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.
3. Progress Report:
Progress was made towards both objectives this year. Objective 1. In the previous year, we developed the methods to test interactions between several specific transcription factor proteins potentially implicated in seed development and DNA. This year, we decided to take advantage of new technologies for detection of protein-DNA interactions and redirect our efforts to perform more global studies to study protein-DNA interactions in seed storage protein gene promoters. We hope through this approach to refine our selection of transcription factor targets for protein composition improvement. Objective 2. From the ongoing screen for novel oil quality mutants, we have chosen the most promising lines with altered linolenic or oleic acid content, which are likely to lead us to genes, as yet unknown, that are involved in the determination and improvement of oil content. To identify the genes, we have advanced these lines by creating populations of plants for genetic mapping. This year we have also pilot-tested a new method for reverse genetic mutant identification (which still relies on the detection of DNA heteroduplexes, much like conventional TILLING). This alternative method is approximately one fourth of the cost of sequencing-based approaches, however has not yet been successfully applied to soybean.
1. New mutant alleles of fatty acid biosynthetic genes in soybean. For improved food and industrial oil quality, it is important to modify the composition of soybean oil. For example, reducing saturated fats in oils for food use, and increasing levels of oleic acid to improve the homogeneity and stability of soybean oil. The soybean mutant population at West Lafayette is a unique and valuable source of new alleles and genetic diversity to improve seed composition. To fully exploit this resource, ARS scientists in West Lafayette, Indiana are conducting an ongoing 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. This year the project team has focused efforts on creating populations to map the genes that underlie these traits. These genes represent new sources of variation for soybean seed fatty acid composition, and can be used by breeders in the near future to create soybean lines with improved fatty acid composition.