Combined Metabolome and Transcriptome Analyses of Young, Mature, and Old Rhizome Tissues of Zingiber officinale Roscoe

Integrated non-targeted metabolomics and transcriptomics reveals the browning mechanism of scraped ginger (Zingiber officinale Rosc.)

Ginger (Zingiber officinale Rosc.) possesses a rich nutritional profile, making it a valuable ingredient for a wide range of culinary applications. After removing its outer skin, ginger can be effectively utilized in the production of pickles and other processed food products. However, following scraping, ginger undergoes a series of physiological and biochemical changes during storage, which can impact its subsequent development and utilization in food. Thus, the current study aimed to investigate the browning mechanism of scraped ginger using non-targeted metabolomics and transcriptomics. The findings revealed 149 shared differential metabolites and 639 shared differential genes among freshly scraped ginger, ginger browned for 5 days, and ginger browned for 15 days. These metabolites and genes are primarily enriched in stilbenes, diarylheptane, and gingerol biosynthesis, phenylpropanoid biosynthesis, and tyrosine metabolism. Through the combined regulation of these pathways, the levels of phenolic components (such as chlorogenic acid and ferulic acid) and the ginger indicator component (6-gingerol) decreased, whereas promoting an increase in the content of coniferaldehyde and curcumin. Additionally, the activities of polyphenol oxidase (PPO) and peroxidase (POD) were significantly increased (p-adjust <0.05). This study hypothesized that chlorogenic and ferulic acid undergo polymerization under the catalysis of PPO and POD, thereby exacerbating the lignification of scraped ginger. These findings offer a theoretical foundation for understanding the browning mechanism of ginger after scraping. PRACTICAL APPLICATION: Ginger's quality and nutrition can change when its skin is removed. This happens due to physical and biochemical reactions during scraping. The browning that occurs affects both the taste and health benefits of ginger, we can better understand how to prevent browning and maintain ginger's quality. This research sheds light on improving ginger processing techniques for better products.

Metabolomics of natural samples: A tutorial review on the latest technologies

Metabolomics is the study of metabolites present in a living system. It is a rapidly growing field aimed at discovering novel compounds, studying biological processes, diagnosing diseases, and ensuring the quality of food products. Recently, the analysis of natural samples has become important to explore novel bioactive compounds and to study how environment and genetics affect living systems. Various metabolomics techniques, databases, and data analysis tools are available for natural sample metabolomics. However, choosing the right method can be a daunting exercise because natural samples are heterogeneous and require untargeted approaches. This tutorial review aims to compile the latest technologies to guide an early-career scientist on natural sample metabolomics. First, different extraction methods and their pros and cons are reviewed. Second, currently available metabolomics databases and data analysis tools are summarized. Next, recent research on metabolomics of milk, honey, and microbial samples is reviewed. Finally, after reviewing the latest trends in technologies, a checklist is presented to guide an early-career researcher on how to design a metabolomics project. In conclusion, this review is a comprehensive resource for a researcher planning to conduct their first metabolomics analysis. It is also useful for experienced researchers to update themselves on the latest trends in metabolomics.

Dynamic transcriptome profiling provides insights into rhizome enlargement in ginger (Zingiber officinale Rosc.)

The rhizome is an economically important part of ginger (Zingiber officinale Rosc.). However, the mechanism of ginger rhizome enlargement remains unclear. In this study, we performed an integrated analysis of the hormone content and transcriptome of ginger at three rhizome enlargement stages: initial enlargement (S1), middle enlargement (S2), and peak enlargement (S3). With rhizome enlargement, the levels of the hormones zeatin (ZT), gibberellic acid (GA), indole acetic acid (IAA), and jasmonic acid (JA) were significantly increased, and this increase was positively correlated with rhizome diameter. Transcriptomic analysis identified a large number of differentially expressed genes (DEGs); the number of DEGs were 2,206 in the transition from S1 to S2, and 1,151 in the transition from S2 to S3. The expression of several genes related to hormone biosynthesis and signalling and cell division or expansion, and transcription factors was significantly altered, which suggests that these genes play essential roles in rhizome enlargement. The results of correlation analysis suggested that the process of ginger rhizome enlargement may be primarily related to the regulation of endogenous cytokinin, GA3, auxin, and JA biosynthesis pathways and signal transduction; GRAS, HB, MYB, MYB122, bZIP60, ARF1, ARF2, E2FB1, and E2FB2, which may regulate the expression of rhizome formation-related genes; and CYC2, CDKB1, CDKB2, EXPA1, and XTH7, which may mediate cell division and expansion. These results provide gene resources and information that will be useful for the molecular breeding in ginger.