Mapping of Quantitative Trait Loci Associated with Terminal Raceme Length in Soybean

Abstract

2461ReseaRch S oybean develops inflorescence meristems on each node, including the shoot apex. The flower clusters of the soybean raceme have a highly branched inflorescence structure, and their racemes are classified as terminal, primary, secondary, tertiary, and so on (Torigoe et al., 1982). Previous studies have reported a relationship between pod setting and raceme order. The increased yield of soybean at higher densities is associated with an increased share of pods of lower-order racemes (Kuroda et al., 1992). Pod setting and seed growth of the lower-order racemes is more important than higher-order racemes in determining soybean yield because seeds derived from lower-order racemes account for the majority of the yield (Isobe et al., 1995).Some studies have focused on the terminal raceme, the lowestorder raceme, or its length. It was found that TRL measurements could possibly be used to predict yield in the semideterminate aBSTRaCT Soybean [Glycine max (L.) Merr.] develops inflorescence meristems on each node, including the shoot apex. The flower clusters of the soybean raceme have a highly branched inflorescence structure, and their racemes are classified as terminal, primary, secondary, and so on. raceme phenotype is an important trait associated with the number of floral buds and pods, and is dependent on the genotype. The breeding line 1532-1 was characterized by remarkably long racemes at the shoot apex of the main stem. To identify quantitative trait loci (QTLs) conditioning the terminal raceme length (TrL), a recombinant inbred line (rIL) population was developed from a cross between 1532-1 and an ordinary cultivar, Toyoharuka. The rILs were divided into two groups according to their alleles for a maturity locus, E1. The early-maturing rIL group with the e1 genotype was used for QTL analysis of TrL, while the late-maturing rIL group with the E1 genotype could not mature normally and lodged severely. Analysis of the early-maturing group resulted in the identification of a stable QTL, qTRL18-1, where the 1532-1 allele had a positive effect on TrL. Another QTL, qTRL11-1, was detected only in the rILs with the 1532-1 alleles at the qTRL18-1 locus, indicating an interaction between qTRL18-1 and qTRL11-1. The qTRL18-1 locus was located in the proximal region of the Dt2 locus. No stable QTLs for flowering time or maturing time were detected in the proximal region of qTRL18-1 or qTRL11-1. our results provide a new strategy to increase pod number on the main stem by marker-assisted selection (MAS) for qTRL18-1 and qTRL11-1.

Positional Cloning of the Flowering Time QTL qFT12-1 Reveals the Link Between the Clock Related PRR Homolog With Photoperiodic Response in Soybeans

“…Flowering time and maturity regulated by photoperiod sensitivity genes or loci (Garner and Allard, 1927; Cober et al, 2014) have been reported for soybeans, E1 , E2 (Bernard, 1971), E3 (Buzzell, 1971), E4 (Buzzell and Voldeng, 1980), E5 (McBlain and Bernard, 1987), E6 (Bonato and Vello, 1999), E7 (Cober and Voldeng, 2001), E8 (Cober et al, 2010), E9 (Kong et al, 2014), E10 (Samanfar et al, 2017), and J (Ray et al, 1995). Moreover, many other quantitative trait loci (QTLs) have been mapped for flowering time and maturity using different populations (Tasma et al, 2001; Chapman et al, 2003; Watanabe et al, 2004; Funatsuki et al, 2005; Pooprompan et al, 2006; Komatsu et al, 2007; Khan et al, 2008; Liu and Abe, 2009; Cheng et al, 2011; Yamaguchi et al, 2014). A total of 293 QTLs on flowering time and maturity, including 104 QTLs of first flower, 178 QTLs of pod maturity (R8), 5 QTLs for pod maturity beginning (R7), and 6 QTLs for pod beginning (R3), have been documented in the public repository, Soybase ().…”

Yield and related traits for a soybean breeding line ‘Tokei 1122’ with QTLs for long terminal racemes under high planting density conditions

“…Consequently, T22 produced more pods and a higher seed yield than TH at high planting densities. According to Yamaguchi et al (2014), the long-raceme cultivars produce more flowers on the terminal raceme during the flowering period and more total pods at maturity than the conventional low-branching cultivars. However, according to Saito et al (1998), the number of pods is influenced more by the number of flowers than the pod-setting rate.…”

“…'Tokei 1122ʹ was the result of a cross between TH and line 1532-1, which produces a long terminal raceme. Line 1532-1 was developed from a cross between 'Tokei 971ʹ and 'Tokei 793ʹ (Yamaguchi et al, 2014). All of these crosses were completed at the Tokachi Agricultural Experiment Station in Hokkaido, Japan.…”

“…All of these crosses were completed at the Tokachi Agricultural Experiment Station in Hokkaido, Japan. The qTRL18-1 and qTRL11-1 of T22 (Yamaguchi et al, 2014) were derived from line 1532-1 and are associated with the production of long terminal racemes. Both T22 and TH are low-branching and determinate cultivars (dt1).…”

“…Thus, generating new low-branching cultivars with long terminal racemes may lead to enhanced yield under dense planting conditions via the increased number of pods per node and the number of pods per plant. Yamaguchi et al (2014) previously mapped two TRLrelated quantitative trait loci (qTRL18-1 and qTRL11-1) and determined that the TRL is related to the number of main stem pods. We developed the long-raceme cultivar 'Tokei 1122ʹ (T22) with two TRL-related quantitative trait loci to improve yield by increasing the number of pods per node under dense planting conditions.…”