中药材青蒿（Artemisia annua）是生产抗疟药物青蒿素的唯一天然来源。青蒿素生物合成的调控是相关领域的研究热点之一，但低温诱导青蒿素生物合成的分子机制不明。我们发现1个响应0℃/ABA的青蒿转录因子AabHLH106，能间接转录激活青蒿素生物合成基因；能与激酶AaAPK1和转录因子AaMYC2相互作用；过表达AabHLH106能提高青蒿素含量和增强耐受低温胁迫能力。在现有基础上，综合采用分子生物学、生物化学和转基因等方法技术深入研究：AaAPK1磷酸化AabHLH106的机制；磷酸化对AabHLH106 转录激活功能的影响；AabHLH106-AaMYC2复合体共同调控青蒿素生物合成的机制。通过本项目研究，结合我们已投稿AabHLH112相关研究，解析低温诱导青蒿素生物合成的分子机制，丰富植物萜类生物合成调控的知识体系，创制出青蒿素含量高且耐受低温胁迫的青蒿新种质。

Artemisia annua is the only natural source for the commercial production of anti-malarial artemisinin. Molecular regulation of artemisinin biosynthesis is one of the hot topics in the field of metabolic regulation on plant secondary metabolism. Unfortunately, it is very poorly understood that low temperature regulates artemisinin biosynthesis at the molecular and biochemical levels. We have identified a bHLH transcription factor (AabHLH106) from A. annua. AabHLH106 was induced by ABA and a low temperature of 0℃, respectively. AabHLH106 was able to indirectly transactivate artemisinin biosynthesis genes, and physically interacted with the kinase AaAPK1 and the transcription factor AaMYC2. Overexpression of AabHLH106 promoted the artemisinin production and enhanced tolerance to low temperature stress in the plants of A. annua. Based on these results, the molecular mechanisms of AabHLH106 regulating artemisinin biosynthesis will be further studied in this project, using the methods associated with molecular biology, biochemistry, transgenic technology and etc. In the presently proposed studies, we focus on the following scientific problems: 1) the molecular mechanism on phosphorylation of AabHLH106 through AaAPK1, 2) the effects of AabHLH106 phosphorylation on transactiviting artemisinin biosynthesis genes, 3) the molecular mechanisms that the AabHLH106-AaMYC2 complex regulates artemisinin biosynthesis. Based on these studies in this project, and combined with a submitted manuscript reported that AabHLH112 is a positive role in regulating artemisinin biosynthesis under low temperature (4℃) condition, molecular mechanisms on low temperature inducing artemisinin biosynthesis is able to be well elucidated. This project not only enriches our knowledge on molecular regulation of terpene biosynthesis in planta, but also establish novel germplasm of A. annua with high-yield artemisinin and strong tolerance to cold stress.