Genome-wide association mapping for traits relevant to sclerotia production by the necrotrophic fungal pathogen Sclerotinia sclerotiorum

Authors: Underwood, William

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The fungus Sclerotinia sclerotiorum can infect a large number of plant species and causes economic damage on many important crop plants including sunflowers, canola, soybeans, and dry edible beans. Management of diseases caused by this fungus is challenging for farmers because the fungus produces dormant resting structures, referred to as sclerotia, that contaminate agricultural fields and maintain the capacity to germinate and infect crop plants for over a decade. The details of how sclerotia production is regulated, factors impacting longevity and survival of sclerotia, and how sclerotia initiate germination are poorly understood. In this study, a large collection of S. sclerotiorum isolates collected from different host plants throughout the United States was evaluated for growth and development traits, including traits related to production of sclerotia. Data from these evaluations were used for genetic mapping to identify candidate genes involved in regulating sclerotial development. These efforts identified seven genomic regions associated with timing of sclerotia production and three regions associated with number of sclerotia produced. These results will improve our understanding of how this fungus produces long-lived, dormant resting structures and may lead to new strategies to improve disease management and reduce crop losses to this destructive pathogen.

Technical Abstract: The fungal pathogen Sclerotinia sclerotiorum causes substantial economic damage to agriculture in the United States and globally. This pathogen can infect an unusually broad range of plant hosts, including many economically important crop species. S. sclerotiorum produces dormant resting structures referred to as sclerotia at the end of its disease cycle which can remain viable in soil for many years, presenting a major challenge for disease management. Relatively little is currently known about genes and molecular processes governing sclerotial development, survival and longevity, and subsequent germination. Isolates of S. sclerotiorum exhibit considerable variation in morphological and developmental traits, including traits relating to production of sclerotia. In this study, growth and development traits were evaluated for a collection of 227 S. sclerotiorum isolates obtained from 26 different host plants across 27 U.S. states. Genome-wide association studies were carried out for the traits time to sclerotia production and number of sclerotia produced. These studies identified seven marker-trait associations for time to sclerotia production and three associations for number of sclerotia produced. A single gene previously described to impact sclerotial development was found near a significant association for time to sclerotia production, while several other genes with predicted functions related to processes implicated in sclerotial development were also located near associated markers. Further studies of these candidate genes may provide new information about the processes governing sclerotial development in this destructive fungal pathogen.