Noncorrelation between Growth and Zerumbone Production in Zingiber zerumbet Smith

Root cultures were established through adventitious roots obtained either from direct or indirect organogenesis. The frequency of root response, number of roots per explant, root length, and zerumbone production were influenced by the concentrations and the types of auxins, initial root inoculum and the strength of the basic Murashige and Skoog (MS) salt in the culture media. It was crucial to decide the type of root explant and optimum media that supported both growth and bioactive compound production in the root cultures. In our study, we found that there was a noncorrelation in the optimised media for growth and zerumbone production in the root cultures of medicinal ginger Zingiber zerumbet Smith. Full strength (MS) medium was the optimum media for specific growth rates whereas zerumbone accumulation was higher in half strength MS medium for adventitious roots from direct (AdRD) and indirect (AdRId) organogenesis. AdRD was chosen over AdRId although the specific growth rate achieved was higher in the latter (7.2 x 10-2µ) than the former (5.5 x 10-2µ) based on the zerumbone accumulation performance. Subsequently, these AdRD root cultures were elicitated with methyl jasmonate which showed ten-folds increase in zerumbone production than the controls. This study could provide a scalable protocol for the production of zerumbone from adventitious root culture in the future.