Coleus forskohlii: advancements and prospects of in vitro biotechnology

Coleus forskohlii syn. Plectranthus barbatus is a popular medicinal plant belonging to the family Lamiaceae and order Lamiales. The leaf and root extracts can be utilized for the treatment of various ailments like bronchitis, asthma, hay fever, angina and abdominal disorders. The major metabolite that is found exclusively in the cork cells of the root in C. forskohlii is forskolin, which is used commercially for the treatment of glaucoma, asthma and several heart ailments. The essential oil extracted from the tubers of the plant also exhibits anti-microbial properties. The present review recounts the existing reports on biotechnological approaches like direct, indirect organogenesis and somatic embryogenesis for mass propagation of plantlets; the amelioration of forskolin production through cell suspension and genetic transformation as well as slow growth storage for germplasm conservation. Additionally, the unexplored arenas and the prospective novel approaches are also addressed in this review that can be utilized in designing new experiments in near future on this plant.

A highly efficient organogenesis protocol based on zeatin riboside for in vitro regeneration of eggplant

BACKGROUND

Efficient organogenesis induction in eggplant (Solanum melongena L.) is required for multiple in vitro culture applications. In this work, we aimed at developing a universal protocol for efficient in vitro regeneration of eggplant mainly based on the use of zeatin riboside (ZR). We evaluated the effect of seven combinations of ZR with indoleacetic acid (IAA) for organogenic regeneration in five genetically diverse S. melongena and one S. insanum L. accessions using two photoperiod conditions. In addition, the effect of six different concentrations of indolebutyric acid (IBA) in order to promote rooting was assessed to facilitate subsequent acclimatization of plants. The ploidy level of regenerated plants was studied.

RESULTS

In a first experiment with accessions MEL1 and MEL3, significant (p < 0.05) differences were observed for the four factors evaluated for organogenesis from cotyledon, hypocotyl and leaf explants, with the best results obtained (9 and 11 shoots for MEL1 and MEL3, respectively) using cotyledon tissue, 16 h light / 8 h dark photoperiod conditions, and medium E6 (2 mg/L of ZR and 0 mg/L of IAA). The best combination of conditions was tested in the other four accessions and confirmed its high regeneration efficiency per explant when using both cotyledon and hypocotyl tissues. The best rooting media was R2 (1 mg/L IBA). The analysis of ploidy level revealed that between 25 and 50% of the regenerated plantlets were tetraploid.

CONCLUSIONS

An efficient protocol for organogenesis of both cultivated and wild accessions of eggplant, based on the use of ZR, is proposed. The universal protocol developed may be useful for fostering in vitro culture applications in eggplant requiring regeneration of plants and, in addition, allows developing tetraploid plants without the need of antimitotic chemicals.