New Allelic Variant Discovered at Soybean Flower Color Locus W1 Encoding Flavonoid 3′5′‐hydroxylase

Abstract

A soybean line producing light purple flowers (E023‐H‐12) was developed from an ethyl methanesulfonate (EMS)‐treated population of cultivar Bay. The objective of this study was to investigate the genetic and molecular basis of flower color variation in E023‐H‐12. Genetic analysis suggested that the W1 gene encoding a flavonoid 3′5′‐hydroxylase (F3′5′H) controls light purple flower color. A single plant with purple flowers was generated in an F2 population derived from a cross between E023‐H‐12 and Clark‐w1 with white flowers, probably because of intragenic recombination of the F3′5′H gene. The allele for light purple flower was designated as w1‐lp2. The dominance relationships of the locus were W1 > w1‐lp2 > w1. Flower petals of E023‐H‐12 had similar expression levels of the F3′5′H gene but they had 42% less anthocyanins compared with Bay. The lower anthocyanin content may account for the light purple color of this mutant line. The nucleotide sequence of the F3′5′H gene of E023‐H‐12 had a single nucleotide polymorphism (SNP) resulting in alteration of an amino acid (H137L). A derived cleaved amplified polymorphic sequence (dCAPS) marker to discriminate the SNP co‐segregated with flower color. Thus, the amino acid substitution may be responsible for the lower anthocyanin content, and, consequently, light purple flower color.

Genetic and Chemical Analysis of Deep Purple Flower in Soybean

“…Mutants of the W4 (DFR2) gene have unique flavonoid compositions and display a wide variety of flower color patterns in soybean, from near white (w4), light purple (w4-lp), dilute purple (w4-dp), purple-near white variegation (w4-m) to pale (w4-p) (Palmer and Groose, 1993;Xu and Palmer, 2005;Xu et al, 2010;Yan et al, 2014). Mutants at the W1 (F3'5'H) locus produce flowers ranging from white (w1), light purple (w1-lp, w1-lp2) to variegated purple-white (w1-m) (Takahashi et al, 2010(Takahashi et al, , 2012Yan et al, 2016). Mutation of the W2 gene results in high vacuolar pH and bluer (purple-blue) flower petals (Takahashi et al, 2008(Takahashi et al, , 2011.…”