AUTHOR=Zhao Yanyan , Cartabia Annalisa , Garcés-Ruiz Mónica , Herent Marie-France , Quetin-Leclercq Joëlle , Ortiz Sergio , Declerck Stéphane , Lalaymia Ismahen 

TITLE=Arbuscular mycorrhizal fungi impact the production of alkannin/shikonin and their derivatives in Alkanna tinctoria Tausch. grown in semi-hydroponic and pot cultivation systems

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1216029

DOI=10.3389/fmicb.2023.1216029

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p><italic>Alkanna tinctoria</italic> Tausch. is a medicinal plant well-known to produce important therapeutic compounds, such as alkannin/shikonin and their derivatives (A/Sd). It associates with arbuscular mycorrhizal fungi (AMF), which are known, amongst others beneficial effects, to modulate the plant secondary metabolites (SMs) biosynthesis. However, to the best of our knowledge, no study on the effects of AMF strains on the growth and production of A/Sd in <italic>A. tinctoria</italic> has been reported in the literature.</p></sec><sec><title>Methods</title><p>Here, three experiments were conducted. In Experiment 1, plants were associated with the GINCO strain <italic>Rhizophagus irregularis</italic> MUCL 41833 and, in Experiment 2, with two strains of GINCO (<italic>R. irregularis</italic> MUCL 41833 and <italic>Rhizophagus aggregatus</italic> MUCL 49408) and two native strains isolated from wild growing <italic>A. tinctoria</italic> (<italic>R. irregularis</italic> and <italic>Septoglomus viscosum</italic>) and were grown in a semi-hydroponic (S-H) cultivation system. Plants were harvested after 9 and 37 days in Experiment 1 and 9 days in Experiment 2. In Experiment 3, plants were associated with the two native AMF strains and with <italic>R. irregularis</italic> MUCL 41833 and were grown for 85 days in pots under greenhouse conditions. Quantification and identification of A/Sd were performed by HPLC-PDA and by HPLC-HRMS/MS, respectively. <italic>LePGT1</italic>, <italic>LePGT2</italic>, and <italic>GHQH</italic> genes involved in the A/Sd biosynthesis were analyzed through RT-qPCR.</p></sec><sec><title>Results</title><p>In Experiment 1, no significant differences were noticed in the production of A/Sd. Conversely, in Experiments 2 and 3, plants associated with the native AMF <italic>R. irregularis</italic> had the highest content of total A/Sd expressed as shikonin equivalent. In Experiment 1, a significantly higher relative expression of both <italic>LePGT1</italic> and <italic>LePGT2</italic> was observed in plants inoculated with <italic>R. irregularis</italic> MUCL 41833 compared with control plants after 37 days in the S-H cultivation system. Similarly, a significantly higher relative expression of <italic>LePGT2</italic> in plants inoculated with <italic>R. irregularis</italic> MUCL 41833 was noticed after 9 versus 37 days in the S-H cultivation system. In Experiment 2, a significant lower relative expression of <italic>LePGT2</italic> was observed in native AMF <italic>R. irregularis</italic> inoculated plants compared to the control.</p></sec><sec><title>Discussion</title><p>Overall, our study showed that the native <italic>R. irregularis</italic> strain increased A/Sd production in <italic>A. tinctoria</italic> regardless of the growing system used, further suggesting that the inoculation of native/best performing AMF is a promising method to improve the production of important SMs.</p></sec>