Current developments on taxonomy, agronomy, bioactivity and in vitro micropropagation of two Malaysian ginger varieties: Zingiber officinale Rosc cv. Bentong and Zingiber officinale Rosc cv. Rubrum

Zingiber officinale Rosc., or ginger, is a widely cultivated tropical herb species belonging to the family Zingiberaceae. Ginger is renowned for its medicinal and culinary uses. In Malaysia, two prominent ginger varieties, Z. officinale Rosc. cv. Bentong (Bentong ginger) and Z. officinale Rosc. cv. Rubrum (red ginger), are highly valued for their distinctive properties and significant economic importance. Bentong ginger, recognised by its geographical indication associated with the Bentong district of Pahang, is characterised by elongated leafy stems up to 90 cm in height arising from large, horn-shaped rhizomes with a strong aroma and high phenolic contents. Owing to its high medicinal value, it is predominantly regarded as a superior option for promoting health and preventing disease. Meanwhile, red ginger, distinguished by its reddish-purple rhizomes, is well-known for its high levels of vanilloids, phenolics and flavonoids, contributing to its remarkable pharmacological properties. Both varieties are propagated through conventional vegetative methods, with Bentong ginger flourishing in highland areas and red ginger thriving in well-drained sandy loam soils. Recently, the increasing consumer demand for Bentong ginger and red ginger rhizomes has prompted researchers to adopt biotechnological approaches in enhance their production. In vitro micropropagation is one of the biotechnological alternatives, offering intriguing options for large-scale, disease-free ginger rhizomes. In this review, we highlight current knowledge into Bentong and red ginger, focusing on their taxonomy, morphology, cultivation practices, nutritional value and bioactive compounds, along with the incorporation of tissue culture techniques for their large-scale propagation.