Global crop introduction drives host jumps, turning native pathogens into emerging diseases

Area of Science:

• Plant Pathology
• Evolutionary Biology
• Genomics

Background:

• Global crop trade facilitates pathogen spread, driving plant disease emergence.
• The introduction of crops into pathogen-rich environments is an underrecognized driver of disease emergence.

Purpose of the Study:

• To investigate the evolutionary history and origins of powdery mildews infecting strawberries and raspberries.
• To determine if these fungi represent single cosmopolitan species or diverse, geographically structured lineages.

Main Methods:

• Multilocus phylogenetic analysis of fresh and herbarium specimens.
• Haplotype network and SplitsTree analysis.
• Molecular clock dating to reconstruct evolutionary timelines.

Main Results:

• Powdery mildews on strawberries and raspberries consist of ancient, host-specialized lineages, not a single species.
• North American and Eurasian strawberry powdery mildew lineages originated from native hosts millions of years ago.
• Raspberry-infecting lineages also exhibit local endemism and host specificity.

Conclusions:

• Emerging plant diseases can result from introducing crops into areas with endemic pathogens adapted to native relatives.
• Accurate taxonomic identification and herbarium genomics are crucial for tracing disease origins.
• Understanding evolutionary pathways is key to managing modern plant epidemics.