Combined inoculation with dark septate endophytes and arbuscular mycorrhizal fungi: synergistic or competitive growth effects on maize?

Linlin Xie,Jianxuan Shang,Yinli Bi,Qincheng Hu,Shaopeng Ma,Peter Christie

doi:10.1186/s12870-021-03267-0

Abstract

BackgroundEffects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species.MethodsSuspensions of DSE isolated from Stipa krylovii were prepared at different densities (2, 4, and 8 × 105 CFU mL− 1) and inoculated separately (AMF or DSE) or together (AMF + DSE), to explore their effects on maize growth.ResultsInoculation with AMF or medium and high densities of DSE and combined inoculation (AMF + DSE) increased plant above-ground growth and altered root morphology. Differences in plant growth were attributable to differences in DSE density, with negative DSE inoculation responsiveness at low density. AMF promoted plant above-ground growth more than DSE and the high density of DSE promoted root development more than AMF. Combined inoculation might lead to synergistic growth effects on maize at low density of DSE and competitive effects at medium and high DSE densities.ConclusionsAMF and DSE co-colonized maize roots and they had positive effects on the host plants depending on DSE density. These findings indicate the optimum maize growth-promoting combination of AMF and DSE density and provide a foundation for further exploration of potentially synergistic mechanisms between AMF and DSE in physiological and ecological effects on host plants.

Highlights

Effects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species
We speculate that AMF and low-density DSE colonization were promoted by combined inoculation but niche competition might exist between Sterilized DSE with AMF (AM) and Medium concentration of DSE with AMF (MD) or High concentration of DSE with AMF (HD)
The degree of DSE colonization might be a key factor determining whether the relationship between this fungal group and its plant host is mutualistic

Summary

Introduction

Effects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species. Arbuscular mycorrhizal fungi (AMF) are important soil fungi that inhabit the roots of most terrestrial plant species with which they form potentially symbiotic associations. Xie et al BMC Plant Biol (2021) 21:498 outside the roots to the intraradical mycelium [6] and can promote an effective relationship between plants, bacteria and beneficial fungi [7]. Simulation experiments indicate that inoculation of plants with AMF increases plant biomass and alleviates mechanical damage to the root system [9]. AMF inoculation increases the abundance of certain beneficial bacterial species and decreases that of certain pathogenic fungi in the rhizosphere [10]

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