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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Research Project #434160

Research Project: Development of Elite Sugar Beet Germplasm Enhanced for Disease Resistance and Novel Disease Management Options for Improved Yield

Location: Northwest Irrigation and Soils Research

2018 Annual Report


Objectives
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.


Progress Report
This report documents progress for project 2054-21220-005-00D, which started January 2018 and continues research from project 2054-21220-004-00D, "Improved Sugar Beet Germplasm and Innovative Disease Management Approaches to Increase Yield and Reduce Product Losses." Novel germplasm lines and populations with multiple traits are under development. Specifically, hybrids were tested for incorporation of the non-bolting trait into high sucrose parental lines. Research was initiated to identify DNA markers for the new non-bolting mutant line. Development of a mapping population was initiated to allow for mapping the non-bolting trait in public germplasm. Gene pyramiding for curly top (using different resistant parental lines) has been started using the dataset of differentially expressed genes. Similarly, hybridization of Rhizoctonia resistant doubled haploid lines was initiated. Field plots have been planted to study the interaction between the bacteria Leuconstoc and Rhizoctonia solani and to evaluate management options for curly top. An initial greenhouse study to investigate the use of RNA interference for the control of curly top has been completed. Using RNA generated from the coat protein region of the Beet curly top virus genome did not elicit enough response to be useful. Thus, RNA generated from other regions of the Beet curly top virus genome will be investigated.


Accomplishments


Review Publications
Strausbaugh, C.A., Eujayl, I.A. 2018. Influence of Beet necrotic yellow vein virus and freezing temperatures on sugar beet roots in storage. Plant Disease. 102:932-937. https://doi.org/10.1094/PDIS-10-17-1575-RE.
Strausbaugh, C.A. 2018. Commercial sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2016. Plant Disease Management Reports. 12:CF004.
Strausbaugh, C.A. 2018. Experimental sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2016. Plant Disease Management Reports. 12:CF003.
Strausbaugh, C.A., Fenwick, A.L. 2018. Beet curly top resistance in USDA-ARS Ft. Collins germplasm, 2017. Plant Disease Management Reports. 12:CF002. https://eprints.nwisrl.ars.usda.gov/id/eprint/1654.
Strausbaugh, C.A., Hellier, B.C. 2018. Beet curly top resistance in USDA-ARS plant introduction lines, 2017. Plant Disease Management Reports. 12:CF001.
Strausbaugh, C.A., Wenninger, E. 2018. Foliar insecticides for the control of curly top in Idaho sugar beet, 2017. Plant Disease Management Reports. 12:CF082.