Sexual recombination in cereal rust fungi: Knowns and unknowns of pathogen evolution and adaptation
Year: 2025
Type: article
Abstract: Why do sex and cereal rust fungi matter?Cereal rust fungi, encompassing several species of Puccinia, pose a significant threat to global food security.Notable cereal rust pathogens on wheat include P. graminis f. sp.tritici (stem or black rust, Pgt), P. striiformis f. sp.tritici (stripe or yellow rust, Pst), and P. triticina (leaf or brown rust, Pt), while P. hordei (Ph) affects barley and P. coronata f. sp.avenae (Pca) infects oats [1].The agricultural importance of rust fungi is deeply rooted in history, with archaeological evidence dating the presence of stem rust to over 3,300 years ago [2].Ancient farmers sought divine intervention against rust fungi, with Romans establishing the deity Robigus to ward off rust-related disasters [3].By the 17th century, farmers had recognized that severe cereal rust epidemics occurred near barberry shrubs (Berberis species).Despite barberry's value as a medicinal plant, source of dyes, and popular hedging shrub, this observation led to the first barberry eradication laws in Rouen, France in 1660 [4].In 1866, Anton de Bary proved that P. graminis required both wheat and barberry to complete its life cycle [5].This discovery prompted widespread barberry eradication programs, including Denmark (1903) [6] and the United States of America (1918) [4].However, the role of the sexual host in generating novel pathogen strains was not recognized until Craigie's 1927 discovery of the function of the sexual structures in rust fungi [7].Subsequent studies confirmed that rust strains with different patterns of infection on wheat varieties could arise through strain hybridization during sexual reproduction on the sexual host [8].This understanding of the sexual host's function in generating novel pathogen variability became critical for cereal rust management strategies.Subsequent barberry eradication campaigns not only reduced disease incidence but also stabilized pathogen populations and delayed epidemic onsets [9].However, complete eradication of the sexual host is not always feasible or environmentally desirable, especially in areas where they have significant ecological importance [10].The ongoing challenge of managing cereal rusts highlights the significance of their complex biology, particularly their sexual reproduction cycle.This evolving knowledge of rust biology has shaped management strategies and emphasizes the need for continued research to address current and future challenges in cereal rust control. When do cereal rusts have one or two nuclei?Cereal rust fungi exhibit a complex life cycle characterized by alternating nuclear states: haploid (n), dikaryotic (n+n), and diploid (2n) phases, occurring across both sexual and asexual life-stages on two botanically distinct host plants (Fig 1) [11].
Source: PLoS Pathogens
Institutions: Aarhus University, Australian National University
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $3,043
Funder: Villum Fonden
Awards: G1658606713, G5408966463
OpenAlex ID: W4407131920