Identifying Genes Important for Determining Lateral Branch Angle in Soybean Using a Fast Neutron Mutagenized Population

Soybean (Glycine max) genetic diversity has been reduced due to domestication and selective breeding. We used a fast neutron (FN) mutagenized population of soybean in background ‘M92-220’ and identified mutants that were altered in qualitative and quantitative traits. Changes in shoot architecture and particularly those that display differences in the angle of lateral branching are of interest since altering the shoot branching angle may influence light perception as well as harvest index, resulting in increased yield. We identified several unique mutant lines in the FN population that showed differences in the lateral branch angle. Our aim is to identify the loci responsible for the different phenotypes by mapping and eventually cloning the underlying gene(s). We are using a complementary approach of bulk segregant whole genome sequencing and array Comparative Genomics Hybridization to identify regions of the genome controlling these mutant phenotypes. Using this approach we have identified candidate genes in the mapped regions that may be important for controlling lateral branch angle. Experiments are underway to functionally characterize the candidate genes as well as to determine the effect of lateral branch angle on overall yield of soybean. Additionally, a set of diverse lines from the USDA Soybean Germplasm Collection has been genotyped with a 50K SNP assay and phenotyped for branch angle. GWAS will be conducted on the combined datasets and the results will be presented.