A New Approach to Optimizing Propagation and Study of Medicinal Plants In Vitro: Profiling of Endogenous Growth Regulators and Human Neurotransmitters by LC-MS

Micropropagation allows for propagation of thousands or even millions of true-to-type plants from a range of cell types and tissues. These plants are pathogen-free, and often more uniform than field grown relatives. Additionally, micropropagation technology may be optimized for the production of desirable medicinal compounds. Efficiency of micropropagation depends on a balance of plant growth regulators (PGRs) in the growth medium with auxins inducing root development and cytokinins stimulating shoot formation; unfortunately, not all plants and tissues abide by this keystone principle. Conventional methods to optimize protocols are often costly, time consuming, and involve application of diverse PGRs or inhibitors thereof. We have developed and validated a method for quantification of the main classes of PGRs including three cytokinins, auxin, gibberellic acid, abscisic acid, three jasmonates, and two salicylates via a simple and easily adopted liquid chromatography-mass spectrometry method. It is proposed that by pre-screening tissues it will be possible to better predict ideal starting conditions for establishment of tissue cultures suitable for micropropagation. Additionally, it is often desirable to select starting materials rich in bioactive compounds such as the indoleamines, melatonin and serotonin or other neuroactive compounds such as dopamine, or 5-hydroxytryptophan. Thus, this method has also been modified to allow for quantification of these compounds. We propose a new strategy for the development and implementation of micropropagation protocols using simple, easily modified analytical methods, which may be employed to screen for desirable medicinal plant germplasm and streamline the production of consistent, high quality natural health products.