Shoot organogenesis and somatic embryogenesis in Rehmannia glutinosa Libosch. - An important medicinal plant

Rehmannia glutinosa Libosch. is an important medicinal plant, listed as one of the 50 fundamental herbs used in Chinese medicine. In this study, callus mediated shoot organogenesis and somatic embryogenesis from leaf and petiole explants have been investigated. For shoot regeneration, Murashige and Skoog (MS) medium supplemented with different concentration of 6-benzyladenine (BA) such as 0, 1.0, 2.0, 3.0, 4.0, or 5.0 mg•L-1 along with 0.5 or 1.0 mg•L-1 indole-3-acetic acid (IAA) has been studied. For somatic embryogenesis, explants were cultured on MS medium containing 0, 1.0, or 2.0 mg•L-1 of 2, 4-dichlorophenoxyacetic acid (2, 4-D) in combination with 0 or 1.0 mg•L-1 of BA and/or gibberellic acid (GA3). The highest number of shoots (4.4±0.30) per explants was observed on leaf explants cultured in 3.0 mg•L-1 BA with 0.5 mg•L-1 IAA medium. On the other hand, the petiole explant cultured on 2.0 mg•L-1 2, 4-D medium induced the maximum (76.4%) embryogenic callus and 3.6±0.30 somatic embryos per explant. The conversion of plantlets from embryogenic callus was succeeded in half-MS medium supplemented with the 1.0 mg•L-1 BA and 1.0 mg•L-1 GA3. Plant growth regulators (PGRs) free-MS medium was used for in vitro rooting. Approximately 90% of plants were successfully survived in the greenhouse. Thus, we concluded from our results that leaf might be the best explant for shoot induction and multiplication whereas petiole can be the effective explant for somatic embryogenesis. Therefore, the developed protocol from our studies can be utilized for the large scale clonal propagation, germplasm conservation, and genetic manipulation of R. glutinosa.