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First molecular confirmation of Lasiodiplodia theobromae causing grapevine trunk disease in southern Egypt

Summary

Researchers in Egypt identified a fungus called Lasiodiplodia theobromae as the cause of a serious disease affecting grapevines in the southern region. Using both microscopic examination and genetic analysis, they confirmed the fungus causes dark streaking in grape vine trunks, leading to branch death and decline. When they tested the fungus on grape tissues in the laboratory, it successfully infected all tested samples, showing it is a highly virulent pathogen. The findings suggest farmers need to use disease-resistant grape varieties and implement management strategies to prevent losses.

Background

Grapevine trunk diseases constitute a significant phytopathological concern in Egyptian viticulture, involving multiple wood-associated pathogens. Lasiodiplodia theobromae, belonging to the Botryosphaeriaceae family, is known to cause vascular cankers and grapevine dieback. Although L. theobromae has been reported as a grapevine pathogen in other regions, its occurrence and virulence in Egyptian viticultural systems remain poorly documented.

Objective

This study aimed to characterize L. theobromae isolates from Egyptian vineyards through morphological and molecular analyses, and to evaluate their pathogenicity on grapevine tissues. The research provides new insights into the local epidemiology and pathogenic behavior of L. theobromae, contributing to improved disease diagnosis and management strategies in Egypt.

Results

L. theobromae was confirmed as the causal agent through 100% sequence identity with reference strains and phylogenetic analysis. The pathogen was associated with vascular cankers, dark brown trunk discoloration, pycnidia formation, and grapevine dieback. Disease index values ranged from 60 to 100% across different tissue types, demonstrating high pathogenic potential.

Conclusion

This report confirms L. theobromae as the causative agent of grapevine trunk disease in southern Egypt through integrated morphological and comprehensive molecular analyses. The findings underscore the urgent need for integrated disease management approaches including resistant cultivars, fungicide application, and cultural practices to reduce plant stress and inoculum sources.
  • Published in:Scientific Reports,
  • Study Type:Original Research,
  • Source: 10.1038/s41598-025-32284-4, PMID: 41466030
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