The jasmonate‐responsive Aa<scp>MYC</scp>2 transcription factor positively regulates artemisinin biosynthesis in <i>Artemisia annua</i>

<jats:title>Summary</jats:title><jats:p> <jats:list list-type="bullet"> <jats:list-item><jats:p>The plant <jats:italic>Artemisia annua</jats:italic> is well known due to the production of artemisinin, a sesquiterpene lactone that is widely used in malaria treatment. Phytohormones play important roles in plant secondary metabolism, such as jasmonic acid (<jats:styled-content style="fixed-case">JA</jats:styled-content>), which can induce artemisinin biosynthesis in <jats:italic>A. annua</jats:italic>. Nevertheless, the <jats:styled-content style="fixed-case">JA</jats:styled-content>‐inducing mechanism remains poorly understood.</jats:p></jats:list-item> <jats:list-item><jats:p>The expression of gene <jats:italic>Aa<jats:styled-content style="fixed-case">MYC</jats:styled-content>2</jats:italic> was rapidly induced by <jats:styled-content style="fixed-case">JA</jats:styled-content> and Aa<jats:styled-content style="fixed-case">MYC</jats:styled-content>2 binds the G‐box‐like motifs within the promoters of gene <jats:italic><jats:styled-content style="fixed-case">CYP</jats:styled-content>71<jats:styled-content style="fixed-case">AV</jats:styled-content>1</jats:italic> and <jats:italic><jats:styled-content style="fixed-case">DBR</jats:styled-content>2</jats:italic>, which are key structural genes in the artemisinin biosynthetic pathway.</jats:p></jats:list-item> <jats:list-item><jats:p>Overexpression of <jats:italic>Aa<jats:styled-content style="fixed-case">MYC</jats:styled-content>2</jats:italic> in <jats:italic>A. annua</jats:italic> significantly activated the transcript levels of <jats:italic><jats:styled-content style="fixed-case">CYP</jats:styled-content>71<jats:styled-content style="fixed-case">AV</jats:styled-content>1</jats:italic> and <jats:italic><jats:styled-content style="fixed-case">DBR</jats:styled-content>2</jats:italic>, which resulted in an increased artemisinin content. By contrast, artemisinin content was reduced in the <jats:styled-content style="fixed-case">RNA</jats:styled-content>i transgenic <jats:italic>A. annua</jats:italic> plants in which the expression of <jats:italic>Aa<jats:styled-content style="fixed-case">MYC</jats:styled-content>2</jats:italic> was suppressed. Meanwhile, the <jats:styled-content style="fixed-case">RNA</jats:styled-content>i transgenic <jats:italic>A. annua</jats:italic> plants showed lower sensitivity to methyl jasmonate treatment than the wild‐type plants.</jats:p></jats:list-item> <jats:list-item><jats:p>These results demonstrate that Aa<jats:styled-content style="fixed-case">MYC</jats:styled-content>2 is a positive regulator of artemisinin biosynthesis and is of great value in genetic engineering of <jats:italic>A. annua</jats:italic> for increased artemisinin production.</jats:p></jats:list-item> </jats:list> </jats:p>