A New Locus for Early Maturity in Soybean

The genetic model for maturity in soybean [Glycine max (L.) Merr.] is a series of near-isogenic lines, but they do not span the natural variation for early maturity. The objectives of this study were to determine if a single gene in OT98-17 controls early maturity and if this is a new locus. A cross was made between 'Maple Presto' and OT98-17, an early-maturing Maple Presto-derived backcross line. A total of 201 F 3 progeny rows from this population and Maple Presto were grown at Ottawa, ON, in 1999. In 2000, F(4) progeny rows were grown and 150 late-maturing and 51 early-maturing families were observed to fit a 3:1 ratio (n = 201, X(2) = 0.01, P = 0.90). The early-maturing allele was transferred to a 'Harosoy' background, and isolines were grown from 2002 to 2006 at Ottawa, ON. The isolines were 9 and 6 d earlier maturing in Maple Presto and Harosoy backgrounds, respectively. To determine the independence of this locus, simple sequence repeat molecular markers were used to identify three candidate regions. The gene E8 specifically mapped to linkage group C1 between Sat 404 and Satt136. No other maturity gene has been mapped to this region. The two other candidate regions were both related to maturity quantitative trait loci on molecular linkage group L and may be inadvertently selected along with early maturity. The gene symbol E8e8 has been assigned by the Soybean Genetics Committee. E8E8 results in later maturity and e8e8 results in early maturity. The earliest Harosoy maturity isoline is now rated as maturity group 000.