Study of the growth, artemisinin production and leaf volatilome of some micropropagated Artemisia annua clones inoculated or not with beneficial soil microorganisms

Artemisia annua is a medicinal plant appreciated for the production of many volatile compounds and for the artemisinin, a molecule recommended by the World Health Organization for the malaria treatment. However, artemisinin in planta concentration is very low and one strategy to improve plant biomass and artemisinin production may be the use of beneficial soil microorganisms, such as Arbuscular Mycorrhizal Fungi (AMF) and Plant Growth-Promoting Bacteria (PGPB). The effectiveness of these microbes varies according to the genetic compatibility between plant and microorganisms. The aim of this study was to evaluate the effect of clonal variability and beneficial soil microorganisms on 5 different genotypes of A. annua plant, propagated in vitro through the micropropagation technique. The different clone plants were inoculated or not with several beneficial soil microorganisms, and cultivated in controlled conditions. In a first phase, different experiments were performed to test clone in vivo stability, and to evaluate the mycorrhizal colonization in the root and plant growth responses after 60 days of cultivation. Afterwards, in the last experiment, the two most stable clones were inoculated and two samplings at different times (30 and 60 days) were carried out, and artemisinin concentration was also evaluated, using a HPLC method. The mycorrhizal colonization values varied in all the clones, according to the different used AMF and PGPB. Furthermore, the use of different combinations of microorganisms led to positive or negative effects on plant growth, in the different clones, also after 30 days of cultivation. The artemisinin concentration did not vary in the presence of microorganisms, but it showed different values between the two considered clones. Finally, a characterization of leaf volatilome was performed through GC-MS analysis in one clone, and the leaf volatile profile varied according to the plant age and to the different combinations of microbes.