Effect of Development Stage on the Artemisinin Content and the Sequence Characterized Amplified Region (SCAR) Marker of High-Artemisinin Yielding Strains of Artemisia annua L.
Abstract:The effects of development states on the artemisinin content of clone S1 of Artemisia anuua L. grown in a greenhouse were investigated in the present study. The artemisinin content increased gradually during the phase of vegetative growth and reached its highest level at 8－9 mg/g dry weight (DW) when the S1 was 6 months old on a long day (LD) photoperiod. Treatment with 9－18 d of short day (SD) photoperiod resulted in the artemisinin content reaching and being maintained at a higher level (2.059－2.289 mg/g DW), twofold that of control plants and plants of S1 presented at the pro-flower budding and flower-budding stages. The artemisinin content varied in different parts of the plant. The artemisinin content of leaves was higher than that of florets and branches. The artemisinin content in middle leaves was higher than that of bottom leaves, and then top leaves. Different densities of capitate glands (the storage organ of artemisinin) located on the surface of leaves, florets, and branches explained the variations in artemisinin content in these parts of the plant. The correlation coefficient between artemisinin content and density of capitate glands on the surface of different organs was 0.987. The genetic marker for artemisinin content was screened using random amplified polymorphic DNA (RAPD) and sequence characterized amplified region (SCAR) techniques. The random primer OPA15 (5‘‘-TTCCGAACCC-3‘‘) could amplify a specific band of approximately 1 000 bp that was present in all high-artemisinin yielding strains, but absent in all low-yielding strains in three independent replications. This specific band was cloned and its sequence was analyzed. This RAPD marker was converted into a SCAR marker to obtain a more stable marker.（*Author for correspondence. Tel: +86 (0)10 6283 6249; Fax: +86 (0)10 8259
1016; E-mail: hcye@ibcas.ac.cn）