Additive and antagonistic interactions between arbuscular mycorrhizal fungi and endophytic fungi dominate effect on plant performance and colonization rate

Inoculation of arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EF) is of primal significance for the development of sustainable agriculture. Currently, the positive effects of inoculation with AMF or EF alone on plant growth have been extensively studied, but the interaction of AMF and EF on plant performance and fungal colonization rate have not been well studied.

We conducted a meta-analysis of 371 observations from 62 full-factor experiments and quantified the interaction between AMF and EF on 14 variables related to plant growth performance and fungal colonization rate.

The results indicated that the inoculation with AMF or EF alone significantly increased the aboveground biomass, total biomass, stomatal conductance and their colonization rate. AMF also significantly increased the plant height (PLH), shoot P content, average root diameter (ARD) and chlorophyll content. Meanwhile, the infection with EF alone also significantly increased belowground biomass and total root length (TRL). Antagonistic interactions were exerted for plant biomass, PLH and mycorrhizal colonization rate (MCR). Additive interactions were observed for root to shoot ratio, TRL, ARD, plant P content, stomatal conductance, chlorophyll content and endophyte colonization rate. And synergies rarely occurred, with only for ARD in forage plants.

Overall, our results confirmed the positive effects of AMF or EF on plant biomass and nutrient absorption, while antagonistic and additive interactions revealed competition between microbial symbionts and independent contributions to plant performance.