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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #418063
Research Project: Disease Management and Improved Detection Systems for Control of Pathogens of Vegetables and Strawberries

Location: Crop Improvement and Protection Research

Title: Endophytic Agrobacterium sp. from strawberry roots suppresses host plant growth

Author
item Leblanc, Nicholas
item Harrigian, Fiona
item Gebben Hernandez, Samantha
item Salgado-Salazar, Catalina
item Eriksen, Renee

Submitted to: Phytobiomes Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2025
Publication Date: 4/7/2025
Citation: LeBlanc, N.R., Harrigian, F.C., Gebben Hernandez, S.J., Salgado-Salazar, C., Eriksen, R.L. 2025. Endophytic Agrobacterium sp. from strawberry roots suppresses host plant growth. Phytobiomes Journal. https://doi.org/10.1094/PBIOMES-01-25-0003-SC.
DOI: https://doi.org/10.1094/PBIOMES-01-25-0003-SC

Interpretive Summary: Endophytes are microorganisms that live inside plants without causing visible disease symptoms. Endophytes can have beneficial effects on plants by increasing plant growth, protecting plants from pathogenic microorganisms that cause disease, and improving tolerance of environmental stress like drought. This research focused on an endophyte called Agrobacterium originally found in roots of healthy strawberry plants. Unexpectedly, applying the endophyte to roots of strawberry reduced plant growth without causing disease symptoms. By sequencing the genome of the endophyte, we found it shared similarities with and was closely related to known types of Agrobacterium, but may represent a new species. This study demonstrates non-pathogenic endophytes that live in plant roots can have negative effects on plant growth without causing disease and may be reducing crop yield in commercial strawberry production.

Technical Abstract: 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 effects of the endophyte on plant growth under growth chamber and greenhouse conditions. The genome assembly of Agrobacterium sp. El2ro-1b was ca. 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 (ANI) of 95.6% and DNA-DNA hybridization (DDH) 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 Agrobacterium sp. El2ro-1b consistently suppressed foliar 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.