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

• Published in: PloS one Vol. 14; no. 12; p. e0226116
• Main Authors: Sun, Fei, Xu, Meilan, Park, Cheolwoo, Dwiyanti, Maria Stefanie, Nagano, Atsushi J, Zhu, Jianghui, Watanabe, Satoshi, Kong, Fanjiang, Liu, Baohui, Yamada, Tetsuya, Abe, Jun
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 05.12.2019; Public Library of Science (PLoS)
• Subjects: Adaptability; Aspartic acid; Biology and Life Sciences; Chromosome Mapping; Cultivars; Deoxyribonucleic acid; DNA; DNA sequencing; Earth Sciences; Flow mapping; Flowering; Flowers - growth & development; Gene expression; Gene mapping; Gene regulation; Gene sequencing; Genes; Genomes; Glycine max; Glycine max - genetics; Glycine max - growth & development; Glycine max - radiation effects; High temperature; Hot Temperature; Life sciences; Light; Linkage Disequilibrium; Nucleotides; Photoperiod; Plant Proteins - genetics; Polymorphism, Genetic; Proteins; Quantitative trait loci; Quantitative Trait Loci - genetics; Repressors; Research and Analysis Methods; Single-nucleotide polymorphism; Social Sciences; Soybeans; Transcription factors; China; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0226116

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 which FLOWERING LOCUS T (FT) orthologs, FT2a and FT5a, were strongly down-regulated. QTL mapping using gene-specific markers for flowering genes E2, FT2a and FT5a and 829 single nucleotide polymorphisms obtained from restriction-site associated DNA sequencing detected three QTLs controlling the LF habit. Of these, a QTL harboring FT2a exhibited large and stable effects under all the conditions tested. A resequencing analysis detected a nonsynonymous substitution in exon 4 of FT2a from 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 to E2 and FT5a, were environment dependent. Thus, the LF habit from K3 may be caused by the functional depression of FT2a and the down-regulation of two FT genes by red light-enriched LD conditions and high temperatures.