Occurrence and characterization of Puccinia triticina in Zimbabwe

Abstract

Wheat leaf rust caused by Puccinia triticina (Pt) is an important disease of bread wheat in Zimbabwe. This study was carried out to determine the distribution, avirulence/virulence profile(s) and genotypic variation among isolates of the pathogen. In total, 104 single-pustule isolates were established from infected wheat samples that were collected from the main wheat production regions in Zimbabwe in surveys conducted from 2019 to 2021. Phenotyping of the isolates on a set of 46 differential and additional wheat lines revealed a single Pt race, MCDS. For genotypic assessment, 48 Pt isolates, including eight South African races, were genotyped with 19 microsatellite markers. Using the Bayesian model, isolates were subdivided into three clusters in both a DARwin neighbour-joining tree and STRUCTURE analysis. The results confirmed a high genetic similarity between the Zimbabwean Pt isolates and the South African races MCDS, MCPS and MFPS. Furthermore, Pt isolates from Zimbabwe were clonal, which was in accordance with all 104 isolates that typed to race MCDS.

Résumé

La rouille des feuilles du blé causée par Puccinia triticina (Pt) est une maladie importante du blé panifiable au Zimbabwe. Cette étude a été réalisée pour déterminer la distribution, le(s) profil(s) d’avirulence/virulence et la variation génotypique parmi les isolats de l’agent pathogène. Au total, 104 isolats à pustule unique ont été établis à partir d’échantillons de blé infectés qui ont été collectés dans les principales régions de production de blé du Zimbabwe lors d’enquêtes menées entre 2019 et 2021. Le phénotypage des isolats sur un ensemble de 46 lignées de blé différentielles et supplémentaires a révélé une seule race Pt, MCDS. Pour l’évaluation génotypique, 48 isolats de Pt, dont huit races sud-africaines, ont été génotypés avec 19 marqueurs microsatellites. En utilisant le modèle bayésien, les isolats ont été subdivisés en trois groupes dans un arbre DARwin avec jointure de voisinage et dans l’analyse STRUCTURE. Les résultats ont confirmé une grande similarité génétique entre les isolats de Pt du Zimbabwe et les races sud-africaines MCDS, MCPS et MFPS. En outre, les isolats de Pt du Zimbabwe étaient clonaux, ce qui correspondait à l’ensemble des 104 isolats qui ont été typés pour la race MCDS.

Keywords:

• Leaf rust
• microsatellite markers
• surveillance
• Triticum aestivum

Mots-clés:

• Marqueurs microsatellites
• rouille foliaire
• surveillance
• Triticum aestivum

Acknowledgments

Wheat producers in Zimbabwe for allowing access to their fields and the establishment of wheat trial plots.

Author contributions

All authors contributed to the conception and design of the study. N. Chiuraise conducted annual rust surveys and rust pathotyping on standard differential lines and completed the microsatellite analysis. N. Chiuraise wrote the first draft of the manuscript and all authors read, revised and approved submission of the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Declarations

We hereby declare that our submission complies with the ethical responsibilities and standards of the Canadian Journal of Plant Pathology, as well as those of the UFS.

Supplementary material

Supplemental data for this article can be accessed online here: https://doi.org/10.1080/07060661.2024.2356192.

Additional information

Funding

The National Research Foundation [SARChI chair UID 8464] and Seed-Co Ltd is thanked for funding.