In vitro regeneration of the medicinal plant Cassia absus L.

Abstract

SummaryCassia absus L. is a medicinal plant with commercial value. In order to establish a protocol for its regeneration from nodal explants, C. absus was proliferated in vitro using 1.0_ Murashige and Skoog (MS) medium containing 3% (w/v) sucrose, 0.8% (w/v) agar, 0.05% (w/v) charcoal, and different concentrations of 6-benzylaminopurine (BAP), kinetin, zeatin, or isopentenyl adenine (2iP) under controlled temperature, humidity, and light conditions. Shoot induction was achieved at various rates on all media tested. MS medium containing 0.5 mg l-1 BAP gave the optimum results for shoot initiation and proliferation, with an average shoot length of 12.4 mm and an average of 2.7 leaves per shoot.The effect of 0.5 mg l-1 BAP combined with 0.1 mg l-1 gibberellic acid (GA3) was also tested under the same conditions to improve growth and increase shoot length. Shoots induced on this medium were significantly longer (13.4 mm) with more leaves (3.3 per shoot) than on 1.0_ MS medium containing 0.5 mg l-1 BAP alone. Explants with developed micro-shoots were transferred to 1.0_ MS multiplication medium supplemented with 0.1 mg l-1 GA3 plus different concentrations and combinations of BAP and an auxin [1-naphthaleneacetic acid (NAA) or indole 3-butyric acid (IBA)] for shoot multiplication and elongation. The maximum average of shoot length (35.0 mm) and the highest shoot elongation rate (SER = 2.4 mm shoot-1 week-1) were recorded on 1.0_ MS medium containing 0.5 mg l-1 BAP, 0.1 mg l-1 NAA, and 0.1 mg l-1 GA3. The elongated micro-shoots were excised and transferred onto to 1.0_ or 0.5_ MS medium supplemented with different concentrations of IBA or NAA for root induction. Shoots grown on 0.5_ MS medium with 2 mg l-1 IBA gave the maximum rooting percentage (93.8%) compared to those on 1.0_ MS medium (25%). A protocol for direct shoot induction has been established, however further research must be undertaken to increase the rate of shoot multiplication to produce viable plants.