Artemisia annua is a medicinal plant rich in terpenes and flavonoids with useful biological activities such as antioxidant, anticancer, and antimalarial activities. The transcriptional regulation of flavonoid biosynthesis in A. annua has not been well-studied. In this study, we identified a YABBY family transcription factor, AaYABBY5, as a positive regulator of anthocyanin and total flavonoid contents in A. annua. AaYABBY5 was selected based on its similar expression pattern to the phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and flavonol synthase (FLS) genes. A transient dual-luciferase assay in Nicotiana bethamiana with the AaYABBY5 effector showed a significant increase in the activity of the downstream LUC gene, with reporters AaPAL, AaCHS, AaCHI, and AaUFGT. The yeast one-hybrid system further confirmed the direct activation of these promoters by AaYABBY5. Gene expression analysis of stably transformed AaYABBY5 overexpression, AaYABBY5 antisense, and control plants revealed a significant increase in the expression of AaPAL, AaCHS, AaCHI, AaFLS, AaFSII, AaLDOX, and AaUFGT in AaYABBY5 overexpression plants. Moreover, their total flavonoid content and anthocyanin content were also found to increase. AaYABBY5 antisense plants showed a significant decrease in the expression of flavonoid biosynthetic genes, as well as a decrease in anthocyanin and total flavonoid contents. In addition, phenotypic analysis revealed deep purple-pigmented stems, an increase in the leaf lamina size, and higher trichome densities in AaYABBY5 overexpression plants. Together, these data proved that AaYABBY5 is a positive regulator of flavonoid biosynthesis in A. annua. Our study provides candidate transcription factors for the improvement of flavonoid concentrations in A. annua and can be further extended to elucidate its mechanism of regulating trichome development.

中文翻译：

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AaYABBY5对黄花蒿类黄酮生物合成的转录调控

青蒿是一种富含萜烯和类黄酮的药用植物，具有抗氧化、抗癌和抗疟疾等有用的生物活性。黄酮类生物合成的转录调控青蒿没有得到很好的研究。在这项研究中，我们鉴定了一个 YABBY 家族转录因子 AaYABBY5，作为花青素和总黄酮含量的正调节因子青蒿. 选择 AaYABBY5 是基于其与苯丙氨酸解氨酶相似的表达模式（朋友), 查尔酮合酶 (CHS), 查尔酮异构酶 (气) 和黄酮醇合酶 (FLS) 基因。瞬时双荧光素酶测定烟草与 AaYABBY5 效应器的下游活性显着增加卢克基因，与记者AaPAL,AaCHS，阿奇， 和AaUFGT. 酵母单杂交系统进一步证实了 AaYABBY5 对这些启动子的直接激活。稳定转化的基因表达分析AaYABBY5过度表达，AaYABBY5反义植物和对照植物的表达显着增加AaPAL,AaCHS、AaCHI、AaFLS、AaFSII、AaLDOX， 和AaUFGT在AaYABBY5过度表达植物。此外，还发现它们的总黄酮含量和花青素含量也有所增加。AaYABBY5反义植物表现出类黄酮生物合成基因的表达显着降低，以及花青素和总黄酮含量的降低。此外，表型分析显示深紫色的茎，叶片尺寸增加，毛状体密度更高AaYABBY5过度表达植物。总之，这些数据证明 AaYABBY5 是黄酮类生物合成的正调节剂。青蒿. 我们的研究为提高黄酮类化合物浓度提供了候选转录因子青蒿并可以进一步扩展以阐明其调节毛状体发育的机制。