Seasonal variations of artemisinin and its biosynthetic precursors in tetraploid Artemisia annua plants compared with the diploid wild-type

Using colchicine we induced tetraploidy in Artemisia annua L. plants. Durin g a vegetation period we monitored the time course of the levels of artemis inin, its direct precursors, the biosynthetically related sesquiterpenes an d the essential oil content in the diploid (wild-type) and tetraploid A. an nua plants. The averaged artemisinin level in tetraploids was 38% higher th an that of the wild-type as measured over the whole vegetation period. In c ontrast, the averaged essential oil content of the tetraploids over this pe riod was 32% lower. This might suggest a reciprocal correlation between art emisinin (sesquiterpenes) and the essential oil content (monoterpenes). The averaged biomass of the leaves of the tetraploid plants was lower compared to the wild-type plants. Therefore, the artemisinin yield per m(2) tetrapl oids was decreased by 25%. Although the tetraploid plants were smaller than the wild-type plants, certain individual organs like the leaves were consi derably larger, and seeds obtained by cross pollination between tetraploid A. annua plants had a spectacular size. In principle, tetraploid A. annua c an be a useful starting material for a breeding program in order to obtain larger and faster growing plants, which produce higher levels of artemisini n.