Initial microbial status modulates mycorrhizal inoculation effect on rhizosphere microbial communities.

Area of Science:

• * Soil microbiology
• * Plant-microbe interactions
• * Arbuscular mycorrhizal fungi (AMF) research

Background:

• * AMF are crucial for rhizosphere functioning, influencing plant physiology and soil microbial communities.
• * Understanding how AMF alter these interactions under different conditions remains limited.
• * This study investigates AMF effects on plant biomass and microbial communities in various soil types and plant species.

Purpose of the Study:

• * To assess the impact of arbuscular mycorrhizal fungi (AMF) inoculation on plant biomass and soil microbial communities.
• * To determine how soil sterilization and plant species influence AMF effects.
• * To elucidate the role of initial microbial community structure in AMF-plant interactions.

Main Methods:

• * Cultivation of four plant species (clover, alfalfa, ryegrass, tall fescue) in sterilized and non-sterilized soil.
• * Inoculation with a commercial AMF strain (Glomus LPA Val 1.).
• * Measurement of mycorrhizal colonization, plant biomass, and microbial community (bacteria, archaea, fungi) analysis using qPCR and fingerprinting.

Main Results:

• * AMF inoculation significantly altered microbial communities, decreasing bacterial and archaeal abundance and diversity, particularly in sterilized soil.
• * Soil sterilization did not affect AMF's capacity to modify plant biomass.
• * AMF exerted plant-specific selection pressures on soil microbial communities, indicating host-dependent interactions.

Conclusions:

• * AMF significantly influence rhizosphere microbial community structure, with effects varying by plant species and soil conditions.
• * The initial composition of the rhizosphere microbial community is a critical factor to consider when introducing AMF.
• * AMF inoculation offers a potential avenue for modulating soil microbial ecosystems, but plant-specific responses must be accounted for.