Two ancient nuclear lineages and divergent reproductive strategies drive global success of the wheat stripe rust pathogen.

Two ancient nuclear lineages and divergent reproductive strategies underpin the global success of Puccinia striiformis f. sp. tritici, with a dominant heterokaryotic population emerging through nuclear exchange.

• Why it matters: Understanding the genetic and reproductive mechanisms driving pathogen diversity is vital for predicting and managing crop diseases that threaten food security.
• What they did: Analyzing population genomics of 507 global isolates and phased genomes, the study traced the divergence of two nuclear lineages, nuclA and nuclB, from a common ancestor 10,000 years ago, and examined their roles during domestication and regional adaptation.
• The result: The findings reveal that host domestication and reproductive strategies fostered the emergence of distinct populations, with recurrent nuclear exchange leading to a highly adaptable heterokaryotic lineage, enabling widespread pathogen success.