Endophytic <i>Agrobacterium</i> sp. from Strawberry Roots Suppresses Host Plant Growth

Plants are naturally colonized by endophytic microorganisms that have variable impacts on host fitness without causing disease. This study characterized a novel endophytic Agrobacterium sp. El2ro-1b from strawberry ( Fragaria × ananassa) by generating and analyzing a high-quality genome assembly and testing the effects of the endophyte on plant growth under growth chamber and greenhouse conditions. The genome assembly of Agrobacterium sp. El2ro-1b was approximately 5 Mb, composed of one circular and one linear contig, and lacked plasmids. Phylogenomic methods placed Agrobacterium sp. El2ro-1b in a clade sister to Agrobacterium fabrum (genomospecies G8), showing average nucleotide identity of 95.6% and DNA-DNA hybridization of 63.2% with A. fabrum. Annotation of predicted proteins showed a lack of known virulence factors of pathogenic Agrobacterium spp. or genes that play a role in plant hormone production or regulation. Bacterial inoculations of strawberry seedlings showed that Agrobacterium sp. El2ro-1b consistently reduced shoot and root biomass. Suppression of plant growth was observed when plants were grown with or without fertilization. This research provides novel evidence that endophytic Agrobacterium spp. can have deleterious effects on the growth of their host and raises questions about the underlying genetic mechanisms. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2025.