Location: Sugarbeet and Bean Research2008 Annual Report
1a. Objectives (from AD-416)
1) Enhance and release sugarbeet germplasm that represents substantially improved populations enriched for novel genetic combinations for the unique Eastern U.S. growing regions; 2) Develop and exploit sugarbeet and other species nucleotide sequence information for marker-assisted gene discovery, including development and release of simple sequence repeats (SSR) and single nucleotide polymorphism (SNP) markers; and 3) Develop simplified phenotyping assays for priority biotic and abiotic stress resistance and early season development suitable for molecular analyses.
1b. Approach (from AD-416)
Traditional sugarbeet population improvement approaches will be deployed for open pollinated, self-incompatible germplasm for release to industry. Production of improved populations will follow from mother root selection under field, greenhouse, or laboratory conditions of one or more germplasm sources, followed by random inter-mating, and harvest of seed from either individual plants, genetically related individuals, or as an entire population. Selfed families will be created from self-fertile materials generated to dissect the genetic control of high priority disease resistances. A program of phenotypic selection is followed by selecting mother roots from field nurseries, selfing these hybrids in the greenhouse, and applying molecular markers. Molecular markers will be developed from sugar beet nucleotide sequences, located to one of the nine beet chromosomes, and compared with segregation of disease and agronomic traits to identify genetic control. Mapped molecular markers will also be used to integrate sugar beet Bacterial Artificial Clones on the genetic linkage map for eventual isolation of specific genes that control agronomic and disease traits. Transcript profiling will be employed for gene discovery, however these tools are new for germplasm enhancement and their use has not been well explored. Examining transcript of profiles during sugar beet development, and during abiotic and biotic stress will allow deduction of important physiological and biochemical clues to the plant responses to stress and development that can be used towards more rigorous application in germplasm enhancement. The prevalence of different sugar beet pathogens in the Michigan agro-ecosystem will be ascertained, and used to develop high priority targets for transcript profiling. Differential disease reaction to Fusarium oxysporum, for instance, as an example of a newly discovered pathogen for Michigan, will form the basis for transcript profiling experiments that will better characterize the disease infection process and assist in identifying targets of opportunity for breeding intervention. Populations and their progeny showing good agronomic and disease performance will be folded into the general agronomic and disease nursery evaluations, and released to industry as enhanced germplasm.
3. Progress Report
Germplasm enhancement activities are underway with individual field and greenhouse trials in Michigan encompassing agronomic evaluation, selection for resistance to Cercospora leaf spot, Fusarium yellows, and Rhizoctonia seedling and root diseases, assessment and selection for sugar beet cyst nematode resistance, and assessment of stand establishment potential. Over 900 distinct entries, not including those submitted for the official leaf spot nursery, are being evaluated. From these trials, individuals with superior characteristics will be selected after evaluation of their performance during the current growing season. Over 100 newly mapped SSRs have been placed on the ARS genetic map of sugar beet, and these are currently being summarized for release and publication. A comprehensive survey of sugarbeet disease-causing fungal pathogens present in the Great Lakes growing areas is continuing--the first survey in over 25 years. Results confirm presence of known pathogens and suggest involvement of others whose precise roles are being ascertained. This progress addresses NP301 Component 2, Crop Informatics, Genomics, and Genetic Analyses, Problem Statement 2C, Genetic Analyses and Mapping of Important Traits by providing a genetic map and markers for sugar beet and identifies candidate genes for genetic analysis of seedling vigor. It also addresses NP 301, Component 3, Genetic Improvement of Crops, Problem Statement 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties by producing and evaluating breeding populations to ascertain their suitability for release as enhanced germplasm with desired traits for increased sugar beet productivity.
5. Significant Activities that Support Special Target Populations