A novel experimental system using the liverwort Marchantia polymorpha and its fungal endophytes reveals diverse and context‐dependent effects

Abstract

Fungal symbioses are ubiquitous in plants, but their effects have mostly been studied in seed plants. This study aimed to assess the diversity of fungal endophyte effects in a bryophyte and identify factors contributing to the variability of outcomes in these interactions. Fungal endophyte cultures and axenic liverwort clones were isolated from wild populations of the liverwort, Marchantia polymorpha. These collections were combined in a gnotobiotic system to test the effects of fungal isolates on the growth rates of hosts under laboratory conditions. Under the experimental conditions, fungi isolated from M. polymorpha ranged from aggressively pathogenic to strongly growth-promoting, but the majority of isolates caused no detectable change in host growth. Growth promotion by selected fungi depended on nutrient concentrations and was inhibited by coinoculation with multiple fungi. The M. polymorpha endophyte system expands the resources for this model liverwort. The experiments presented here demonstrate a wealth of diversity in fungal interactions even in a host reported to lack standard mycorrhizal symbiosis. In addition, they show that some known pathogens of vascular plants live in M. polymorpha and can confer benefits to this nonvascular host. This highlights the importance of studying endophyte effects across the plant tree of life.

On plant defense signaling networks and early land plant evolution

“…For example, a recent study by Nelson and colleagues [22] describes several growth-promoting endophytes associated with the liverwort Marchantia polymorpha , providing fertile ground for future Evo-MPMI research (see [23]). Other Marchantia species were shown to engage in mutualistic interactions with Glomeromycota [24,25].…”

Taking the step: from Evo‐Devo to plant–microbe interaction evolution with the liverwort Marchantia

“…provide the Evo‐MPMI community with a unique resource that opens many avenues for future studies on both beneficial and detrimental plant–microbe interactions. On the beneficial side of the spectrum, Nelson et al . found that the most positive growth responses induced by species of the Colletotrichum and Nemania genera were modulated by nutrient availability, with stronger positive effects on plant growth in normal or high nutrient conditions compared to nutrient‐limiting conditions.…”

“…In addition to the findings described in their article, Nelson et al . provide the Evo‐MPMI community with a unique resource that opens many avenues for future studies on both beneficial and detrimental plant–microbe interactions.…”

“…In this issue of the New Phytologist (pp. 1217–1232), Nelson et al . investigated the diversity of fungal endophytes found in field populations of M. polymorpha sampled in North America.…”

“…This collection of almost 50 ascomycete species represents a unique snapshot of the diversity of M. polymorpha– fungi interactions in the wild. Using this extended collection, Nelson et al . tested the effect of the different fungal isolates in a series of experiments performed on axenic cultures of M. polymorpha .…”