In vitro propagation of medicinal and aromatic plants: the case of selected Greek species with conservation priority

Worldwide, many medicinal and aromatic plants (MAPs) are still collected from the wild and only a small fraction of them are exclusively sourced from cultivation. This practice when performed non-sustainably threatens species and populations. Micropropagation of MAPs is a powerful tool to conserve rare, threatened, and valuable MAPs, and to massively produce high-value plant material for cultivation without seasonal constraints. In this study, the in vitro propagation protocols of 22 Greek native MAPs assigned with conservation priority were assessed (herbaceous perennials, bulbous, subshrubs, and trees), including 17 range-restricted plants and 5 taxa of Orchidaceae. For the latter, current micropropagation efforts include seed germination, callus induction, and protocorm formation for successful plantlet development; however, these propagation protocols are still fragmentary. For the rest (n = 17), a five-stage detailed procedure is outlined (plant material, establishment, proliferation, rooting, and acclimatization), while materials, treatments, and data per stage are shown comparatively and discussed. Emphasis is given on the selection and preparation of plant material obtained from nature for research, sustainable use, and ex situ conservation actions, and on their effectiveness for conservation purposes or mass production needs. The protocol effectiveness was calculated using a specific equation to estimate the potential number of acclimatized plants raised from a single explant within a year. All protocols can facilitate conservation, and almost half of them could be used for commercialization with high cost (five cases), intermediate cost (eight), or low cost (four), which enables their possible sustainable use.