Location:2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Evaluate, characterize, and utilize available sugarbeet genetic resources and ascertain the diversity (genetic, proteomic, morphological, and pathogenic) within and among sugarbeet and sugarbeet pathogen populations to fulfill the objectives below. This objective is an important part of the ARS NPGS Beta germplasm collection, which is available to public and private breeders and geneticists. Sub-objective 1a: Determine the spatial scale of genetic differentiation among populations of B. nana. Objective 2: Characterize the interaction of major sugarbeet pathogens (esp. Beet necrotic yellow vein virus, Cercospora beticola, Rhizoctonia solani, and Fusarium oxysporum) with sugarbeet. Sub-Objective 2a: Apply proteomics protocols to understand Beet necrotic yellow vein virus-sugar beet interactions. Sub-Objective 2b: Using comparative proteomics, determine the degree of conservation of defense response against a variety of Fusarium spp. Sub-Objective 2c: Determine role of ubiquitination and the proteosome pathway in activation of plant defense. Objective 3: Develop and distribute enhanced germplasm with novel stress resistance genes.
1b. Approach (from AD-416)
Objective 1 A multidisciplinary approach combining traditional genetics, molecular biology, and biochemistry will characterize variation among sugarbeet wild relatives and cultivated beets. Understanding the diversity within the NPGS Beta PI collection is necessary to both intelligently manage and utilize the germplasm stored in this collection. Understanding of the diversity contained in our commercial lines is necessary to most effectively introduce new diversity into them. Understanding the genetic variability of pathogen populations is extremely important to maintaining durable host plant resistance. The same classical and molecular tools will be used to gain the knowledge of genetic diversity in the pathogens, which is critical for selecting the number and pathotype of organisms to use in resistance screening. Objective 2 This multidisciplinary approach combining traditional genetics, molecular biology, and biochemistry will be used for identification of key genes or proteins involved in the sugar beet pathogen interaction. Characterization using varied techniques provides a better understanding of plant defense against disease and identifies candidate genes and novel sources of resistance to move into sugar beet germplasm. Furthermore, this greater knowledge of sugar beet pathogen interaction opens up avenues for creating novel selection tools, including exploitation of polymorphisms and use of biomarkers. The same analyses can be used to understand and better manage pathogens of sugar beet, creating novel, more effective disease control strategies. Objective 3 The basis of the breeding program is the formation of long range breeding populations through the introgression of resistant germplasm from “exotic” sources of the primary Beta germplasm pool (Beta vulgaris ssp. maritima, fodder beet, table beet, Swiss chard, foreign sugar beet landraces from the PI collection, etc.). This breeding scheme provides great flexibility to accommodate the genetic background of the germplasm and the disease resistances being chosen. The development of breeding populations will be accomplished using methods that produce genetically defined sub populations, which are useful for resistance gene mapping, marker development, exploring sugarbeet-pathogen interactions, and gene discovery.
3. Progress Report
This is the FY11 report for Project 5402-21220-007-00D. Progress was made in addressing the Problem Statements 3A, Genetic Theory and Methods of Crop Improvement and 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties and of the NP301 Action Plan. We made significant progress in ascertaining diversity in sugarbeet genetic resources through screening for rhizoctonia root rot and beet curly top virus in field nurseries (Objective 1). Also significant improvements to the rhizoctonia nursery screening methodology were made. Using these results, progress has been made in developing and distributing enhanced germplasm with novel stress resistance genes (Objective 3). Breeding populations with resistance to sugarbeet cyst nematode, cercospora leaf spot, fusarium yellows, and rhizoctonia root rot have been advanced. Four rhizomania and rhizoctonia resistant germplasms were registered in the Journal of Plant Registration. One joint release with USDA-ARS Fargo with resistance to cercospora leaf spot and sugarbeet root maggot also was registered in the Journal of Plant Registrations. Four more germplasm with resistance to rhizomania and cercospora leaf spot are being prepared for ARS release. Progress has been made in understanding the interaction of fusarium yellows (FOB), a fungal disease, with sugar beet (Objective 2). Fusarium yellows of sugar beet can lead to significant reductions in yield. Genetic resistance and sound cultural practices (primarily water management) are the only reliable management tools. Isolates of the fungus causing FOB are categorized by their ability to cause disease on specific crop plants, vegetative compatibility grouping (VCG), and genetic relationships. Sugar beet often is grown in rotation with other crops including dry edible bean and onion, on which FOB may cause significant diseases. Modest information is available regarding how crop rotation can influence diversity of local populations of FOB in particular production regions. We have shown cross pathogenicity with some FOB isolates being able to attack both onion and sugar beet. The VCG testing indicated that the FOB population is very diverse with many origins and most likely cannot be classified into distinct races on this basis. How FOB causes Fusarium yellow is mostly unknown. The DNA code of known compounds produced by similar fungi has been used to screen the DNA from the strains of fungus that cause Fusarium yellows. Some genes have been indentified and will be checked to see if they are active in causing disease. Additionally, the second year of a three year field study to examine the influence of air temperature, soil temperature, soil moisture, and air moisture to disease severity and onset of diseases has begun. Growth chamber experiments corresponding to the field experiments also have been initiated to more closely study how air temperature contributes to disease severity.
Biancardi, E., Mcgrath, J.M., Panella, L.W., Lewellen, R.T., Stevanato, P. 2010. Sugar Beet. Chapter 6. In J. Bradshow (ed.) Tuber and root crops. Handbook of Plant Breeding, vol. 7. Springer Science + Business Media, LLC, New York, NY. 173-219.