Photo-dependent somatic embryogenesis from non-embryogenic calli and its polyphenolics content in high-valued medicinal plant of Ajuga bracteosa

Abstract

Ajuga bracteosa (A. bracteosa) is one of the critically endangered and high-valued medicinal plants worldwide. Light is one of the major factor or stimulus involved in the morphogenic responses and bioactive compounds production in various medicinal plants. In this study, unique properties of colored lights have been observed on induction of somatic embryos from non-embryonic calli cultures of A. bracteosa. The maximum callogenic response (92.32%) from leaf explants was observed on Murashige and Skoog (MS) medium augmented with benzyl adenine (BA; 2.0 l−1) and 2, 4-Dichlorophenoxy acetic acid (2.4-D; 1.0 mg l−1). Calli cultures with same hormonal concentrations were placed under different spectral lights for somatic embryogenesis and photochemical variations. Red lights were found effective for maximum somatic embryos induction (92.75%) with optimum biomass accumulation (152.64 g l−1) on day 40. Similarly, among all the spectral lights, red light exhibited the highest DPPH-radical scavenging activity (DRSA; 92.86%). In contrast, blue lights induced maximum biosynthesis of chemically important total phenolics content and total flavonoids content (TPC; 0.264 and TFC; 0.06 mg/g-DW), respectively. Furthermore, blue, green and red lights also enhanced phenolics and production, polyphenolics content and total polyphenolics production in somatic embryos. It is concluded that exposure of calli cultures to colored lights provides an effective and promising in vitro technique for conservation of endangered A. bracteosa species and enhancement of its bioactive compounds. Steps should be taken to adopt these strategies/ techniques at a larger scale in order to yield maximum benefits from this highly valued medicinal plant species.