Unveiling the Evolutionary History of Soybean Rust Pathogen Phakopsora Pachyrhizi

Strategic Insights -

Researchers from the Brazilian Agricultural Research Corporation have made a significant breakthrough in understanding the evolutionary patterns and population structure of the soybean rust pathogen Phakopsora pachyrhizi. The study, which was supported by various organizations including the United States Department of Energy and the Brazilian Ministry of Science, Technology and Innovation-MCTI, analyzed whole-genome data from 45 P. pachyrhizi isolates collected from 1972 to 2017.

The study revealed two distinct evolutionary lineages, Pp1 and Pp2, with lineage Pp1 grouping isolates obtained from 1972 to 1994, and lineage Pp2 formed by more recently collected isolates. The researchers found higher levels of genetic diversity in lineage Pp1, whereas lineage Pp2 exhibited a strong clonal genetic structure with a significant lower diversity. The study also suggested potential somatic hybridization between the two P. pachyrhizi lineages, which was further supported by the observation of genetic admixture in two independent isolates.

Key Takeaways:

  • The study found two distinct evolutionary lineages, Pp1 and Pp2, in the soybean rust pathogen Phakopsora pachyrhizi, with lineage Pp1 grouping isolates obtained from 1972 to 1994 and lineage Pp2 formed by more recently collected isolates.
  • Lineage Pp1 exhibited higher levels of genetic diversity, whereas lineage Pp2 showed a strong clonal genetic structure with a significant lower diversity.
  • The study suggested potential somatic hybridization between the two P. pachyrhizi lineages, which was further supported by the observation of genetic admixture in two independent isolates.
  • The widespread propagation of P. pachyrhizi clonal spores across soybean-growing regions likely explains the absence of a large-scale spatial genetic structure within each lineage.
  • The study found no clear congruence between virulence levels of P. pachyrhizi isolates and their phylogenetic patterns.

Statistics:

  • 45 P. pachyrhizi isolates were analyzed in the study, which were collected from 1972 to 2017.
  • The study revealed two distinct evolutionary lineages, Pp1 and Pp2, with lineage Pp1 containing isolates obtained from 1972 to 1994 and lineage Pp2 formed by more recently collected isolates.
  • Lineage Pp1 exhibited a higher genetic diversity index (78.2%) compared to lineage Pp2 (15.1%).
  • The study found that two independent isolates (TW72-1 and AU79-1) showed moderate levels of genetic admixture (35.4% and 27.3%, respectively).

Sources:

  • NewsRx. Report Summarizes Agriculture Study Findings from Brazilian Agricultural Research Corporation (Analysis of the Genetic Diversity of the Soybean Rust Pathogen Phakopsora Pachyrhizi Reveals Two Major Evolutionary Lineages). Agriculture Week. June 12, 2025; p 407.
  • Fungal Genetics and Biology, 2025;179.
  • Fungal Genetics and Biology can be contacted at: Academic Press Inc Elsevier Science, 525 B St, Ste 1900, San Diego, CA 92101-4495, USA. (Elsevier - www.elsevier.com; Fungal Genetics and Biology - www.journals.elsevier.com/fungal-genetics-and-biology/)