Double-Stranded RNA Targeting Dicer-Like Genes Compromises the Pathogenicity of Plasmopara viticola on Grapevine

Area of Science:

• Plant Pathology
• Molecular Biology
• Biotechnology

Background:

• Downy mildew, caused by Plasmopara viticola, is a major threat to grapevine production.
• Current management relies heavily on pesticides, necessitating environmentally safer alternatives.
• Spray-induced gene silencing (SIGS) using double-stranded RNA (dsRNA) shows potential for targeted crop protection.

Purpose of the Study:

• To evaluate dsRNA targeting Plasmopara viticola Dicer-like (DCL) genes for SIGS-based grapevine downy mildew management.
• To assess the efficacy of dsRNA in reducing pathogen virulence and disease progression.
• To explore dsRNA as a novel, environmentally friendly agrochemical or resistance strategy.

Main Methods:

• Development and application of a chimeric dsRNA targeting PvDCL1 and PvDCL2 genes of P. viticola.
• Quantification of PvDCL1 and PvDCL2 transcript levels in dsRNA-treated infected grapevine leaves.
• Assessment of dsRNA's protective and curative effects on downy mildew disease progression.

Main Results:

• Exogenous application of PvDCL1/2 dsRNA significantly reduced P. viticola virulence.
• Reduced PvDCL1 and PvDCL2 transcript levels indicated successful RNA interference within the pathogen.
• PvDCL1/2 dsRNA demonstrated both protective and curative activity against downy mildew.

Conclusions:

• PvDCL1/2 dsRNA is a promising tool for managing grapevine downy mildew via SIGS.
• This RNA-based approach offers a potential new generation of agrochemicals or resistant plants.
• SIGS presents an effective and environmentally sound strategy for controlling this devastating grapevine disease.