Plant endophytes and arbuscular mycorrhizal fungi alter plant competition

Abstract

In nature, grasses simultaneously establish multiple symbiotic associations with endophytic fungi and arbuscular mycorrhizal fungi (AMF). The effect of these multiple interactions on competitive interactions between plants remains poorly understood. In this study, we tested whether endophytes and AMF (Glomus mosseae or Glomus etunicatum) alter plant competition between a subordinate plant species that associates with both symbionts (Achnatherum sibiricum) and a dominant plant species, Stipa grandis, that only associates with one symbiont (AMF). And we hypothesized that endophytes can facilitate the coexistence of the subordinate plant species (A. sibiricum) and the dominant plant species (S. grandis). The results demonstrated that endophyte infection significantly enhanced the competitive ability of the subordinate plant species compared to the dominant plant species. The effects of AMF on plant competition were variable and depended on the identity of the AMF species. Glomus etunicatum gave A. sibiricum plants a higher competitive ability, while G. mosseae gave S. grandis a higher competitive ability. Simultaneous infections of both endophytes and AMF in A. sibiricum also altered the competitive relationships with S. grandis. In conclusion, these results suggest that endophytic fungi can facilitate the coexistence of a subordinate plant species with a dominant plant species. Moreover, endophytes could not only affect the competitive ability of the host plant directly but also indirectly by interacting with different AMF to change the growth of competing plant species. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13084/suppinfo is available for this article.

Microbiomes Reduce Their Host’s Sensitivity to Interspecific Interactions

“…to how incorporating host microbiomes may alter our understanding of the maintenance of biodiversity and species coexistence. Although mutualistic microbes have previously been shown to reduce competition between plants, these studies have been limited to interactions between individuals and may not accurately predict population dynamics in a multigenerational context (20)(21)(22). Studies that have used more complex communities in a multigenerational context have tested effects on productivity and community composition, but not interaction strength (19,52).…”

“…It has previously been shown that symbiotic bacteria and fungi can increase bioavailable nutrient pools, therefore benefiting the growth of a eukaryotic host and reducing competition between host individuals (19,20). By measuring the growth of a small number of individual plants as a proxy for reproductive fitness, researchers have found that symbiotic fungi alter competitive interactions between two species of grassland plants (21,22). However, natural systems are comprised of populations, not individuals, and measures of reproductive fitness inherently require multigenerational studies.…”

Removal of Soil Microbes Alters Interspecific Competitiveness of Epichloë Endophyte-Infected over Endophyte-Free Leymus chinensis

“…As AMF was neutral to both EI and EF plants, the modified colonization did not change the completive advantage of EI over EF plants. In a recent study, we found that Epichloë endophyte colonization significantly inhibited AMF colonization of the host grass Achnatherum sibiricum, and the effects of AMF on host competition were variable and depended on the identity of the AMF species [18]. As AMF diversity is high in natural grasslands, and Epichloë endophyte colonization can affect AMF as well as other microbes [32][33][34], we hypothesized that Epichloë endophyte colonization could not only affect the competitive ability of the host directly by changing its growth and resistance, but also indirectly by changing soil microbes.…”

“…Given the occurrence of Epichloë endophyte-improved plant fitness, Epichloë endophytes are assumed to enhance the intra-and interspecific competition ability of host plants [15][16][17][18]. In terms of intraspecific competition, greater shoot and/or root growth in Festuca arundinacea [19,20], Festuca pratensis [21], and Bromus benekenii [22] have been reported in association with the presence of Epichloë endophytes.…”

“…In terms of intraspecific competition, greater shoot and/or root growth in Festuca arundinacea [19,20], Festuca pratensis [21], and Bromus benekenii [22] have been reported in association with the presence of Epichloë endophytes. With respect to interspecific competition, the greater competitive ability of plants harbouring Epichloë endophytes has been documented in F. pratensis [23,24], Poa alsodes [25], Festuca rubra [16] and Achnatherum sibiricum [18]. However, several studies have also reported conflicting results showing neutral to negative effects of endophytes on the competitive ability of the host [26][27][28][29].…”