2026-02-11 デラウェア大学(UD)
<関連情報>
- https://www.udel.edu/udaily/2026/february/turfgrass-beneficial-bacteria-protection-against-dollar-spot-fungus-harsh-bais/
- https://www.sciencedirect.com/science/article/pii/S2667064X25004257
- https://www.sciencedirect.com/science/article/abs/pii/S1049964423001378
クリーピングベントグラスにおけるダラースポット病原菌に対するバチルス・サブチリスUD1022による誘導全身抵抗反応は、直接的な拮抗作用によって無効化される Direct antagonism overrides induced systemic resistance response by Bacillus subtilis UD1022 against dollar spot pathogen in creeping bentgrass
Charanpreet Kaur, Erik Ervin, Harsh P. Bais
Plant Stress Available online: 26 November 2025
DOI:https://doi.org/10.1016/j.stress.2025.101158
Graphical abstract
Highlights
- UD1022 application to roots triggers foliar defense response dependent on JA and SA pathways.
- UD1022 priming alone did not reduce dollar spot disease severity in creeping bentgrass.
- UD1022 root priming along with direct foliar treatment reduced disease severity.
- Direct antagonism plays a prominent role in disease control than defense priming.
Abstract
Dollar spot, a major turfgrass disease, poses significant challenges to the turfgrass industry, highlighting the need for sustainable disease management strategies. Plant growth promoting rhizobacteria (PGPR) Bacillus subtilis strain UD1022 (hereafter UD1022) has previously shown ability to inhibit dollar spot pathogen, Clarireedia jacksonii through direct antagonism under in vitro conditions. However, additional investigation is needed to fully understand its role as a biocontrol agent in planta. It is unclear whether UD1022 suppresses dollar spot in creeping bentgrass, and if so, whether the suppression occurs primarily through induced plant defense responses or via direct antagonism. To address these knowledge gaps, we investigate the biocontrol potential of UD1022 against C. jacksonii in creeping bentgrass, focusing on systemic defense responses and direct antagonism mechanisms. Our data showed that plants primed with UD1022 and subsequently inoculated with foliar dollar spot pathogen did not protect plants against the fungal pathogen. In contrast, UD1022 direct application to the leaves with the pathogen led to a 43.6% reduction in disease severity. Gene expression data showed that UD1022 application to roots triggers foliar defense response dependent on jasmonic acid (JA) and salicylic acid (SA) pathways. In addition, plants treated with UD1022 mutants deficient in sporulation, surfactin, and biofilm formation pathways failed to protect plants against the dollar spot pathogen, suggesting the role of these pathways in disease protection and PGPR fitness. Understanding the mechanisms by which PGPR modulate plant immunity could contribute to the development of sustainable turfgrass management approaches.
植物成長促進根圏細菌バチルス・サブチリスUD1022株のドルスポット病原菌(クラリリーディア・ジャクソン)に対するSpo0A依存性抗真菌活性 Spo0A-dependent antifungal activity of a plant growth promoting rhizobacteria Bacillus subtilis strain UD1022 against the dollar spot pathogen (Clarireedia jacksonii)
Charanpreet Kaur, Mike Fidanza, Erik Ervin, Harsh P. Bais
Biological Control Available online: 16 June 2023
DOI:https://doi.org/10.1016/j.biocontrol.2023.105284
Highlights
- PGPR B. subtilis UD1022 showed significant antagonism against dollar spot pathogen C. jacksonii.
- B. subtilis master regulator spo0A gene was required for the antagonism.
- Bacterial volatile compounds and cell free lysate of UD1022 showed no fungal inhibition.
- Morphological changes in C. jacksonii mycelia were observed when exposed to UD1022.
- Creeping bentgrass plots treated with UD1022 had reduced dollar spot incidence as compared to untreated control.
Abstract
Dollar spot is an economically important foliar disease of turfgrass caused by Clarireedia spp. Increased use of chemical fungicides for disease management has possible negative effects on the environment and human health. The quest for eco-friendly alternatives to fungicides is driving the development of new biological strategies for managing dollar spot. In the present study, an analysis of antifungal activity of the plant growth promoting rhizobacteria (PGPR) Bacillus subtilis strain UD1022 (hereafter UD1022) and plant health products (PHPs) (Acibenzolar-S-methyl, kelp extract, fosetyl-Al, and trinexapac-ethyl) against Clarireedia jacksonii for control of the turfgrass fungal disease dollar spot was conducted. In vitro assays revealed that UD1022 has significant inhibitory effects against the mycelial growth of C. jacksonii. Of all the treatments, wild type UD1022 and a non-ribosomal peptide mutant (sfp¯) showed potential antagonism against C. jacksonii with inhibition rate of 17.2 % and 18.4%, respectively. Interestingly a Bacillus-derived broad antifungal compound (surfactin) and PHPs showed no direct antagonistic activity against dollar spot pathogen and were statistically like the untreated control. All the mutants of UD1022 except spo0A¯ showed varying but significant inhibition of the fungal pathogen suggesting that spo0A gene may be directly involved in the antagonism against C. jacksonii. Bacterial volatile compounds (BVCs) of UD1022 may not be involved in antagonism as no fungal inhibition was observed in the indirect assay using split petri plates. Filter sterilized cell free lysate (CFL) as well as heat treated CFL of UD1022 bacterial culture did not show any fungal inhibition indicating a primary role of live bacterial cells and not bacterial-derived or secreted compounds in fungal growth inhibition. The results indicate UD1022 to possess the potential to be extended for the biocontrol of dollar spot of turfgrass.
