Abstract
Artemisinin is an effective antimalarial sesquiterpene lactone synthesized in
Artemisia annua
. Various transcription factors have been previously reported that can influence the biosynthesis of artemisinin; however, the effect of YABBY family transcription factors on artemisinin biosynthesis was unknown. In the present study, we cloned and characterized AaYABBY5: a homolog of MsYABBY5 in
Mentha spicata
which is involved in modulating the monoterpenes, as a positive regulator of artemisinin biosynthesis in
A. annua
. AaYABBY5 was found localized to the nucleus, and its expression was found to be induced by exogenous methyl jasmonic acid (MeJA) treatment. In the dual-luciferase reporter assay, it was found that AaYABBY5 significantly increased the activities of promoters of amorpha-4,11-diene synthase (
ADS
), cytochrome P450 monooxygenase (
CYP71AV1
), double-bond reductase 2 (
DBR2
), and aldehyde dehydrogenase 1 (
ALDH1
) genes. Yeast one hybrid assay showed that AaYABBY5 directly bonds to the promoters of
CYP71AV1
and
DBR2
genes. Quantitative real-time polymerase chain reaction (qPCR) of
AaYABBY5
overexpression and
AaYABBY5
antisense plants revealed a significant increase in the expression of
ADS
,
CYP71AV1
,
DBR2
, and
ALDH1
in
AaYABBY5
overexpression plants and a significant decrease in the expression of these genes in
AaYABBY5
antisense
A. annua
, respectively. Furthermore, the results of high-performance liquid chromatography (HPLC) showed that the artemisinin and its precursor dihydroartemisinic acid were significantly increased in the
AaYABBY5
overexpression plants while
AaYABBY5
downregulation resulted in a significant decrease in the concentration of artemisinin. Taken together, these results explicitly represent that AaYABBY5 is a positive regulator of artemisinin biosynthesis in
A. annua
.