Cultivar governs plant response to inoculation with single isolates and the microbiome associated with arbuscular mycorrhizal fungi

Abstract

Plant Growth-Promoting Microbes (PGPM) have the potential to enhance sustainable agriculture, but there is still a limited understanding of how the complex interplay between plant genetic variability, the native soil community, and soil nutrients affects PGPM recruitment. To address this challenge, we investigated the impact of bacteria isolates and arbuscular mycorrhizal fungi (AMF) along with their accompany microbiome (AMFc) derived from a wild chrysanthemum on the growth of five different commercial chrysanthemum cultivars (Chic, Chic 45, Chic Cream, Haydar and Barolo), as well as their rhizosphere microbiomes, within a nutrient-rich complex substrate environment. We found 23 bacterial strains capable of producing siderophore, 14 strains capable of producing Indole-3-acetic acid, and 18 strains capable of solubilizing phosphate. The AMFc had six AMF species, and the bacterial and fungal communities associated with AMF belonged to different phyla. Using generalized joint models, we investigated the impact of the three most effective bacterial strains and the AMFc on plant growth (shoot and root dry mass) while integrating information on plant genotype, environment, and microbes. The impact of PGPM inoculation varied from positive to negative effects depending on the cultivar, with Chic Cream showing the highest increase in root biomass after inoculation with both bacterial strain SMF006 (57 %) and AMFc inoculation (79 %). Our study demonstrates that PGPM from wild relative can impact the growth and assembly of the chrysanthemum root microbiome, but this impact is cultivar-dependent. Furthermore, inoculation with a complex AMF containing community (AMFc) induced greater changes in the rhizosphere microbiome than with a single bacterial isolate. Our study shows that inoculation of a complex community of beneficial microbes results in more effective plant growth promotion.