Micropropagation of an endangered medicinal plant, ant-plant, Myrmecodia tuberosa Jack., for conservation in Thailand

Abstract

Tubers of Myrmecodia tuberosa Jack. have been used in Thai traditional herbal medicine. Myrmecodia tuberosa Jack. (Rubiaceae) is an endemic epiphytic species which was found only in the southern part of Thailand. This plant has a mutualism relationship with ants so it is commonly called ant-plant. Ant-plant was traditionally used by local people as a medicine for several diseases for a century. Ant-plant contains important compounds, such as glycosides, vitamins, minerals, flavonoids, tocopherols, polyphenols, and tannins, which has antioxidant and anti-cancer properties. However, Myrmecodia tuberosa Jack. in natural source have decreased due to deforestation and forest smuggling for use as ornamental plant. It is rare in Thailand; therefore, availability of raw material is limited and an effective method of producing in vitro-derived plants for pharmaceutical reasons would be desirable. The stem segments (1.0 cm) were excised from 45-day-old aseptical seedlings of Myrmecodia tuberosa Jack. and cultured on MS (Murashige and Skoog, 1962) medium augmented with 6-benzylaminopurine (BAP) at different concentrations (0.0, 1.0, 3.0, and 5.0 mg L-1) either singly or in combination with α-naphthalene acetic acid (NAA) (0.5 mg L-1) for 90 days. The results revealed that the stem segments which were cultured on MS medium supplemented with 3.0 mg L-1 BAP, in combination with 0.5 mg L-1 NAA gave the highest frequency (100%) of multiple shoot formation with maximum number of shoots (86.25 shoots explant-1), shoot length (8.50 mm), root induction efficiency (100%), number of roots (16.25 roots explant-1), and root length (21.54 mm). The regenerated complete plantlets of Myrmecodia tuberosa Jack. were also successfully acclimatized under greenhouse conditions at 95% survival and grew normally within 45 days.