Strategies for Enhanced Production of Commercially Important Secondary Metabolites from In Vitro Established Cultures of Linum usitatissinlum L.

Abstract

Linum usitatissimum is an important cultivated, commercial and medicinal plant in the family Linacaea. This plant is also known as flax and their seeds are famous for their nutritional, medicinal and industrial purposes. Exploitation of Linum usitatissimum is context dependent. Commercially, it is used for manufacturing oflinen fiber hence the name flaxseed is given to such a variety of Linum usitatissimum, on the other hand seeds of a variety used for many nutritional and industrial applications are called linseed. Linum usitatissimum is generally cultivated in areas having moderate to cold climate. The plant has a slender stem, lanceolate leaves and pale blue flowers with five petals. Canada, Russia, United States, China and India are among the top growers of Linum usitatissimum. Worldwide production of flax is 2.5-3 million tonnes per year. This plant is lich in pharmaceutical compounds along with some important nutraceuticals. Novel compounds found in flax are polyphenols, comprising of two major classes-lignans and neolignans. Lignans like secoisolariciresinol diglucoside (SDG) and lariciresinol diglucoside (LDG) are potential anticancer compounds whereas, neolignans such as dehydrodiconiferyl alcohol glucoside (DCG) and guaiacylglycerol-~-coniferyl alcohol ether glucoside (GGCG) are used in antimicrobial and anti-inflammatory drugs. However, the yield of these medicinal compounds in natural habitat is low and their extraction from wild is an expensive process. For this reason, researchers are busy devising cost effective, reproducible and practical strategies to enhance producton of lignans and neolignans in in vitro established infrastructure. In the first experiment, we established callus cultures of Linum usitatissimum following protocol of Anjum et al. (2016). These cultures were derived from stem explants obtained from in vitro seed derived aseptic plantlets. The objective of this study was to evaluate the effects of qualitative and quantitative differences in culture medium along with varying photoperiod treatments, on growth kinetics and secondary metabolites production in callus cultures of Linw1'l usitatissimum. To this end, ~ 1 g callus was inoculated on three different culture media, namely Murashige and Skoog, Gamborg B5 and Schenk and Hildebrandt, and each culture on specific growth medium was kept under the influence of different photoperiod treatments viz. 16/8 h light and dark, continuous light and continuous dark, respectively. We observed differential effects of nutrient and photoperiods variation on growth kinetics and secondary metabolites