Nuclear exchange generates population diversity in the wheat leaf rust pathogen Puccinia triticina

• Published in: Nature microbiology Vol. 8; no. 11; pp. 2130 - 2141
• Main Authors: Sperschneider, Jana, Hewitt, Tim, Lewis, David C., Periyannan, Sambasivam, Milgate, Andrew W., Hickey, Lee T., Mago, Rohit, Dodds, Peter N., Figueroa, Melania
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2023; Nature Publishing Group
• Subjects: 45; 45/23; 631/326/193; 631/326/421; Australia; Biomedical and Life Sciences; Genomes; Haplotypes; Infectious Diseases; Leaf rust; Life Sciences; Medical Microbiology; Microbiology; Nuclei; Parasitology; Pathogens; Phylogeny; Plant Diseases - microbiology; Puccinia triticina; Triticum - microbiology; Virology; Australia
• ISSN: 2058-5276; 2058-5276
• DOI: 10.1038/s41564-023-01494-9

In clonally reproducing dikaryotic rust fungi, non-sexual processes such as somatic nuclear exchange are postulated to play a role in diversity but have been difficult to detect due to the lack of genome resolution between the two haploid nuclei. We examined three nuclear-phased genome assemblies of Puccinia triticina , which causes wheat leaf rust disease. We found that the most recently emerged Australian lineage was derived by nuclear exchange between two pre-existing lineages, which originated in Europe and North America. Haplotype-specific phylogenetic analysis reveals that repeated somatic exchange events have shuffled haploid nuclei between long-term clonal lineages, leading to a global P. triticina population representing different combinations of a limited number of haploid genomes. Thus, nuclear exchange seems to be the predominant mechanism generating diversity and the emergence of new strains in this otherwise clonal pathogen. Such genomics-accelerated surveillance of pathogen evolution paves the way for more accurate global disease monitoring. Sperschneider et al. generate nuclear-assigned genome assemblies for several isolates of the wheat leaf rust pathogen, Puccinia triticina , and show that repeated nuclei shuffling between clonal lineages has created global populations.