Aeciospore ejection in the rust pathogen Puccinia graminis is driven by moisture ingress

Area of Science:

• Plant Pathology
• Mycology
• Biophysics

Background:

• Fungi utilize diverse spore discharge mechanisms for dispersal.
• The stem rust pathogen, Puccinia graminis, releases aeciospores from its Berberis host, initiating early-season infections in crops.
• Understanding aeciospore liberation is crucial for managing stem rust epidemics.

Purpose of the Study:

• To develop a theoretical model explaining the ejection mechanics of aeciospore liberation in Puccinia graminis.
• To quantify the forces and speeds involved in aeciospore release.
• To create a tool for assessing and managing stem rust dispersal risk.

Main Methods:

• Development of a theoretical model for aeciospore ejection mechanics.
• Analysis of spore turgidity changes and water film lubrication during spore release.
• Simulation of aeciospore dispersal gradients using source strength estimates.
• Integration of dispersal models into a publicly available web interface.

Main Results:

• The model demonstrates that changes in aeciospore turgidity, coupled with water film lubrication, drive spore expulsion.
• Individual aeciospores can reach ejection speeds ranging from 0.053 to 0.754 m·s⁻¹.
• A web interface was developed to visualize dispersal risk.

Conclusions:

• The study elucidates the physical mechanisms behind aeciospore release in Puccinia graminis.
• The developed model and web interface provide valuable tools for farmers and legislators to assess and mitigate stem rust dispersal risk.
• This research contributes to the development of advanced epidemiological models for controlling stem rust epidemics.