Research Project: Sclerotinia Initiative

Location: Sunflower and Plant Biology Research

2022 Annual Report

Objectives
Coordinate the development of a Sclerotinia initiative for expanded research to control this devastating disease which affects canola, sunflowers, soybeans, edible dry beans, lentils, peas and other crops. Research should be coordinated with interested ARS, state, and industry cooperators and administered through specific cooperative agreements. Planning workshops and annual meetings involving interested parties will be organized throughout the funding period.

Approach
Exotic and emerging plant diseases pose severe problems throughout the United States. Their increasing importance may be attributed to the introduction of pathogens into new geographic regions; modification of the environment that favor diseases; change in crop management practices; genetic shifts in the pathogen population; and other processes that may give them a competitive advantage.

Progress Report
This is the final report for this project which terminated in January 2021. See the report for the replacement project, 3060-21220-034-000D, “Improvement of Sclerotinia Disease Resistance and Management” for additional information. The National Sclerotinia Initiative, administered through the Edward T. Schafer Agricultural Research Center in Fargo, North Dakota, has used cooperative research to provide solutions to the debilitating effects of white mold disease on seven important crops: sunflower, soybean, dry beans, dry peas, lentils, and chickpeas. Cooperative projects were established each year with university, private research institution, and other Agricultural Research Service scientists. Research plans-of-work were requested for the fiscal year (FY) 22 funding cycle in December 2021. Almost $1.9 million in requests from 25 potential projects were received, with approximately $1.66 million available for distribution to selected plans-of-work. Proposals were reviewed and ranked by a scientific review panel. The Initiative Steering Committee met and awarded funds to 19 projects, spanning the research priority areas of Germplasm Resources & Translational Genomics, Pathogen Biology & Mechanisms of Resistance, and Disease Management & Crop Production. Over the past five years, the Initiative has awarded almost $6.2 million in funds for white mold research in the priority areas mentioned above. In-house research was also conducted as part of the Initiative. Over the past year, a third and final replication of inoculated field trials to evaluate Sclerotinia basal stalk rot resistance of approximately 100 early generation interspecific hybrids of cultivated sunflower with wild annual sunflower species was completed. A final replication of Sclerotinia head rot evaluations for an advanced backcross mapping population was completed to facilitate quantitative trait locus (QTL) mapping of resistance loci (genomic locations) that came from the wild perennial sunflower Helianthus maximiliani. QTL mapping was completed and identified 16 loci contributing to head rot resistance, 11 of which were derived from the H. maximiliani parent. Additionally, basal stalk rot resistance levels were evaluated for approximately 300 early generation and advanced sunflower test-cross hybrids to assess resistance potential for new inbred lines under development. These data are being used to select germplasm for further development or potential public release. Finally, grafting experiments were carried out to determine whether the oxalic acid tolerance trait associated with basal stalk rot resistance is conferred in root or shoot tissues. Preliminary results indicated that oxalic acid tolerance is conferred by the shoot.

Accomplishments
1. Identification of susceptibility to Sclerotinia root infection among plant species of the Asteraceae family. Basal stalk rot of sunflower results from root infection by the fungal pathogen Sclerotinia sclerotiorum. Although this fungus has a very broad host range, reports of S. sclerotiorum root infection of other plant species are rare and most such reports involve members of the Asteraceae plant family, which includes cultivated sunflower. To determine if root infection of Asteraceae species by S. sclerotiorum is more common than currently understood, ARS scientists in Fargo, North Dakota, and colleagues at North Dakota State University evaluated eight Asteraceae species for susceptibility to root infection. Results indicated that many plant species in the Asteraceae family are susceptible to root infection, expanding the known host range of this fungus and suggesting the importance of managing Asteraceae weeds to control S. sclerotiorum inoculum.

2. Soybean varieties developed with resistance to white mold disease. Soybean white mold disease (also known as soybean stem rot), which is caused by the fungus Sclerotinia sclerotiorum, reduces producer profits by almost $200 million annually across the United States. Because breeding resistant varieties is the most cost-effective strategy for the management of this disease, modern breeding technologies, including the use of molecular markers, have been used to combine white mold resistance traits with beneficial agronomic and seed quality traits in soybean. Researchers at Michigan State University, in a cooperative project with ARS reseachers in Fargo, North Dakota, have released two new soybean varieties, E12076T-03 and E15165T, with enhanced resistance to soybean white mold disease. Local seed companies have increased the seeds of both lines for commercial production, such that seeds would be available to farmers in 2023.

