Location: Northwest Irrigation and Soils Research
Project Number: 2054-21220-005-000-D
Project Type: In-House Appropriated
Start Date: Jan 24, 2018
End Date: Jan 23, 2023
Objective:
1. Develop genetic markers that will allow for marker-assisted breeding; develop superior sugar beet germplasm with priority traits, such as high sucrose and resistance to various diseases; and release improved breeding materials, including doubled haploid lines, inbred lines, and genetic mapping populations.
1.1. Develop elite germplasm with curly top, Rhizoctonia crown and root rot (RCRR), Cercospora leaf spot (CLS), and storage rot resistance, and high sucrose and low impurities. (Eujayl, Strausbaugh)
1.2. Conduct whole genome sequencing of elite germplasm lines for genetic variation analysis for RCRR resistance. (Eujayl, Strausbaugh)
1.3. Establish a large complement of single nucleotide polymorphism (SNP) markers for genotyping mapping populations and germplasm for curly top and RCRR resistance. (Eujayl, Strausbaugh)
2. Dissect disease development pathways and host-pathogen interactions, and design improved disease management strategies and screening procedures in sugar beet.
2.1. Investigate the interaction between the most common Leuconostoc van Tiegham haplotypes and the various genetic subgroups of R. solani. (Strausbaugh)
2.2. Investigate the use of RNA interference (RNAi) for the control of Beet curly top virus (BCTV). (Strausbaugh, Eujayl)
2.3. Develop additional management strategies for curly top and pest control in sugar beet. (Strausbaugh)
Approach:
The proposed research is a coordinated cooperative effort between USDA-ARS, university scientists, and industry partners which will improve sucrose yield in sugar beet production. Elite sugar beet germplasm will be developed to increase sucrose content, while reducing impurities and improving disease resistance and management options for Beet curly top virus (BCTV), Rhizoctonia solani, and storage rot fungi. The first objective is non-hypothesis research focused on improving or identifying novel traits of interest, releasing elite germplasm with these traits, and sequencing lines to map and develop markers for these traits. Genetic markers will allow for marker-assisted breeding and release of superior sugar beet germplasm. Backcrossing, mass selection, and recurrent selection will be used to produce populations and lines with disease resistance, low impurities, and high sucrose content. Doubled haploid lines from this germplasm will be used to produce hybrids and segregating populations for genetic mapping. Whole genome sequencing will be conducted using PacBio technology and optical mapping. This effort will be complemented with gene expression profiling via RNA-Seq and Iso-Seq to identify differentially expressed genes caused by R. solani infection. A large complement of single nucleotide polymorphism (SNP) markers for genotyping mapping populations and germplasm for curly top and Rhizoctonia crown and root rot resistance will be developed. If additional sources of high sucrose or disease resistance are needed, additional high sucrose parental lines and plant introduction accessions will be screened. The second objective is hypothesis driven research which advances our knowledge of disease development and interactions to improve disease management strategies and screening procedures in sugar beet production. The interaction between Leuconostoc and R. solani will be investigated, since Leuconostoc haplotypes will possibility vary in their ability to create more root rot through a synergistic interaction with genetic subgroups of R. solani. Root inoculations in field studies will be conducted with bacterial isolates representing the predominant haplotypes for L. mensenteroides and L. pseudomesenteroides and R. solani isolates representative of the diversity present in anastomosis groups found in sugar beet. Five weeks after inoculation, rotted tissue will be measured and the pH associated with that tissue will be established. Isolations from the leading edge of the rot from randomly selected roots will be conducted to complete Koch’s postulates. Based on the results from the interaction studies, fungal-bacterial combinations exhibiting the synergistic interaction will be evaluated further through inhibition and enzyme assays. To improve management options for BCTV, the use of RNA interference (RNAi) and foliar insecticides will be investigated. If RNAi proves successful, RNAi will also be investigated for the control of R. solani.
