Abstract:

Artemisinin is an important sesquiterpene lactone endoperoxide which is isolated from Chinese medicinal plants Artemisia annua L.. Artemisinin-based combination therapies (ACTs) are recommended as the best treatment for malaria. However, the content of artemisinin in A. annua is low (0.01%~1% of dry weight). Light is a crucial physical factor for plant growth and development. More importantly, it is a significant regulator in the biosynthesis of secondary metabolites. Several studies show that light could regulate the biosynthesis of artemisinin, but its regulatory mechanism is still unknown. According to analysis of a large set of RNA sequencing (RNA-Seq) data of A. annua with red light (40 μmol/m2·s) treatment, AaBPF1, one MYB transcription factor, was screened. The AaBPF1 gene contained a 1 932 bp open reading frame, which encoded a protein with 643 amino acids, and its expression level was induced by red light. The expression pattern of AaBPF1 was similar to those of synthase genes for artemisinin. Subsequently, the expression of synthase genes for artemisinin was detected by Dual-Luciferase Reporter Assay System, and the expression of the target genes and the content of artemisinin in transgenic A. annua plants were analyzed. The results showed that AaBPF1 could significantly activate the expression of ADS and CYP71AV1. The study demonstrated that the transcription factor AaBPF1 might positively regulate the biosynthesis of artemisinin by activating the expression of synthase genes for artemisinin.

Key words: Artemisia annua L., red light, transcription factors, artemisinin

摘要：

青蒿素是一种从中国传统中草药青蒿（Artemisia annua L.）中分离的含有过氧基团的倍半萜内酯类化合物，青蒿素(artemisinin)及其衍生物是目前治疗效果最好的抗疟药物。但是青蒿中的青蒿素含量较低，仅为叶片干重的0.01%~1%。光作为重要的环境因子不仅影响植物的生长发育，还可调控植物体内次生代谢产物的合成。多项研究表明光能够调控青蒿中青蒿素的合成，但其调控机制尚不清楚。通过分析40 μmol/m2·s红光处理的青蒿转录组数据库，筛选到青蒿MYB类转录因子AaBPF1，其基因全长为1 932 bp，编码643个氨基酸，且其表达量受红光诱导。经分析，AaBPF1基因的表达模式与青蒿素合成酶基因类似。随后，利用双荧光素酶报告系统（Dual-Luciferase Reporter Assay System）对青蒿素合成相关酶基因进行检测，并对转基因青蒿植株中目的基因表达量、青蒿素含量进行分析，结果表明，AaBPF1能够显著激活青蒿素合成酶基因中紫穗槐-4,11-二烯合成酶（amorpha-4,11-diene synthase,ADS）基因和紫穗槐-4,11-二烯氧化酶（amorpha-4,11-diene 12-hydroxylase,CYP71AV1）基因的表达。研究结果表明,转录因子AaBPF1可能通过激活青蒿素合成酶基因的表达来正调控青蒿素的合成。

关键词: 青蒿, 红光, 转录因子, 青蒿素