Review Publications
Underwood, W., Gilley, M., Misar, C.G., Gulya, T.J., Seiler, G.J., Markell, S.G. 2022. Multiple species of Asteraceae plants are susceptible to root infection by the necrotrophic fungal pathogen Sclerotinia sclerotiorum. Plant Disease. 106:1366-1373. https://doi.org/10.1094/PDIS-06-21-1314-RE.
Talukder, Z., Underwood, W., Misar, C.G., Seiler, G.J., Li, X., Cai, X., Qi, L. 2022. Genomic insights into Sclerotinia basal stalk rot resistance introgressed from wild Helianthus praecox into cultivated sunflower (Helianthus annuus L.). Frontiers in Plant Science. 13. Article 840954. https://doi.org/10.3389/fpls.2022.840954.
Talukder, M.I., Underwood, W., Misar, C., Seiler, G.J., Cai, X., Li, X., Qi, L. 2022. A quantitative genetic study of Sclerotinia head rot resistance introgressed from the wild perennial Helianthus maximiliani into cultivated sunflower (Helianthus annuus L.). International Journal of Molecular Sciences. 23(14). https://doi.org/10.3390/ijms23147727.
Fu, M., Pappu, H., Vandemark, G.J., Chen, W. 2022. Genome sequence of Sclerotinia sclerotiorum hypovirulence-associated DNA virus-1 found in the fungus Penicillium olsonii isolated from Washington state, USA. Microbiology Resource Announcements. 11(4). Article e00019-22. https://doi.org/10.1128/mra.00019-22.
Liang, W., Lu, Z., Duan, J., Jiang, D., Xie, J., Cheng, J., Fu, Y., Chen, T., Li, B., Yu, X., Chen, W., Lin, Y. 2021. A novel alphahypovirus that infects the fungal plant pathogen Sclerotinia sclerotiorum. Archives of Virology. 167:213-217. https://doi.org/10.1007/s00705-021-05315-4.
Gong, Y., Fu, Y., Xie, J., Li, B., Chen, T., Lin, Y., Chen, W., Jiang, D., Cheng, J. 2022. Sclerotinia sclerotiorum SsCut1 modulates virulence and cutinase activity. The Journal of Fungi. 8. Article 526. https://doi.org/10.3390/jof8050526.
Urrea, C.A., Smith, J.R., Porch, T.G. 2022. Registration of drought tolerant pinto SB-DT2 and small red SB-DT3 common bean germplasm from a shuttle breeding program between Nebraska and Puerto Rico. Journal of Plant Registrations. 16:400-409. https://doi.org/10.1002/plr2.20196.
Urrea, C.A., Pastor Corrales, M.A., Valentini, G., Xavier, L., Sanchez-Betancourt, E. 2021. Registration of the slow darkening pinto common bean cultivar ‘Wildcat’. Journal of Plant Registrations. 16:220-228. https://doi.org/10.1002/plr2.20198.
Urrea, C.A., Pastor Corrales, M.A., Valentini, G., Xavier, L.S., Sanchez-Betancourt, E. 2022. Registration of ‘White Pearl’ great northern common bean cultivar with upright plant architecture and high yield. Journal of Plant Registrations. 16(1):6-12. https://doi.org/10.1002/plr2.20167.
Mccaghey, M., Shao, D., Kurcezewski, J., Lindstrom, A., Ranjan, A., Whitham, S.A., Conley, S.P., Williams, B., Smith, D.L., Kabbage, M. 2021. Host-induced gene silencing of a Sclerotinia sclerotiorum oxaloacetate acetylhydrolase using bean pod mottle virus as a vehicle reduces disease on soybean. Frontiers in Plant Science. 12:677631. https://doi.org/10.3389/fpls.2021.677631.
Gambhir, N., Kamvar, Z.N., Higgins, R., Amaradasa, B.S., Everhart, S.E. 2021. Spontaneous and fungicide-induced genomic variation in Sclerotinia sclerotiorum. Phytopathology. 111:160-169. https://doi.org/10.1094/PHYTO-10-20-0471-FI.
Pedersen, C.J., Marzano, S.L. 2022. Characterization of transcriptional responses to genomovirus infection of the white mold fungus, Sclerotinia sclerotiorum. Viruses. 14(9). Article #1892. https://doi.org/10.3390/v14091892.