Fungal root endophytes colonization of moist meadow forbs in 2017 at Niwot Ridge LTER site

Fungal root endophytes play an important role in plant nutrition,
helping plants acquire nutrients in exchange for photosynthates. We
sought to characterize the progression of root colonization by
arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE), and
fine root endophytes (FRE) over an alpine growing season, and to
understand the role of the host plant and environment in driving
colonization levels. We sampled four forbs on a regular schedule from
June 26th – September 11th from a moist meadow (3535 m.a.s.l) on Niwot
Ridge, Rocky Mountain Front Range, Colorado, USA. We quantified the
degree of root colonization by storage structures, exchange
structures, and hyphae of all three groups of fungi. AMF and FRE
percent colonization fluctuated significantly over time, while DSE did
not. All AMF structures changed over time, and the degree of change in
vesicles differed by plant species. FRE hyphae, AMF arbuscules and AMF
vesicles peaked late in the season as plants produced seeds. AMF
hyphae levels started high, decreased, and then increased within 20
days, highlighting the dynamic nature of plant-fungal interactions.
Overall, our results show that AMF and FRE, not DSE, root colonization
rapidly changes over the course of a growing season and these changes
are driven by plant phenology and seasonal changes in the environment.