Plant Biotechnology Division, CSIR-Indian Institute of Integrative Medicine, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, UP, India.
Physiol Plant. 2024 Sep-Oct;176(5):e14581. doi: 10.1111/ppl.14581.
Artemisinin-based combinational therapies (ACTs) constitute the first line of malaria treatment. However, due to its trichome-specific biosynthesis, low concentration, and poor understanding of regulatory mechanisms involved in artemisinin biosynthesis and trichome development, it becomes very difficult to meet the increased demand for ACTs. Here, we have reported that a bHLH transcription factor, AaMYC2-type, plays an important role in regulating GST development and artemisinin biosynthesis in Artemisia annua. AaMYC2-type encodes a protein that is transcriptionally active and localised to the nucleus. It is prominently expressed in aerial parts like leaves, stems, inflorescence and least expressed in roots. AaMYC2-type expression is significantly increased under different hormonal treatments. In transgenic overexpression lines, AaMYC2-type OE, a significant increase in the expression of trichome development and artemisinin biosynthesis genes was observed. While in knockdown lines, Aamyc2-type, expression of trichome development and artemisinin biosynthesis genes were significantly reduced. Yeast one-hybrid assay clearly shows that the AaMYC2-type directly binds to the E-boxes in the promoter regions of ADS and CYP71AVI. The SEM microscopy depicted the number of trichomes elevated from 11 mm in AaMYC2-type OE lines to 6.1 mm in Aamyc2-type. The final effect of the alteration in biosynthetic and trichome developmental genes was observed in the accumulation of artemisinin. In the AaMYC2-type OE, the artemisinin content was 12 mg gDW, which was reduced to 3.2 mg gDW in the Aamyc2-type. Altogether, the above findings suggest that the AaMYC2-type play a dual regulating role in controlling both trichome developmental and artemisinin biosynthetic genes.
基于青蒿素的联合疗法（ACT）是治疗疟疾的一线药物。然而，由于其毛状体特异性生物合成、浓度低以及对青蒿素生物合成和毛状体发育相关调控机制的了解不足，因此很难满足对 ACT 的需求增长。在这里，我们报道了一个 bHLH 转录因子，AaMYC2 型，在调控青蒿素生物合成和毛状体发育中发挥重要作用。AaMYC2 型编码一种转录活性蛋白，并定位于细胞核。它在叶片、茎、花序等地上部分表达明显，在根部表达最少。不同激素处理下 AaMYC2 型的表达显著增加。在转基因过表达系中，AaMYC2 型 OE，毛状体发育和青蒿素生物合成基因的表达显著增加。而在敲低系中，AaMYC2 型的表达，毛状体发育和青蒿素生物合成基因的表达显著降低。酵母单杂交实验清楚地表明，AaMYC2 型直接结合 ADS 和 CYP71AVI 启动子区域的 E 盒。SEM 显微镜描绘了毛状体的数量从 AaMYC2 型 OE 系的 11mm 增加到 Aamyc2 型的 6.1mm。在生物合成和毛状体发育基因的改变的最终影响是青蒿素的积累。在 AaMYC2 型 OE 中，青蒿素含量为 12mg·gDW，在 Aamyc2 型中减少到 3.2mg·gDW。总之，上述发现表明 AaMYC2 型在控制毛状体发育和青蒿素生物合成基因方面发挥双重调节作用。
