungi
In studies 2 and 3, native plants were significantly less productive when grown in the invaded field soil (t18 = 2.48, p = 0.02, a reduction of 35.5%; figure 1c) as well as in the soil that was trained by black mustard under greenhouse conditions (t18 = 3.35, p = 0.003, a reduction of 47.8%; figure 1d)

Summary

Sepideh Pakpour and John Klironomos

Disruption of mycorrhizal fungi that form symbioses with local native plants is a strategy used by some invasive exotic plants for competing within their resident communities. Example invasive plants include Alliaria petiolata (garlic mustard) and Brassica nigra (black mustard), both non-mycorrhizal plants in the Family Brassicaceae. We tested the ability of black mustard to degrade the local mycorrhizal symbiosis and supress the growth of native flora from across a variety of locations where black mustard has invaded. We found that the effects on mycorrhizal fungi and on the growth of native plants were consistently negative at the various sites. The present results indicate that degradation of the mycorrhizal symbiosis by black mustard is of general significance, and may be highly problematic considering the large range that it has occupied in open fields across North America

Introduction

Material and methods

Results and discussion