Genetic Diversity and Population Structure of Cronartium ribicola Associated With Blackcurrant (

ABSTRACT

White pine blister rust, caused by Cronartium ribicola , is widely distributed worldwide, including in Poland, and is increasingly relevant for blackcurrant ( Ribes nigrum ) cultivation, where uredinial populations can build up locally. In this study, we assessed the genetic diversity, population structure and sequence‐based taxonomic placement of C. ribicola from commercial blackcurrant plantations in Poland using three dominant multilocus fingerprinting markers, ISSR, RAPD and MP‐PCR, together with ITS rDNA and β‐tubulin sequencing. In total, 207 urediniospore isolates were collected from 32 sampling locations across three seasons (2022–2024). Polymorphism was highest in ISSR (32 polymorphic loci among 33 scored loci) and RAPD (18 polymorphic loci among 20 scored loci), whereas MP‐PCR showed lower resolution (13 polymorphic loci among 27 scored loci). The integrated ISSR + RAPD + MP‐PCR dataset comprised 80 scored loci, of which 63 were polymorphic. PERMANOVA of the combined dataset showed that sampling location was the strongest spatial driver of genetic structure, explaining 66.56% of variation, whereas voivodeship‐level differentiation was weak and not significant after accounting for year. ITS sequences (GenBank PZ006368–PZ006374) clustered within the C. ribicola clade and showed high within‐Poland similarity. β‐tubulin yielded three Polish sequences, GenBank PZ097983–PZ097985, representing at least two sequence types, but provided only limited additional resolution within the current reference framework. These results establish the first plantation‐linked genetic baseline for C. ribicola associated with blackcurrant in Poland and support repeated within‐plantation sampling across years as the most informative surveillance strategy.