Soybean Genomic Libraries, TILLING, and Genetic Resources

Abstract

Soybean (Glycine max (L.) Merr.) is one of the most important crops worldwide, providing a sustainable source of protein and oil. Development and utilization of large-scale chemical mutagenesis in soybean is a promising strategy to develop new soybean genetic resources (germplasm) without the regulatory hurdles of genetic modification. Mutagenized soybean populations can be used with high throughput screening by Targeted Induced Local Lesions IN Genomes (TILLING) to identify mutations within genes of interest. By correlating an altered phenotype to the occurrence of mutations within a corresponding gene, protein function can be elucidated without the requirement of genetic transformation. Mutagenized soybean populations and their genomic libraries have been successfully applied to the identification of a soybean cyst nematode (SCN) resistance gene by correlating mutations within GmSHMT to a loss of SCN resistance, demonstrating that GmSHMT is the Rhg4 gene conferring SCN resistance. Additionally, by screening for mutations within genes involved in fatty acid biosynthesis, germplasm that accumulates high levels of oleic acid, stearic acid, or palmitic acid were discovered. Chemical mutagenesis as a forward genetics approach when coupled with TILLING as a reverse genetics approach has been proven to be a valuable tool for soybean researchers in the discovery and development of agronomically important traits.