Evaluation of bacterial endophytes from turfgrass for effective biocontrol of dollar spot disease

Clarireedia spp. are a group of highly destructive phytopathogenic fungi that affect both cool- and warm-season turfgrasses, leading to the development of dollar spot (DS) disease. Biological control presents a promising alternative to chemical methods, offering environmental benefits and eliminating the risk of fungicide resistance development.

A total of 2934 endophytic bacterial strains isolated from turfgrasses were screened for their potential to suppress DS disease in this study. Forty-three strains demonstrated inhibitory effects against Clarireedia jacksonii isolate LT586, with growth inhibition rates (GIRs) ranging from 6.52% to 87.38%. Twenty-eight strains (primarily Pseudomonas and Bacillus spp.) showed > 50% GIR, and 11 of these strains effectively suppressed LT586 without causing turfgrass phytotoxicity. Pot experiments further validated the biocontrol potential of Bacillus cereus strain B694, which exhibited the highest control efficacy, with 92.93% inhibition at 6 days and 88.05% at 11 days post-inoculation. Scanning electron microscopy revealed that B694 formed biofilms on hyphae, degrading its cell walls and inducing atrophy. Transcriptome analysis of B694-treated C. jacksonii LT586 identified 1276 differentially expressed genes (1023 up-regulated; 253 down-regulated). Representative up-regulated genes were associated with chitin and glucan synthesis, sterol and fatty acid metabolism, glutathione metabolism, transmembrane transporters, and cytochrome P450 monooxygenases. These findings suggest that C. jacksonii attempts to maintain cellular function by enhancing cell wall and membrane synthesis, activating antioxidant stress responses, and detoxifying bacterial antimicrobial compounds.

This study provides a theoretical foundation for future investigations into the use of Bacillus cereus B694 as a potential biocontrol agent for DS in turfgrass disease management. © 2025 Society of Chemical Industry.