Allelic variation of soybean flower color gene W4 encoding dihydroflavonol 4-reductase 2

Abstract

BackgroundFlower color of soybean is primarily controlled by six genes, viz., W1, W2, W3, W4, Wm and Wp. This study was conducted to investigate the genetic and chemical basis of newly-identified flower color variants including two soybean mutant lines, 222-A-3 (near white flower) and E30-D-1 (light purple flower), a near-isogenic line (Clark-w4), flower color variants (T321 and T369) descended from the w4-mutable line and kw4 (near white flower, Glycine soja).ResultsComplementation tests revealed that the flower color of 222-A-3 and kw4 was controlled by the recessive allele (w4) of the W4 locus encoding dihydroflavonol 4-reductase 2 (DFR2). In 222-A-3, a single base was deleted in the first exon resulting in a truncated polypeptide consisting of 24 amino acids. In Clark-w4, base substitution of the first nucleotide of the fourth intron abolished the 5′ splice site, resulting in the retention of the intron. The DFR2 gene of kw4 was not expressed. The above results suggest that complete loss-of-function of DFR2 gene leads to near white flowers. Light purple flower of E30-D-1 was controlled by a new allele at the W4 locus, w4-lp. The gene symbol was approved by the Soybean Genetics Committee. In E30-D-1, a single-base substitution changed an amino acid at position 39 from arginine to histidine. Pale flowers of T369 had higher expression levels of the DFR2 gene. These flower petals contained unique dihydroflavonols that have not yet been reported to occur in soybean and G. soja.ConclusionsComplete loss-of-function of DFR2 gene leads to near white flowers. A new allele of the W4 locus, w4-lp regulates light purple flowers. Single amino acid substitution was associated with light purple flowers. Flower petals of T369 had higher levels of DFR2 gene expression and contained unique dihydroflavonols that are absent in soybean and G. soja. Thus, mutants of the DFR2 gene have unique flavonoid compositions and display a wide variety of flower color patterns in soybean, from near white, light purple, dilute purple to pale.

Dihydroflavonol 4-reductase activity is associated with the intensity of flower colors in delphinium

“…Recent reports in anthurium and soybean have confirmed the strong correlation between color intensity and anthocyanin accumulation (Gopaulchan et al 2014;Yan et al 2014). To determine whether this effect also occurred in delphinium, we measured the amounts of anthocyanin in the sepals of the six varieties.…”

Molecular Genetic Analysis of a Novel Recessive White Flower Gene in Wild Soybean

“…Yan et al (2014) reported a w4 mutant line and its w4 nucleotide sequence from a potential wild soybean. This is likely the first true finding of a recessive w4 allele from a wild soybean (G. soja).…”

“…However, only one synonymous SNP was identified in the exon region, indicating that the same amino acid sequence was encoded by DFR2 in both YWS415 and W4 soybean accessions in the absence of the transposon insertion (Xu et al, 2010;Yan et al, 2014;Sundaramoorthy et al, 2016). KY744345) of YWS415 covered the postulated full-length coding sequence of DFR2.…”

“…Linkage analysis of the markers was performed using CarthaGene version 1.2 (Schiex and Gaspin, 1997). Six fulllength nucleotide sequences of DFR2 (Xu et al, 2010;Yan et al, 2014;Sundaramoorthy et al, 2016) were downloaded for comparison with our two DFR2 sequences. Relationships among the DFR2 sequences were assessed using ClustalW and the neighbor-joining and bootstrap method implemented in MEGA6 (Tamura et al, 2013).…”

In silico Identification and Characterization of Conserved miRNAs and their Targets in Pigeon pea (Cajanus cajan L.) Expressed Sequence Tags

“…The miRNA cca-miR395a targets ATP sulfurylase that involves in sulfur assimilation and improves nutrient content of the plant, Dihydroflavonol-4-reductase enzyme that controls seed coat and flower colour in soybean (Herrmann et al, 2014;Yan et al, 2014). The miRNA cca-miR5219 suppresses the expression of 60S ribosomal protein L9 and peptidyl-prolyl cis-trans isomerase which help in translation elongation and protein peptidyl-prolyl isomerization respectively.…”