Isolation of high artemisinin-yielding clones of Artemisia annua

Abstract

Abstract A random collection of 700 plants of a seed-raised population of Artemisia annua cv. Asha were screened for morphology and artemisinin and essential oil contents. Four morphologically distinct plant types were detected: short and early flowering, tall and early flowering, tall and late flowering, and dwarf and very late flowering. The artemisinin and essential oil were largely present in the inflorescence of all the types of plants. The artemisinin and the essential oil content in the dried herb (inflorescence + leaves) of these plant types ranged from 0.001 to 0.11% and 0.14 to 0.60%, respectively; the late flowering plants were generally richer in both artemisinin and the essential oil. Eleven individual adult plants were selected on the basis of their high artemisinin yield and in vitro regeneration response to a micropropagation procedure using young inflorescence segments as explants. The micro-cloned progenies of the selected plants were tested for their growth, morphology and artemisinin yield and homology in respect to these characters with the respective parent selections. The parent-micropropagated progeny characteristics were observed to be largely congruent. The artemisinin profiles of the micropropagated progenies at vegetative, preflowering and full bloom stages indicated that while highest artemisinin accumulation occurred at full bloom stage, the artemisinin content at preflowering stage was positively correlated with that at full bloom stage. Among the material cloned in vitro and tested in the field, clone numbers 166 and 187 yield 3.2- and 2.5-fold more artemisinin per plant as compared to the parent cultivar Asha, the former due to high herb yield and latter due to high artemisinin content per se.