Natural variation and geographical distribution of seed carotenoids and chlorophylls in 1167 Chinese soybean accessions

Understanding the composition and contents of carotenoids in various soybean seed accessions is valuable for its nutrition assessment. This study investigated the variability in concentrations of carotenoids and chlorophylls and unveil their associations with other nutritional quality traits of genetically diverse Chinese soybean accessions comprised cultivars and landraces. Genotype, planting year, accession type, seed cotyledon color, and ecoregion of origin significantly influenced accumulation of carotenoids and chlorophylls. The mean total carotenoid content found in the range of 8.15-14.72 µg g-1 across the ecoregions. Landraces contained 1.2-fold higher content of total carotenoid in comparison with that of cultivars. Soybeans with green cotyledon contained higher content of carotenoids and chlorophylls than those with yellow cotyledon. Remarkably, lutein was the most abundant carotenoid in all the germplasms, ranging from 1.35-37.44 µg g-1. Carotenoid and chlorophylls showed significant correlations with other quality traits, helping to set breeding strategies for enhancing soybean carotenoids without affecting other components. Collectively, our results demonstrate that carotenoids are adequately accumulated in soybean seeds, which however strongly influenced by genetic factors, accession type, germplasm origin, and we identified novel germplasms with the highest total carotenoid content across the ecoregions of China that could serve and utilize as genetic materials for soybean carotenoid breeding programs and thereby raw materials for food sectors, pharmaceuticals, and cosmetic industries.