Positive feedback between mycorrhizal fungi and plants influences plant invasion success and resistance to invasion.

Qian Zhang,Shuijin Hu,Jianjun Tang,Haishui Yang,Xin Chen,Ruyi Yang,Marcel Van der Heijden

doi:10.1371/journal.pone.0012380

Abstract

Negative or positive feedback between arbuscular mycorrhizal fungi (AMF) and host plants can contribute to plant species interactions, but how this feedback affects plant invasion or resistance to invasion is not well known. Here we tested how alterations in AMF community induced by an invasive plant species generate feedback to the invasive plant itself and affect subsequent interactions between the invasive species and its native neighbors. We first examined the effects of the invasive forb Solidago canadensis L. on AMF communities comprising five different AMF species. We then examined the effects of the altered AMF community on mutualisms formed with the native legume forb species Kummerowia striata (Thunb.) Schindl. and on the interaction between the invasive and native plants. The host preferences of the five AMF were also assessed to test whether the AMF form preferred mutualistic relations with the invasive and/or the native species. We found that S. canadensis altered AMF spore composition by increasing one AMF species (Glomus geosporum) while reducing Glomus mosseae, which is the dominant species in the field. The host preference test showed that S. canadensis had promoted the abundance of AMF species (G. geosporum) that most promoted its own growth. As a consequence, the altered AMF community enhanced the competitiveness of invasive S. canadensis at the expense of K. striata. Our results demonstrate that the invasive S. canadensis alters soil AMF community composition because of fungal-host preference. This change in the composition of the AMF community generates positive feedback to the invasive S. canadensis itself and decreases AM associations with native K. striata, thereby making the native K. striata less dominant.

Highlights

Because of their ubiquity and presumed low level of host specificity, arbuscular mycorrhizal fungi (AMF) have been generally believed to play a minor role in mediating the invasion of exotic plants [1]
The spore composition of the AMF community differed under the two hosts (Fig. 1): after the two growing seasons in experiment 1, Glomus geosporum spores were dominant under the invasive host (F1,14 = 37.64, P = 0.000) while Glomus mosseae spores were dominant under the native host (F1,14 = 89.71, P = 0.000) (Fig. 1A)
Changes in the abundance of G. mosseae in native roots based on DNA According to the nested polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)-sequencing method in experiment 2, the relative abundances of DNA G. mosseae and G. geosporum in roots of native K. striata were changed when K. striata was grown in the soil conditioned by S. canadensis under both monoculture (F1,6 = 56.50, P = 0.000 and F1,6 = 590.79, P = 0.000 for G. mosseae and G. geosporum respectively) and mixture (F1,6 = 110.52, P = 0.000 and F1,6 = 84.98, P = 0.001 for G. mosseae and G. geosporum respectively)

Summary

Introduction

Because of their ubiquity and presumed low level of host specificity, arbuscular mycorrhizal fungi (AMF) have been generally believed to play a minor role in mediating the invasion of exotic plants [1]. Experiments demonstrated that the identity of AMF species can impact the performance of invasive plants [11,12]. This evidence of specific host-fungal interactions suggests that AMF could affect plant invasion. Invasive species could be more successful in the presence of certain AMF species, and this could increase the abundance of those AMF species [11] and possibly change the AMF community composition. This assumption, has rarely been experimentally tested

Methods

Results

Conclusion