White Seed Color in Common Bean (Phaseolus vulgaris L.) Results from Convergent Evolution in the P (Pigment) Gene

TitleWhite Seed Color in Common Bean (Phaseolus vulgaris L.) Results from Convergent Evolution in the P (Pigment) Gene
TypeJournal Article
JournalNew Phytologist


The presence of seed color in common bean (Phaseolus vulgaris) requires the dominant‐acting P (pigment) gene, and white seed is a recessive phenotype in all domesticated races of the species. P was classically associated with seed size, thus describing it as the first genetic marker for a quantitative trait. The molecular structure of P was characterized to understand the selection of white seeds during bean diversification and the relationship of P to seed weight. P was identified by homology searches, a genome‐wide association study (GWAS) and gene remodeling, and confirmed by gene silencing. Allelic variation was assessed by a combination of resequencing and marker development, and the relationship between P and seed weight was assessed by a GWAS study. P is a member of clade B of subclass IIIf of plant basic helix–loop–helix (bHLH) proteins. Ten race‐specific P alleles conditioned the white seed phenotype, and each causative mutation affected at least one bHLH domain required for color expression. GWAS analysis confirmed the classic association of P with seed weight. In common bean, white seeds are the result of convergent evolution and, among plant species, orthologous convergence on a single transcription factor gene was observed.


McClean, PE., Bett, KE., Stonehouse, R., Lee, R., Pflieger, S., Moghaddam, SM., Geffroy, V., Miklas, P., Mamidi, S.. White Seed Color in Common Bean (Phaseolus vulgaris L.) Results from Convergent Evolution in the P (Pigment) Gene. New Phytologist. 2018.

Related Species
Related Species 

Dry Bean are high in starch, protein and dietary fiber, as well as being an excellent source of iron, potassium, selenium, molybdenum, thiamine, vitamin B6 and folate. Dry beans take longer to cook then most pulses, although cooking time can be shortened by soaking dried beans before cooking. Dry Bean is a highly variable species with growth habits ranging from bush varieties growing 20-60cm tall to vine varieties growing 2-3m long. While dry bean varieties range in growth habit all have characteristic green or purple alternate leaves and long pods containing 4-6 kidney-shaped seeds.

Research Area
Research Area 
Breeding & Genetics

Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. ... [more]