Protease inhibitors decrease the resistance of Vitaceae to Plasmopara viticola

Area of Science:

• Plant Pathology
• Molecular Biology
• Biochemistry

Background:

• Plasmopara viticola requires susceptible grapevines for infection.
• Plant resistance involves defense mechanisms and programmed cell death.
• Caspase-like proteases in plants perform functions analogous to animal caspases.

Purpose of the Study:

• To investigate the role of caspase-like proteases in Plasmopara viticola-grapevine interactions.
• To determine how inhibiting serine and cysteine proteases affects grapevine resistance.

Main Methods:

• Utilized three grapevine varieties with varying resistance levels to P. viticola.
• Treated grapevines with PMSF (serine protease inhibitor) or E-64 (cysteine protease inhibitor).
• Monitored pathogen development microscopically and quantified plant defense stilbenes.

Main Results:

• Protease inhibitor treatments increased P. viticola infection rates in resistant and immune grapevines.
• Inhibitors reduced toxic stilbene production, indicating weakened plant defenses.
• Immune cultivars became resistant, resistant cultivars became susceptible, and susceptible cultivars showed increased sensitivity.

Conclusions:

• Caspase-like proteases play a significant role in grapevine defense against Plasmopara viticola.
• Inhibition of these proteases compromises plant immunity, leading to increased susceptibility.
• Targeting plant proteases offers potential strategies for managing grapevine downy mildew.