Potential Biocontrol Microorganisms Causing Attenuated Pathogenicity in Plasmopara viticola

Area of Science:

• Plant Pathology
• Microbiology
• Biocontrol

Background:

• Plasmopara viticola, the causal agent of grape downy mildew (GDM), exhibits reduced pathogenicity upon repeated subculturing.
• The underlying mechanisms for this attenuation and potential for biological control agents remain underexplored.

Purpose of the Study:

• To investigate the causes of pathogenicity attenuation in Plasmopara viticola during subculture.
• To identify and evaluate microbial agents associated with P. viticola for their biocontrol potential against GDM.

Main Methods:

• Isolation and culturing of microbes from different generations of P. viticola.
• Assessment of biocontrol efficacy of isolated microbial strains on GDM incidence.
• Identification of effective biocontrol strains using morphological and molecular techniques.

Main Results:

• Subculturing P. viticola led to decreased GDM incidence and a shift in microbial populations.
• Four specific microbial strains (K2, P1, P5, K7) increased in population density with subculturing.
• Bacterial strain K2 (Curtobacterium herbarum) and fungal strains P1 (Thecaphora amaranthi) & P5 (Acremonium sclerotigenum) demonstrated significant biocontrol efficacies (87.5-100.0%) against GDM.

Conclusions:

• Curtobacterium herbarum, Thecaphora amaranthi, and Acremonium sclerotigenum are key contributors to P. viticola pathogenicity attenuation.
• These identified strains exhibit potent biocontrol activity against grape downy mildew.
• This study is the first to report the biocontrol potential of C. herbarum and T. amaranthi against GDM.