In Vitro Microrhizome Production, Genetic Homogeneity Assessment, and Field Performance Evaluation in Ginger

In vitro-induced microrhizomes are promising for producing disease-free planting materials in ginger (Zingiber officinale Rosc.), spice and medicinal crops threatened by several soil-borne diseases. The study examined microrhizome induction, genetic homogeneity, and field performance in ginger. The condition combination of 3.0 mg·L-1 6-benzylaminopurine (BAP), 100 g·L–1 sucrose, and a 12-h photoperiod (the optimal conditions) produced the largest number of microrhizomes among all treatments but resulted in a lower average fresh weight during the 60-day culture period. Larger microrhizomes exhibited greater tolerance to water loss and a higher percentage of sprouting. Therefore, additional efforts were made to increase the size of the microrhizomes. Under the optimal conditions, the fresh weight increased significantly to 280.3 mg and 403.4 mg after 30 days of additional culture and in vitro culture of small-sized microrhizomes, respectively. Flow cytometry analysis and SSR characterization confirmed the genetic homogeneity of the regenerated plants with microrhizomes (MR) and those obtained by directly sowing sprouted microrhizomes into the substrate without acclimatization (FMR). At harvest, the MR had the most robust growth, a significantly higher fresh rhizome weight (206.1 g per plant) than the FMR (121.8 g per plant) and conventional tissue-cultured plants (TC), and similar rhizome finger size (11.5 g and 10.2 cm2) to the FMR. These findings suggest that both the MR and the FMR have advantages over the TC in producing seedling rhizomes of ginger in the first growing season. The established approach may be useful for large-scale production of disease-free ginger rhizomes.