Search

Amorpha-4,11-diene synthase (ADS) is the first key enzyme of artemisinin biosynthetic pathway in Artemisia annua L. In this study, the promoter region of the ADS gene has been cloned and used to demonstrate the expression of GUS reporter gene in both glandular trichomes of A. annua and non-glandular trichomes of Arabidopsis thaliana following homologous and heterologous expression of ADS promoter- GUS fusion. Subsequently, 5′ sequential deletion analysis of the ADS promoter revealed that a short sequence, −350 upstream of the transcription start site, was sufficient for trichome-specific expression in A. thaliana and that the region from −350 to −300 contained essential elements for this observed specificity. However, frequencies of transgenic A. thaliana plants displaying trichome-specific expressions varied between different lines, and all the lines with deleted fragments of the ADS promoter showed lower frequencies than the line with full-length ADS promoter. Most lines with deleted ADS promoter- GUS fusions showed GUS expressions in the guard cells of stomata as well, which was not observed in A. thaliana plants transformed with the full-length ADS promoter. GUS activities varied among different transgenic lines as well, both in transiently transformed Nicotiana benthamiana and stably transformed A. thaliana, with promoter-deletion lines exhibiting higher GUS activities than the full-length ADS promoter line. [ABSTRACT FROM AUTHOR]

emisinin is currently the best therapeutic against both drug-resistant and cerebral-malaria-causing strains of Plasmodium falciparum. Allene oxide cyclase (AOC) is the key enzyme in the biosynthetic pathway of jasmonates. In this study, a full-length cDNA of AOC gene (named as AaAOC) was cloned from Artemisia annua L. AaAOC was 1,007 bp, containing an open reading frame (750 bp) encoding 249 amino acids. Comparative and bioinformatic analyses revealed that the deduced protein of AaAOC was highly homologous to AOC from other plant species. Phylogenetic analysis indicated that AaAOC was clustered in a closely related subgroup with AOC of Camptotheca acuminata. Southern blot analysis revealed that AaAOC was a multicopy gene. Reverse transcriptase-polymerase chain reaction (RT-PCR) and QPCR analysis showed that AaAOC mRNA accumulated most abundantly in alabastrums, in which the content of artemisinin was previously proven to be the highest. RT-PCR analysis revealed that MeJA, ABA, and ethylene treatments significantly enhanced AaAOC transcript expression. And the results of HPLC showed that the contents of artemisinin were greatly increased after the treatments of ABA and MeJA. [ABSTRACT FROM AUTHOR]