Characterization and quantitative trait locus mapping of late-flowering from a thai soybean cultivar introduced into a photoperiod-insensitive genetic background.

Reference Report for AP20210708.6

Title:	Characterization and quantitative trait locus mapping of late-flowering from a thai soybean cultivar introduced into a photoperiod-insensitive genetic background.
Authors:	Sun, F., Xu, M., Park, C., Dwiyanti, M. S., Nagano, A. J., Zhu, J., Watanabe, S., Kong, F., Liu, B., Yamada, T., Abe, J.
Source:	Sun et al. 2019 Plos ONE, 14(2): e0226116
Abstract:	The timing of both flowering and maturation determine crop adaptability and productivity. Soybean (Glycine max) is cultivated across a wide range of latitudes. The molecular-genetic mechanisms for flowering in soybean have been determined for photoperiodic responses to long days (LDs), but remain only partially determined for the delay of flowering under short-day conditions, an adaptive trait of cultivars grown in lower latitudes. Here, we characterized the late-flowering (LF) habit introduced from the Thai cultivar K3 into a photoperiod-insensitive genetic background under different photo-thermal conditions, and we analyzed the genetic basis using quantitative trait locus (QTL) mapping. The LF habit resulted from a basic difference in the floral induction activity and from the suppression of flowering, which was caused by red light-enriched LD lengths and higher temperatures, during whichFLOWERING LOCUS T(FT) orthologs,FT2aandFT5a, were strongly down-regulated. QTL mapping using gene-specific markers for flowering genesE2,FT2aandFT5aand 829 single nucleotide polymorphisms obtained from restriction-site associated DNA sequencing detected three QTLs controlling the LF habit. Of these, a QTL harboringFT2aexhibited large and stable effects under all the conditions tested. A resequencing analysis detected a nonsynonymous substitution in exon 4 ofFT2afrom K3, which converted the glycine conserved in FT-like proteins to the aspartic acid conserved in TERMINAL FLOWER 1-like proteins (floral repressors), suggesting a functional depression in the FT2a protein from K3. The effects of the remaining two QTLs, likely corresponding toE2andFT5a, were environment dependent. Thus, the LF habit from K3 may be caused by the functional depression of FT2a and the down-regulation of twoFTgenes by red light-enriched LD conditions and high temperatures.

Funded by the USDA-ARS. Developed by the USDA-ARS SoyBase and Legume Clade Database group at the Iowa State University, Ames, IA

U.S. Public Domain