Wheat stem rust recorded for the first time in decades in Ireland

Area of Science:

• Plant Pathology
• Fungal Genetics
• Agricultural Science

Background:

• Wheat stem rust (Puccinia graminis f. sp. tritici) is a significant global threat to wheat production.
• The disease has recently re-emerged in Western Europe after decades of absence.
• In 2020, wheat stem rust was detected in Ireland for the first time in 50 years.

Purpose of the Study:

• To investigate the origin of the 2020 wheat stem rust outbreak in Ireland.
• To genetically characterize Irish Puccinia graminis f. sp. tritici (Pgt) isolates.
• To assess the potential for long-distance dispersal of pathogenic fungal spores.

Main Methods:

• Transcriptome sequencing of 12 Irish Pgt-infected wheat samples.
• Comparative genomic analysis with 76 global P. graminis isolates.
• Pathology-based race profiling of Irish, UK, and French Pgt isolates.

Main Results:

• Irish Pgt isolates showed close genetic relationships to Ethiopian and UK isolates of the TKTTF race.
• Two Irish Pgt isolates were assigned to the prevalent TKTTF race group.
• The TKTTF Pgt race is confirmed as prevalent in neighboring European countries.

Conclusions:

• The Irish Pgt outbreak likely resulted from long-distance windborne dispersal of urediniospores from Europe.
• Wheat stem rust is an active and re-emergent threat to Irish wheat production.
• Re-initiation of local disease monitoring is crucial for managing this threat in Western Europe.