A new study published in The Plant Journal explores how both genetics and environmental factors, particularly temperature, influence seed coat color patterns in common beans (Phaseolus vulgaris), a crop central to global diets and seed markets.
Researchers examined 36 domesticated accessions representing a wide range of commercial classes, including partly white seed coat varieties like UC Tiger’s Eye and Vermont Appaloosa. By using whole-genome sequencing, the team identified specific gene interactions—especially those involving the T gene and modifiers such as Bip, Z, and J—that regulate partial pigmentation across different seed surfaces.
The study also found that temperature significantly impacts expression. In growth chamber trials, a 4°C increase resulted in an average 21% rise in pigmented seed coat area, suggesting that pigmentation is not fixed but responsive to environmental changes. This thermally induced pigmentation was linked to flavonoid biosynthesis pathways, particularly MBW complexes involving MYB, bHLH, and WD40 transcription factors.
For breeders and researchers, these findings offer a clearer understanding of how pigmentation can shift with both genotype and climate—a critical insight for market-class consistency, visual traits, and breeding resilience under changing temperatures.
Source:
Parker, T., Bolt, T., Williams, T., et al. “Seed color patterns in domesticated common bean are regulated by MYB‐bHLH‐WD40 transcription factors and temperature.” The Plant Journal, Aug. 2024. https://www.sciencedirect.com/science/article/abs/pii/S0048969725011957