Tissue-specific and novel secondary metabolites identified by SPME/GC-MS in Artemisia annua calli cultured under different wavelength

The controlled environment in the in vitro conditions allow for a stable and high-quality production of metabolites. Also, the use of different tissues, under in vitro conditions, can produce a profile of secondary metabolites different from those produced under conventional systems. The present study aimed to develop a protocol for in vitro calli induction and proliferation of Artemisia annua, and to compare the secondary metabolite profile of in vitro calli, in vitro plantlets, and plants cultivated ex vitro. The effects of different light wavelengths on the production of secondary metabolites were also evaluated. The presence of phytoregulators 6Benzylaminopurine (BAP) and Naphthalene Acetic Acid (NAA) promoted the induction and proliferation of calli, with an increase in diameter and fresh weight of the calli. SPME/GC-MS analysis showed differences in the profile of secondary metabolites produced by different A. annua cultivation systems and light wavelengths. White light sources (cold fluorescent) and red light (LEDs) resulted in a greater diversity of metabolites produced by the calli. In total, 25 metabolites were detected exclusively in calli of A. annua, four of which are reported for the first time in the species: menthyl acetate, geranyl acetate, 4-methoxy benzaldehyde, and alpha-santalene. Of these, six metabolites were uniquely identified in calli cultured under red LED, demonstrating calli response specificity. The results demonstrate the potential of in vitro culture of A. annua calli in the production of metabolites different from those obtained in different tissues, such as in vitro plantlets and plants grown in greenhouse.