A new soybean maturity and photoperiod-sensitivity locus linked to E1 and T

An association between early maturity and tawny pubescence has been observe d in short-season soybean [Glycine mar (L.) Merr.]. The objectives of this study were to determine if a single locus controls early maturity; and if t here is a new locus linked to E1 and T or, alternatively, a third allele at the E1 locus. A cross was made between 'Harosoy' isolines OT89-5 (e3e3 e4e 4) and OT94-47. PI 196529 was the donor of early maturity in the backcrossi ng program which developed OT94-47. A total of 229 F-2 plants and the paren ts were grown under 20-h photoperiods produced by incandescent lamps. OT94- 47 flowered in 43 +/- 1.4 d, OT89-5 flowered later in 57 +/- 4.2 d, and the F2 population fit a 3 late: 1 early flowering ratio. Early-flowering F2 pl ants produced F-3 families that flowered similarly to OT94-47. Later-flower ing F2 plants either segregated for flowering date or flowered similarly to OT89-5. To test for allelism with E1 and linkage with T, a cross was made between OT93-26 (E1E1 e3e3 e4e4 TT) and OT94-47. F2 plants were classified as parental types or intermediate and equivalent to OT89-5 in maturity. Mat urity and pubescence color were recorded in 376 F3 progeny rows. The data d id not fit a single locus model or a two loci dominant epistasis model (12: 3:1). The E7 allele was partially, but not completely, dominant over the e7 allele. Therefore, a new locus E7 is proposed. Using the F3 segregation da ta, linkage between T and E1 was estimated to be 1.3 +/-0.6 centimorgan (cM ). Linkage between E1 and E7 was estimated to be 6.2 cM and linkage between E7 and T was estimated to be 3.9 cM. E7 is a new flowering, maturity, and photoperiod sensitivity locus tightly linked to both E1 and T. E7E7 results in later flowering and maturity, and sensitivity to long photoperiods prod uced by incandescent lamps when compared to e7e7.