Regulation mechanisms of flavonoids biosynthesis of Hancheng Dahongpao peels (Zanthoxylum bungeanum Maxim) at different development stages by integrated metabolomics and transcriptomics analysis.

BACKGROUND: Flavonoids have strong free radical scavenging and antioxidant capacity. The high abundance of flavonoids in Chinese prickly ash peels have many benefits to human health. In this study, 'Hancheng Dahongpao', a main cultivar, was taken as materials to investigate the flavonoids biosynthesis mechanism of Zanthoxylum bungeanum Maxim at three key development stages by integration of metabolomics and transcriptomics analysis. RESULTS: A total of 19 differentially accumulated metabolites were identified, the key flavonoids compounds were kaempferol, quercetin and their glycoside derivatives, and two major anthocyanins (peonidin O-hexoside and peonidin 3-O-glucoside). 5 gene networks/modules including 15 important candidate genes were identified, which was highly correlated with flavonoids. Among these genes, ZM-163828 and ZM-184209 were strongly correlated with kaempferol and quercetin, and ZM-125833 and ZM-97481 were controlled the anthocyanins biosynthesis. Moreover, it was shown that MYB-ZM1, MYB-ZM3, MYB-ZM5, MYB-ZM6 and MYB-ZM7 coordinately controlled flavonoids accumulation through regulating the structural genes. CONCLUSIONS: Generally, this study systematically revealed the flavonoids metabolic pathways and candidate genes involved in flavonoids biosynthesis and laid a foundation for the potential targets for the breeding of new valuable Chinese prickly ash cultivars.

Quality Evaluation of Wild Germplasm of Chinese Prickly Ash (Zanthoxylum bungeanum Maxim) from Qinling Mountains at Different Elevations Based on HPLC-Fingerprint.

Wild Chinese prickly ash resources provide a valuable genetic resource for Zanthoxylum bungeanum Maxim improvement and breeding. The Qinling Mountains was an abundant source for wild Chinese prickly ash. In this study, the phenolic and flavonoid compounds of wild germplasm resources from different altitudes and six cultivated varieties were analyzed by high performance liquid chromatography (HPLC). The chromatograms of them were essentially consistent, although their chemical composition contents were greatly different. The thirty samples were divided into three categories through the hierarchical clustering analysis. Catechin, hyperoside and quercitrin were considered to be key compounds for the quality evaluation, and by contrast, the wild samples with an altitude of 2300±50 m (Group IV) had the highest content of key compounds, and presented stronger antioxidant activity and antibacterial ability, indicating that these wild samples could be identified as the excellent breeding resources. This is the first time to evaluate the quality of wild Chinese prickly ash at different altitudes in Qinling Mountains. These excellent wild germplasm resources provided substantial potential accessions for use directly in Chinese prickly ash breeding programs.

Chemotaxonomic variation in volatile component contents and their correlation between climate factors in Chinese prickly ash peels (Zanthoxylum bungeanum Maxim.).

In this study, we analyzed the characteristics of volatile compounds of Chinese prickly ash peels with different climate conditions and their correlation. The data revealed that the contents of limonene and linalool in peels from southwest and northwest regions were higher, and the aroma was stronger, while the contents of ß-myrcene and (E)-ocimene in them from north, east and central China were higher, and the spicy flavor was heavier. Hierarchical cluster analysis demonstrated that the classification had geographical continuity. Through the correlation analysis and path analysis, it was found that the contents of volatile compounds were closely related to the climatic factors. The influence of wind speed and annual average temperature on volatile substances was greater than that of annual average precipitation and annual sunshine duration. This enriched the effect of climatic factors on the accumulation of volatile substances, and promoted the agriculture practices in area having similar climate conditions.

Transcriptome and metabolome analyses reveal the regulation of peel coloration in green, red Chinese prickly ash (Zanthoxylum L.).

Peel colour is an important external economic characteristic of Chinese prickly ash cultivars (Zanthoxylum bungeanum Maxim.). To gain insight into their coloration mechanisms, we performed an integrated analysis of green and red peels using combined metabolomic and transcriptomic analyses. Pelargonin-O-hexoside-O-rhamnoside-O-hexoside, pelargonidin 3,5-diglucoside, peonidin O-hexoside, cyanidin O-syringic acid and peonidin 3-O-glucoside were found to be the key anthocyanins. Transcriptome data indicated that the anthocyanidin synthase genes and UDP-glucose flavonoid 3-O-glucosytransferase genes were significantly increased to promote the redness of the peels. In addition, we discussed the role of R2R3-MYB transcription factors in coloration, of which the c80935 and c226097 genes may be the key regulatory factors for anthocyanin biosynthesis. Generally, this is the first study to identify and reveal the main anthocyanins in Chinese prickly ash peels during different developmental periods. The results of this research lay the foundation for understanding the regulation of coloration in Chinese prickly ash peels.