Detection of Pestalotiopsis abbreviata sp. nov., the Causal Agent of Pestalotiopsis Leaf Blight on Camellia japonica Based on Metagenomic Analysis

Summary

Researchers discovered a new fungal species called Pestalotiopsis abbreviata that causes leaf disease on Camellia japonica, an ornamental tree popular in Korea. Instead of using traditional time-consuming laboratory methods, they used advanced genetic sequencing (metagenomic analysis) to quickly identify the fungus among hundreds of other microbes living on the tree leaves. This new approach is faster and more accurate than old methods, making it easier to monitor and manage plant diseases in the future.

Background

Pestalotiopsis species are significant fungal pathogens causing leaf blight and leaf spot diseases on Camellia japonica, an important ornamental tree species widely cultivated in East Asia. Traditional culture-based diagnostic methods are labor-intensive and time-consuming, and the coexistence of multiple pathogens with endophytes complicates disease diagnosis. Metagenomic approaches offer rapid and accurate alternatives for pathogen detection without relying on culture isolation.

Objective

This study aimed to apply metagenomic analysis targeting fungal ITS regions to identify the causal agent of Pestalotiopsis leaf blight on Camellia japonica. The research combined metagenomic screening with traditional fungal isolation to validate findings and characterize any novel pathogenic species associated with disease manifestation.

Results

Metagenomic analysis identified Pestalotiopsis as the most abundant fungal genus at 31.8% relative abundance, with significantly higher presence in diseased compared to healthy tissues. A novel species, Pestalotiopsis abbreviata, was identified and characterized through traditional isolation and phylogenetic analysis. The pathogenicity of P. abbreviata was confirmed through inoculation trials, with characteristic symptoms developing and the pathogen successfully re-isolated, fulfilling Koch’s postulates.

Conclusion

This study demonstrates that ITS-based metagenomic profiling effectively identifies pathogenic taxa in complex plant microbiomes and can complement traditional diagnostic methods. The discovery of the novel species Pestalotiopsis abbreviata expands understanding of Pestalotiopsis diversity on Camellia hosts. Integration of metagenomic and culture-based approaches provides a robust framework for rapid pathogen detection and effective disease management in ornamental trees.
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