ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Symbiotic Interactions
Dihydrojasmone from antifungal bacterial endophytes as a biocontrol agent against leaf spot pathogens threatening the endangered Tertiary relict plant Parrotia subaequalis
Provisionally accepted
- 1Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China
- 2Yili Normal University, Gulja, China
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Parrotia subaequalis, an endangered Tertiary relict species endemic to eastern China, holds significant values for both evolutionary ecology and ornamental horticulture. However, it is increasingly threatened by leaf spot disease. The causal pathogens and the potential role of bacterial endophytes in disease suppression remain uncharacterized. In this study, fungal pathogens were isolated from diseased leaves collected from native habitats and their pathogenicity was confirmed by Koch’s postulates. Four strains, Alternaria sp. S1, Schizophyllum sp. S2, Diaporthe sp. S5, and Botryosphaeria sp. S6, were confirmed as causal agents of leaf spot disease, with S5 causing the most severe symptoms. Simultaneously, 206 bacterial endophytes were isolated from the non-lesioned portions of diseased leaves and screened for their antagonistic activity, resulting in 25 strains exhibiting strong inhibition against fungal pathogens. Among them, Bacillus species showed the strongest antagonistic effects. Additionally, the antifungal potential of their secondary metabolites was evaluated and analyzed using untargeted metabolomic profiling, which identified 103 bacterial metabolites. Seven abundant metabolites were tested for their antifungal activity, revealing that dihydrojasmone (DJ) and δ-tridecalactone (DT) significantly inhibited fungal growth. DJ displayed broad-spectrum inhibition, suppressed fungal melanin synthesis, and induced hyphal deformation, while DT exerted weaker but significant effects against S2 and S6. Overall, this study provides the first identification of fungal pathogens responsible for leaf spot disease in P. subaequalis. The strong antifungal activities of endophytic Bacillus species and their metabolites were demonstrated, highlighting their promise as eco-friendly biocontrol agents.
Keywords: Parrotia subaequalis, bacterial endophytes, Fungal pathogens, biocontrol, Dihydrojasmone, δ-tridecalactone
Received: 29 Aug 2025; Accepted: 14 Nov 2025.
Copyright: © 2025 Yang, Liu, Zhu, Quan, Shen, Wang and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Ren Wang, rwang@cnbg.net
Jiayu Zhou, zhoujiayu@cnbg.net
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