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

Soybean cyst nematode (SCN) is one of the most devastating pathogen for soybean. Therefore, identification of resistant germplasm resources and resistant genes is needed to improve SCN resistance for soybean. Soybean varieties Huipizhiheidou and Wuzhaiheidou were distributed in China and exhibited broad spectrums of resistance to various SCN races. In this study, these two resistant varieties, combined with standard susceptible varieties (Lee and Essex), were utilized to identify the differentially expressed transcripts after infection with SCN race 4 between resistant and susceptible reactions by using the Affymetrix Soybean Genome GeneChip. Comparative analyses indicated that 21 common genes changed significantly in the resistant group, of which 16 increased and 5 decreased. However, 12 common genes changed significantly in the susceptible group, of which 9 increased and 3 decreased. Additionally, 27 genes were found in common between resistant and susceptible reactions. The 21 significantly changed genes in resistant reaction were associated with disease and defense, cell structure, transcription, metabolism, and signal transduction. The fold induction of 4 from the 21 genes was confirmed by quantitative RT-PCR (qRTPCR) analysis. Moreover, the gene ontology (GO) enrichment analyses demonstrated the serine family amino acid metabolic process and arginine metabolic process may play important roles in SCN resistance. This study provided a new insight on the genetic basis of soybean resistance to SCN race 4, and the identified resistant or resistant-related genes are potentially useful for SCN-resistance breeding in soybean.