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Novel biocontrol agents for fungal pathogens in bread wheat (Triticum aestivum L.)

Posted on 19.01.2023 | Last Modified 08.07.2025
Lead Researcher (PI): Andriy Bilichak
Institution: Agriculture & Agri-Food Canada
Total WGRF Funding: $61,500
Co-Funders: Alberta Grains, Manitoba Crop Alliance, Saskatchewan Wheat Development Commission
Start Date: 2022
Project Length: 3 Years
Objectives:

To establish a catalogue of mycoviruses from the 300 rust isolates and correlate to the host virulence. To identify peptides with affinity to wheat flag leaves and urediniospores' surfaces using the phage display library.

Project Summary:

Wheat leaf rust and stripe rust, caused by the fungal pathogens Puccinia triticina (Pt) and Puccinia striiformis f. sp. tritici (Pst), respectively, pose a significant threat to wheat production globally. While control efforts have traditionally relied on resistant cultivars and fungicides, these pathogens evolve rapidly, demanding novel approaches. Mycoviruses – viruses that infect fungi – have emerged as potential tools for understanding fungal biology and developing biocontrol strategies. This study aimed to characterize the mycovirome of Pt and Pst isolates to assess viral diversity, abundance, and conservation and to explore their potential role in fungal virulence.

A total of 117 P. triticina isolates, representing 67 virulence phenotypes collected across Canada from 2012 to 2022, were analyzed through metatranscriptomic sequencing of infected wheat leaf samples. RNA sequencing generated over 7.2 billion reads, which were assembled into ~19 million contigs. Bioinformatic analysis identified 130 unique viral species from 25 viral families, including Totiviridae, Narnaviridae, and Mitoviridae, as well as unclassified viruses. The majority of contigs were associated with RNA-dependent RNA polymerases (RdRp), and Totiviridae was the most dominant viral family. All Pt isolates harbored multiple mycoviruses (4–38 per isolate), with distinct virus profiles often shared by isolates from the same or nearby regions.

Conservation of RdRp motifs A, B, and C was observed among several key viruses, suggesting functional integrity.

To validate the presence of these viruses, targeted PCR and sequencing confirmed Puccinia striiformis totivirus 1, Puccinia striiformis totivirus 3, and Puccinia narnavirus B in urediniospore RNA from selected isolates. A parallel analysis of published P. striiformis (Pst) transcriptome data identified an additional 92 viral species across nine families, reinforcing the finding that rust pathogens carry complex and diverse mycoviral communities.

This study presents the first comprehensive mycovirome profiling of P. triticina and provides new insights into P. striiformis. The widespread presence of mycoviruses, some of which have been previously linked to pathogenicity modulation in related species, suggests a potential influence on rust virulence and host interactions. These findings lay the groundwork for future functional studies, including the investigation of mycovirus-induced hypovirulence and the development of novel disease management strategies.