Transcriptional Regulation of Key Biosynthetic and Regulatory Genes Governs Gingerol Variation in Zingiber officinale Genotypes
P. M. Munashi
Department of Molecular Biology and Biotechnology, Kerala Agricultural University Vellanikkara, Thrissur, India.
A. G. Kiran *
Department of Molecular Biology and Biotechnology, Kerala Agricultural University Vellanikkara, Thrissur, India.
Deepu Mathew
Department of Molecular Biology and Biotechnology, Kerala Agricultural University Vellanikkara, Thrissur, India.
R. Preetha
Department of Molecular Biology and Biotechnology, Kerala Agricultural University Vellanikkara, Thrissur, India.
K. P. Sayuj
Department of Biotechnology, Cochin University of Science and Technology, Kochi, Ernakulam, India.
*Author to whom correspondence should be addressed.
Abstract
Background: Ginger (Zingiber officinale) is a medicinally important spice rich in bioactive compounds, particularly 6-gingerol, which contributes to its characteristic pungency. These compounds exhibit diverse pharmacological activities, including anticancer, antibacterial, cardiovascular, and neuroprotective effects.
Aim: The present study aimed to identify key genes in the gingerol biosynthetic pathway that contribute to differential gingerol accumulation among selected ginger (Zingiber officinale Roscoe) cultivars.
Study Design: A comparative gene expression analysis was conducted using contrasting ginger cultivars with varying gingerol contents.
Place and Duration of Study: The study was conducted in the laboratory of the Centre for Plant Biotechnology and Molecular Biology from 2023 to 2026.
Methodology: Two ginger cultivars, Athira and Rio-de-Janeiro, exhibiting significant variation in gingerol content (0.780 mg g⁻¹ DW and 0.531 mg g⁻¹ DW, respectively), were selected based on high-performance liquid chromatography (HPLC) analysis. The expression levels of key biosynthetic genes, including phenylalanine ammonia-lyase (PAL), shikimate hydroxycinnamoyl transferase 1 (HCT1), and curcumin synthase (CURS), together with those of regulatory genes such as octopine synthase binding factor 4 (OBF4) and GATA-binding transcription factor 2 (GATA2), were analysed using reverse transcription quantitative PCR (RT-qPCR).
Results: All genes studied showed significantly higher expression in Athira than in Rio-de-Janeiro, with fold increases ranging from 1.2 to 2.8. Among these genes, CURS exhibited the greatest upregulation, suggesting a key role in gingerol biosynthesis. Elevated PAL expression suggested increased precursor availability through the phenylpropanoid pathway, whereas the moderate upregulation of OBF4 and GATA2 indicated their involvement in transcriptional regulation.
Conclusion: The study indicates that enhanced expression of both biosynthetic and regulatory genes is associated with greater gingerol accumulation in ginger cultivars. The observed association between gene expression and gingerol accumulation suggests that these genes could serve as candidate molecular markers for identifying high-gingerol genotypes, be used in in vitro elicitation studies, and represent potential targets for future metabolic engineering.
Keywords: Ginger, Gingerol, CURS, PAL, HCT1, OBF4, GATA2, HPLC