AUTHOR=Rostkowska Cristina , Mota Caroline M. , Oliveira Taísa C. , Santiago Fernanda M. , Oliveira Lilian A. , Korndörfer Gaspar H. , Lana Regina M. Q. , Rossi Monica L. , Nogueira Neusa L. , Simonnet Xavier , Mineo Tiago W. P. , Silva Deise A.O. , Mineo José R. 

TITLE=Si-Accumulation In Artemisia annua Glandular Trichomes Increases Artemisinin Concentration, but Does Not Interfere In the Impairment of Toxoplasma gondii Growth

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01430

DOI=10.3389/fpls.2016.01430

ISSN=1664-462X

ABSTRACT=<p><italic>Artemisia annua</italic> is used as a source of artemisinin, a potent therapeutic agent used for the treatment of infectious diseases, chiefly malaria. However, the low concentration (from 0.01 to 1.4% of dried leaf matter) of artemisinin in the plant obtained with the traditional cropping system makes it a relatively expensive drug, especially in developing countries. Considering that artemisinin and silicon (Si) are both stored in <italic>A. annua</italic> glandular trichomes, and that Si accumulation has never been investigated, this study aimed to look into Si effects on <italic>A. annua</italic> trichome artemisinin concentration, and whether leaf infusion from Si-treated <italic>A. annua</italic> plants is able to control <italic>Toxoplasma gondii</italic> growth. <italic>T. gondii</italic> is the etiologic agent of toxoplasmosis, a zoonotic parasitic disease whose traditional treatment shows significant side effects. The experimental design consisted of <italic>A. annua</italic> seedlings randomly planted in soil treated with different doses of calcium/magnesium silicate (0, 200, 400, 800, and 1600 kg ha<sup>-1</sup>). Analysis of foliar macronutrients showed significant increases of nitrogen content only at the highest dose of silicate. Foliar micronutrients, Si concentrations, and plant height were not affected by any of the silicate doses. However, the dose of 400 kg ha<sup>-1</sup> of silicate increased the trichome size, which in turn raised artemisinin concentration in leaves and the infusion. In contrast, the 800 and 1600 kg ha<sup>-1</sup> doses dramatically decreased artemisinin concentration. HeLa cell treatment with the infusion of <italic>A. annua</italic> grown in soil treated with 400 kg ha<sup>-1</sup> of silicate decreased parasite proliferation in a dose-dependent manner when the treatment was carried out after or along with <italic>T. gondii</italic> infection. However, this effect was similar to <italic>A. annua</italic> grown in soil without silicate treatment. Thus, it can be concluded that, even though Si applied to the soil at 400 kg ha<sup>-1</sup> has a positive effect on the <italic>A. annua</italic> glandular trichome size and the artemisinin concentration, this outcome cannot be directly associated with the efficiency of <italic>A. annua</italic> infusion on <italic>T. gondii</italic> growth, suggesting that other components from <italic>A. annua</italic> leaves could be acting in synergy with artemisinin.</p>