Rhizosphere microbiome response to host genetic variability: A trade-off between bacterial and fungal community assembly

Abstract

Rhizosphere microbial community composition is strongly influenced by plant species and cultivar. However, our understanding of the impact of plant cultivar genetic variability on microbial assembly composition remains limited. Here, we took advantage of vegetatively propagated chrysanthemum (Chrysanthemum indicum L.) as a plant model and induced roots in five commercial cultivars: Barolo, Chic, Chic 45, Chic Cream and Haydar. We observed strong rhizosphere selection for the bacterial community but weaker selection for the fungal community. The genetic distance between cultivars explained 42.83% of the total dissimilarity between the bacteria selected by the different cultivars. By contrast, rhizosphere fungal selection was not significantly linked to plant genetic dissimilarity. Each chrysanthemum cultivar selected unique bacterial and fungal genera in the rhizosphere. We also observed a trade-off in the rhizosphere selection of bacteria and fungi in which the cultivar with the strongest selection of fungal communities showed the weakest bacterial selection. Finally, bacterial and fungal family taxonomic groups consistently selected by all cultivars were identified (bacteria Chitinophagaceae, Beijerinckiaceae and Acidobacteriaceae, and fungi Pseudeurotiaceae and Chrysozymaceae). Taken together, our findings suggest that chrysanthemum cultivars select distinct rhizosphere microbiomes and share a common core of microbes partially explained by the genetic dissimilarity between cultivars.