2011 Annual Report
1a.Objectives (from AD-416)
Objective 1: Identify and characterize genes or gene products that control metabolic expression of protein and oil accumulation during legume seed development.
Objective 2: Develop genomic resources to characterize the function of genes or gene products that mediate genetic variation in composition and allergenicity of seed storage proteins in soybean and comparable legumes.
1b.Approach (from AD-416)
The project uses molecular biological approaches to study the sequence and expression of genes that are required for soybean seed development. Genetic and biochemical approaches are used to study the interactions and function of gene products that are important for the accumulation of storage proteins or fatty acids in seeds. Genetic approaches are used to create mutant plants and characterize mutant plants in the TILLING population.
Constructs and systems to test protein-protein interactions in yeast for the transcription factors that we hypothesize influence soybean oil and protein content have been established this year. We have tested both protein-protein interactions, as well as protein DNA interactions for these factors. Protocols to perform chromatin immunoprecipitation (ChIP) on soybean seed DNA have also been tested to enable us to analyze DNA binding of these transcription factors in developing seeds.
After genetic characterization, well over 50 mutant plant lines with aberrant levels of one of the five major fatty acids present in seeds have been identified from the TILLING population. Genes known to be involved in seed fatty acid biosynthesis were sequenced to determine if the plants carried mutations in these known genes. As a result, 4 new alleles of a gene causing an increase in stearic acid, as well as a new allele of the gene that reduces levels of linolenic acid have been identified. Crosses to test the additivity of these traits were performed, and populations to map the location of other genes that have been identified in our screen were produced.
New mutant alleles of fatty acid biosynthetic genes in soybean. An improved fatty acid profile for soybean seeds is desirable for some food and industrial uses. For example, a reduction in linolenic acid for improved stability or reduction in the saturated stearic and palmitic acids for healthier oils. The soybean mutant population at West Lafayette is a source of new alleles and genetic diversity to improve seed composition. To fully exploit this resource, ARS scientists in West Lafayette, IN conducted a genetic screen for oil content to identify mutant plants that contain a higher or lower level of one of the five major fatty acids that compose soybean seeds. Characterization of some of these lines revealed that five of the lines in which seeds contain high levels of palmitic acid harbor mutations in a gene known to be involved in soybean seed oil biosynthesis. Four new mutations in a gene that causes seeds to contain high levels of stearic acid, and one new mutation in a gene that reduces levels of linolenic acid were also identified in this population. These new alleles can be used by soybean breeders alone or in combination with other mutations to further improve the seed fatty acid profile in a non-transgenic manner, and may help scientists understand how these enzymes work.
Hudson, K.A., Luo, S., Hagemann, N., Preuss, D. 2011. Changes in global gene expression in response to chemical and genetic perturbation of chromatin structure. Website: http://www.plosgenetics.org/search/simpleSearch.action?from=globalSimpleSearch&filterJournals=PLoSGenetics&query=Changes+in+global+gene+expression+in+response+to+chemical+and+genetic+perturbation+of+chromatin+structure&x=14&y=24