Genome-Wide Association Mapping for Traits Relevant to Sclerotia Production by the Necrotrophic Fungal Pathogen <i>Sclerotinia sclerotiorum</i>

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 that can remain viable in soil for many years, presenting a major challenge for disease management. Relatively little is currently known about the genes and molecular processes governing sclerotial development, survival, 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: (i) time to sclerotia production and (ii) 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, and 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. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .