Integrated metabolomics and transcriptomic analysis of the flavonoid regulatory networks in Sorghum bicolor seeds.

BACKGROUND: The objective of this study was to reveal the flavonoid biosynthesis pathway in white (Z6), red (Z27) and black (HC4) seeds of the sweet sorghum (Sorghum bicolor) using metabolomics and transcriptomics, to identify different flavonoid metabolites, and to analyze the differentially expressed genes involved in flavonoid biosynthesis. RESULTS: We analyzed the metabolomics and transcriptomics data of sweet sorghum seeds. Six hundred and fifty-one metabolites including 171 flavonoids were identified in three samples. Integrated analysis of transcriptomics and metabolomics showed that 8 chalcone synthase genes (gene19114, gene19115, gene19116, gene19117, gene19118, gene19120, gene19122 and gene19123) involved in flavonoid biosynthesis, were identified and play central role in change of color. Six flavanone including homoeriodictyol, naringin, prunin, naringenin, hesperetin and pinocembrin were main reason for the color difference. CONCLUSIONS: Our results provide valuable information on the flavonoid metabolites and the candidate genes involved in the flavonoid biosynthesis pathway in sweet sorghum seeds.

Reactive oxygen species, antioxidant enzyme activity, and gene expression patterns in a pair of nearly isogenic lines of nicosulfuron-exposed waxy maize (Zea mays L.).

Nicosulfuron is a post-emergence herbicide used for weed control in maize fields (Zea mays L.). Here, the pair of nearly isogenic inbred lines SN509-R (nicosulfuron resistant) and SN509-S (nicosulfuron sensitive) was used to study the effect of nicosulfuron on growth, oxidative stress, and the activity and gene expression of antioxidant enzymes in waxy maize seedlings. Nicosulfuron treatment was applied at the five-leaf stage and water treatment was used as control. After nicosulfuron treatment, the death of SN509-S might be associated with increased oxidative stress. Compared with SN509-R, higher O2·- and H2O2 accumulations were observed in SN509-S, which can severely damage lipids and proteins, thus reducing membrane stability. The effects were exacerbated with extended exposure time. Both O2·- and H2O2 detoxification is regulated by enzymes. After nicosulfuron treatment, superoxide dismutase (SOD), catalase, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), and glutathione-S-transferase (GST) of SN509-S were significantly lower than those of SN509-R. Compared to SN509-R, ascorbate content (AA), glutathione (GSH) content, GSH to glutathione disulfide ratios, and AA to dehydroascorbate ratios significantly declined with increasing exposure time in SN509-S. Compared to SN509-S, nicosulfuron treatment increased the transcript levels of most of the APX genes except for APX1, and in contrast to Gst1, upregulated the transcription of sod9, MDHAR, DHAR, and GR genes in SN509-R. These results suggest that on a transcription level and in accordance with their responses, detoxifying enzymes play a vital role in the O2·- and H2O2 detoxification of maize seedlings under nicosulfuron exposure.