GEPHE SUMMARY Print
Gephebase Gene
Entry Status
Published
GepheID
GP00000946
Main curator
Martin
PHENOTYPIC CHANGE
Trait Category
Trait State in Taxon A
Glycine max - black hila
Trait State in Taxon B
Glycine max - brown hila
Ancestral State
Data not curated
Taxonomic Status
Taxon A
Latin Name
Common Name
soybean
Synonyms
soybean; soybeans; Glycine max (L.) Merr.; Glycine max; cv. Wye
Rank
species
Lineage
Show more ... angiospermae; eudicotyledons; Gunneridae; Pentapetalae; rosids; fabids; Fabales; Fabaceae; Papilionoideae; 50 kb inversion clade; NPAAA clade; indigoferoid/millettioid clade; Phaseoleae; Glycine; Soja
NCBI Taxonomy ID
is Taxon A an Infraspecies?
Yes
Taxon A Description
Glycine max - black hila
Taxon B
Latin Name
Common Name
soybean
Synonyms
soybean; soybeans; Glycine max (L.) Merr.; Glycine max; cv. Wye
Rank
species
Lineage
Show more ... angiospermae; eudicotyledons; Gunneridae; Pentapetalae; rosids; fabids; Fabales; Fabaceae; Papilionoideae; 50 kb inversion clade; NPAAA clade; indigoferoid/millettioid clade; Phaseoleae; Glycine; Soja
NCBI Taxonomy ID
is Taxon B an Infraspecies?
Yes
Taxon B Description
Glycine max - brown hila
GENOTYPIC CHANGE
UniProtKB
Glycine max
GenebankID or UniProtKB
Presumptive Null
Yes
Molecular Type
Aberration Type
SNP
SNP Coding Change
Nonsense
Molecular Details of the Mutation
C377- creating premature Stop
Experimental Evidence
Taxon A Taxon B Position
Codon - - -
Amino-acid - - -
Authors
Gillman JD; Tetlow A; Lee JD; Shannon JG; Bilyeu K
Abstract
Although modern soybean cultivars feature yellow seed coats, with the only color variation found at the hila, the ancestral condition is black seed coats. Both seed coat and hila coloration are due to the presence of phenylpropanoid pathway derivatives, principally anthocyanins. The genetics of soybean seed coat and hilum coloration were first investigated during the resurgence of genetics during the 1920s, following the rediscovery of Mendel's work. Despite the inclusion of this phenotypic marker into the extensive genetic maps developed for soybean over the last twenty years, the genetic basis behind the phenomenon of brown seed coats (the R locus) has remained undetermined until now.

In order to identify the gene responsible for the r gene effect (brown hilum or seed coat color), we utilized bulk segregant analysis and identified recombinant lines derived from a population segregating for two phenotypically distinct alleles of the R locus. Fine mapping was accelerated through use of a novel, bioinformatically determined set of Simple Sequence Repeat (SSR) markers which allowed us to delimit the genomic region containing the r gene to less than 200 kbp, despite the use of a mapping population of only 100 F6 lines. Candidate gene analysis identified a loss of function mutation affecting a seed coat-specific expressed R2R3 MYB transcription factor gene (Glyma09g36990) as a strong candidate for the brown hilum phenotype. We observed a near perfect correlation between the mRNA expression levels of the functional R gene candidate and an UDP-glucose:flavonoid 3-O-glucosyltransferase (UF3GT) gene, which is responsible for the final step in anthocyanin biosynthesis. In contrast, when a null allele of Glyma09g36990 is expressed no upregulation of the UF3GT gene was found.

We discovered an allelic series of four loss of function mutations affecting our R locus gene candidate. The presence of any one of these mutations was perfectly correlated with the brown seed coat/hilum phenotype in a broadly distributed survey of soybean cultivars, barring the presence of the epistatic dominant I allele or gray pubescence, both of which can mask the effect of the r allele, resulting in yellow or buff hila. These findings strongly suggest that loss of function for one particular seed coat-expressed R2R3 MYB gene is responsible for the brown seed coat/hilum phenotype in soybean.
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