The Tgm9-Induced Indexed Insertional Mutant Collection to Conduct Community-Based Reverse Genetic Studies in Soybean

Until now, functional analyses of soybean genes have been very arduous because of the lack of a rapid transformation procedure. Recently identified the active endogenous type II transposable element, Tgm9, excises from insertion sites and restores wild-type phenotypes. Thus, this element provides a great promise in cloning soybean genes bypassing challenges associated with soybean transformation.  By applying a novel high-throughput technology, we determined Tgm9-insertion sites in 5,184 lines. These Tgm9 insertions are found in all twenty soybean chromosomes showing preferential re-insertion into gene-rich chromosomal arms as compared to gene-poor centromeric regions. Among the 5,184 mutants, 1,542 represent potential Tgm9-induced gene-disruption mutants at a rate of 50 to 106 per chromosome. Considering that only 16% of the soybean genome contains genes, this study establishes that a Tgm9 mutagenesis population is enriched for potential gene-disruption mutants making Tgm9 an important resource for functional analysis of soybean genes.