Location: Sugarbeet Research
2023 Annual Report
Objectives
Objective 1. Develop new strategies, identify molecular markers, and release germplasm for the genetic enhancement of pest and disease resistance in sugarbeet.
Sub-objective 1A: Identify new genetic sources for improving sugarbeet resistance to Cercospora leaf spot and sugarbeet root maggot.
Sub-objective 1B: Conduct genetic mapping and marker development for genes conferring sugarbeet root maggot resistance.
Sub-objective 1C: Develop new pre-breeding germplasm with improved resistance to Cercospora leaf spot and sugarbeet root maggot.
Objective 2. Develop strategies to limit sucrose losses due to disease, such as Cercospora leaf spot, and postharvest metabolism through a fundamental understanding of pathogen diversity, pathogen/host/environment interactions, and storage physiology in sugarbeet.
Sub-objective 1C: Develop new pre-breeding germplasm with improved resistance to Cercospora leaf spot and sugarbeet root maggot.
Sub-objective 2B: Identify genomic loci in the C. beticola genome associated with adaptation to management practices including fungicides and new tolerant sugarbeet varieties.
Sub-objective 2C: Identify rhizomania resistance-breaking variants of Beet necrotic yellow vein virus using high-throughput sequencing technologies.
Sub-objective 2D: Investigate virus-host interactions to characterize virulence factors and host-responsive elements that can be used to develop new tools for rhizomania disease management.
Sub-objective 2E: Identify and characterize genes and metabolic pathways responsible for sucrose loss and quality deterioration during storage and determine genetic and environmental factors that regulate them.
Sub-objective 2F: Identify and characterize sugarbeet storage pathogens.
Sub-objective 2G: Assess the effect of in-season fungicides on soil communities of postharvest pathogens in the sugarbeet rhizosphere.
Objective 3. Develop integrative agronomic tools and strategies for managing the emerging threat of herbicide-resistant weeds that threaten sugarbeet production in the United States.
Approach
The U.S. sugarbeet industry is valued at $1.7 billion and ensures a domestic supply of a staple in the American diet. Productivity and sustainability of the industry, however, is imperiled by the diseases Cercospora leaf spot (CLS) and rhizomania, the sugarbeet root maggot (SBRM), herbicide-resistant weeds, and storage deterioration. Collectively, these agricultural challenges cost the industry more than $350 million annually. Losses to these challenges are expected to intensify in future years since the pathogens responsible for CLS and rhizomania are increasingly tolerant to contemporary and conventional chemical and genetic controls, pesticides for SBRM control are increasingly use-restricted, herbicide tolerance in weed species and populations is growing, and climate change is fueling storage losses. New management strategies, therefore, are needed to maintain industry productivity and sustainability. However, the development of new management strategies requires a greater understanding of the fundamental biology underlying these challenges and new genetic tools. Research is proposed to generate the knowledge and tools needed to reduce losses to CLS, rhizomania, SBRM, herbicide-resistant weeds and storage deterioration by (1) identifying new sources of genetic resistance for CLS and SBRM control, (2) developing new CLS and SBRM resistant germplasm, (3) developing molecular markers for CLS and SBRM genetic resistance, (4) generating new understanding of how pathogens responsible for CLS and rhizomania overcome host genetic resistance and pesticide toxicity, (5) determining and characterizing population diversity and gene flow for CLS- and rhizomania-causing pathogens, (6) identifying and functionally characterizing genes responsible for postharvest sucrose loss and quality deterioration, (7) identifying and characterizing the microbes causing storage diseases, and (8) determining the effect of in-season fungicides on postharvest pathogen diversity. Success in this research will provide knowledge and tools to reduce losses to CLS, rhizomania, SBRM, herbicide resistant weeds, and storage deterioration for improved productivity and sustainability of the sugarbeet industry.
Progress Report
This Project was initiated in April of 2023 and replaces Project 3060-21000-044-000D. See that project’s report for progress made earlier in the reporting year.
Research proposed for all subobjectives under Objectives 1 and 2 of the new Project Plan have been initiated. Under Objective 1, a set of 602 Beta maritima accessions along with 1,304 cultivated beet lines were genotyped to identify a core collection of Beta maritima with high levels of genetic diversity relative to cultivated sugarbeet. For Cercospora leaf spot resistance evaluation, B. maritima accessions were planted in disease nurseries at three locations; for identifying new sources of resistance to the sugarbeet root maggot, B. maritima accessions were planted in field plots near St. Thomas, North Dakota. Additionally, the development of a mapping population for genetically localizing sugarbeet root maggot resistance genes and marker development was initiated. Under Objective 2, the development of genomic resources for Cercospora beticola is underway with pathogen inoculation experiments performed on sugarbeet and samples collected from different infection time points. These infected samples will be used to characterize genes expressed throughout the disease interaction. Fungal tissue cultures from isolates collected from globally diverse sugar beet producing regions have been started, with DNA extractions to begin shortly for whole genome sequencing. DNA from C. beticola isolates collected in 2021 from the Red River Valley has been isolated and whole genome sequencing is underway to identify mutations associated with adaptation to management practices that include the use of varieties with new resistance genes and fungicide applications. Efforts to identify rhizomania resistance-breaking variants of Beet necrotic yellow vein virus (BNYVV) have begun with the collection of rhizomania-infested soil and sugarbeet samples from California, Idaho, Minnesota, and North Dakota sugarbeet fields. Studies to investigate virus-host interactions were initiated by inoculating roots of sugarbeet seedlings with regional strains of BNYVV and extracting RNA for sequencing. Research into the causes of postharvest storage losses advanced with the identification of genes that potentially participate and regulate postharvest sucrose loss due to root respiration and raffinose accumulation based on changes in their postharvest expression. Additionally, the identification of organisms responsible for storage losses progressed with the isolation and culture of pathogens from diseased roots that were collected from outdoor storage piles during the 2022-2023 processing campaign. These pathogens will be identified in coming months.
Accomplishments
