The Soybean Stem Growth Habit Gene Dt1 Is an Ortholog of Arabidopsis TERMINAL FLOWER1      

Abstract

Classical genetic analysis has revealed that the determinate habit of soybean (Glycine max) is controlled by a recessive allele at the determinate stem (Dt1) locus. To dissect the molecular basis of the determinate habit, we isolated two orthologs of pea (Pisum sativum) TERMINAL FLOWER1a, GmTFL1a and GmTFL1b, from the soybean genome. Mapping analysis indicated that GmTFL1b is a candidate for Dt1. Despite their high amino acid identity, the two genes had different transcriptional profiles. GmTFL1b was expressed in the root and shoot apical meristems (SAMs), whereas GmTFL1a was mainly expressed in immature seed. The GmTFL1b transcript accumulated in the SAMs during early vegetative growth in both the determinate and indeterminate lines but thereafter was abruptly lost in the determinate line. Introduction of the genomic region of GmTFL1b from the indeterminate line complemented the stem growth habit in the determinate line: more nodes were produced, and flowering in the terminal raceme was delayed. The identity between Dt1 and GmTFL1b was also confirmed with a virus-induced gene silencing experiment. Taken together, our data suggest that Dt1 encodes the GmTFL1b protein and that the stem growth habit is determined by the variation of this gene. The dt1 allele may condition the determinate habit via the earlier loss in GmTFL1b expression concomitant with floral induction, although it functions normally under the noninductive phase of flowering. An association test of DNA polymorphisms with the stem growth habit among 16 cultivars suggested that a single amino acid substitution in exon 4 determines the fate of the SAM after floral induction.

Resequencing 302 wild and cultivated accessions identifies genes related to domestication and improvement in soybean

“…We identified some local differentiation signals that have not been detected previously in the screening of domestication and improvement selection, such as the E1 gene, which is responsible for the major flowering time (FT) QTL 29,30 . Typically, soybeans in northern regions have shorter maturity periods, whereas those in southern regions have longer maturity periods 31 .…”

Genetic Variation in Soybean at the Maturity Locus E4 Is Involved in Adaptation to Long Days at High Latitudes

“…The soybean TFL1 ortholog consists of two homoeologs, GmTFL1a and GmTFL1b, the latter of which is the determinate growth habit gene Dt1 [38,39]. The two homoeologs are expressed differently: GmTFL1b is expressed mainly in the vegetative SAM and the roots, whereas GmTFL1a is expressed mainly in the stem tip after flowering and in the immature cotyledons [39]. Arabidopsis TFL1 is highly expressed in the shoot apex and roots and weakly in the seeds and siliques (Arabidopsis eFP Browser [40,41]).…”

Application of somatic embryos to rapid and reliable analysis of soybean seed components by RNA interference-mediated gene silencing

“…Bean pod mottle virus-based vectors are an efficient and well-established tool for analysis of gene function in soybean, but such vectors were found not to induce gene silencing in seeds (Kachroo et al 2008;Zhang and Ghabrial 2006). In contrast, cucumber mosaic virus-and apple latent spherical virus-based vectors induced gene silencing in both the vegetative and reproductive stages in soybean and were shown to affect metabolite concentrations in soybean seeds (Liu et al 2010;Nagamatsu et al 2007;Yamagishi and Yoshikawa 2009). However, the efficacy of induced gene silencing and the extent of induced symptoms varied with the specific combinations of each of these three types of viral vector and soybean cultivars.…”