Uncovering A New Allelic Variation j-x Previously Presumed to be a Linked Gene, E6, In Soybean (Glycine max)

Soybean grown in latitudes of ~20˚ or lower, produce reduced grain yield due to the shorter days within those latitudes. One way to overcome this limitation is by growing varieties carrying the long juvenile (LJ) trait, identified as the J gene, Glyma.04g050200. The LJ trait allows the plant to remain in the vegetative state for a much longer period, delays flowering and produces higher yields. In this study, we sought to determine if E6 and J are the same locus or linked loci as they were mapped to the same location on Chromosome 4. PCR and sequencing reactions of contrasting soybean lines identified the presence of a Ty1-copia retrotransposon within the 4th exon of the J gene in soybean line ”Paranagoiana”, where the E6 locus was first mapped. This was confirmed to impact the mRNA of the gene through further cDNA sequencing of Glyma.04g050200. Our results show that the previously identified soybean maturity locus, E6, does not exist, and that the LJ trait seen in Paranagoiana is due to a new variation in J which we deemed j-x.