QTL mapping for photoperiod insensitivity of a Japanese soybean landrace Sakamotowase.

The insensitivity of flowering to long daylength is an important characteristic which soybeans have used to adapt to environments at higher latitude. The objective of this study was to map the novel gene(s) for photoperiod insensitivity in the Japanese soybean landrace Sakamotowase. A previous study suggested that Sakamotowase possessed the genotype e1e1e3e3E4E4. The progeny of testcrosses with the Harosoy isoline for e3 (L62-667) produced the roughly expected segregation pattern for the monogenic inheritance, suggesting the major involvement of a single gene in photoperiod insensitivity of Sakamotowase. By mapping analysis for 6 linkage groups (LGs) harboring the known major genes and quantitative trait loci (QTLs) for flowering, we detected a major QTL for the insensitivity near an simple sequence repeat marker (Satt577) in LG C2 and a minor QTL in LG L. Our results therefore suggest that a novel gene for photoperiod insensitivity of Sakamotowase was located in LG C2. It was estimated from the position of the tagging marker that the novel gene may be an allele at the E1 or E7 loci or a novel gene tightly linked to the E1 locus.