Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/21/2002
Publication Date: 6/17/2003
Citation: TASMA, I.M., SHOEMAKER, R.C. MAPPING FLOWERING TIME GENE HOMOLOGS IN SOYBEAN AND THEIR ASSOCIATION WITH MATURITY (E) LOCI. CROP SCIENCE. 2003. v. 43. p. 319-328. Interpretive Summary: When and how a crop plant flowers, produces seed, and matures is very important to agriculture. Day length is an important trigger controlling these characters. Some soybeans respond to day length and some do not. Because soybean is a major agronomic seed crop it would be beneficial to understand the mechanisms that control flowering and maturity. Using computer databases, the authors identified 18 genes that affect flowering, recognition of day length, and maturity in other plants. They then mapped 10 of the genes onto the soybean genetic road map to see if their location corresponded to regions thought to be control flowering and maturity. They tested the genes using specially constructed soybean lines to see if any of the genes were associated with any of 7 known maturity genes. One gene, FCA, from Arabidopsis, corresponded to soybean maturity gene E3. This information is important to geneticists and physiologists because it begins sto dissect a very important biochemical process in soybean that impacts th geographic range in which we can grow soybean.
Technical Abstract: Time of flowering is a quantitatively inherited character important for developing soybean cultivars with a wider area of adaptation. The first objective of this study was to genetically map genes known to be involved in photoperiod recognition and time of flowering. The second objective was to correlate mapped genes with maturity (E) loci by means of near isogenic lines (NILs). Two recombinant inbred (RI) lines and an F2 population were used in the mapping study. One RI population, IX132, was developed by crossing PI317.336 and 'Corsoy'; the second, IX136, by crossing PI317.334B and 'Corsoy'. Both P.I.s have been reported to be photoperiod-insensitive. 'Corsoy' is photoperiod-sensitive. The F2 population was developed from an interspecific cross between G. max (breeding line A81-356022) and G. soja (PI 468.916). Eighteen soybean cDNA clones with high similarities to 18 previously cloned flowering time genes were used as probes. Ten of the 18 cDNA clones were mapped. The cDNAs were mapped onto linkage groups (LGs) A2 (CRY2), B1 and H (COL1), A1 and B2 (PHYA), C1 (DET1 and LD), D2 (AP2), E and K (PHYB), F (COL2), L (FCA), and Q (CCA1). None of the cDNAs were directly associated with previously mapped QTL for flowering time. However, analyses using contrasting NILs showed that FCA is a strong gene candidate for maturity locus E3. Analysis of NILs also suggest that PHYB may be associated with maturity locus E1.