Research and Development Center of Chinese Medicine Resources and Biotechnology, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China.
J Integr Plant Biol. 2022 Jun;64(6):1212-1228. doi: 10.1111/jipb.13258. Epub 2022 May 17.
The important antimalarial drug artemisinin is biosynthesized and stored in Artemisia annua glandular trichomes and the artemisinin content correlates with trichome density; however, the factors affecting trichome development are largely unknown. Here, we demonstrate that the A. annua R2R3 MYB transcription factor TrichomeLess Regulator 1 (TLR1) negatively regulates trichome development. In A. annua, TLR1 overexpression lines had 44.7%-64.0% lower trichome density and 11.5%-49.4% lower artemisinin contents and TLR1-RNAi lines had 33%-93.3% higher trichome density and 32.2%-84.0% higher artemisinin contents compared with non-transgenic controls. TLR1 also negatively regulates the expression of anthocyanin biosynthetic pathway genes in A. annua. When heterologously expressed in Arabidopsis thaliana, TLR1 interacts with GLABROUS3a, positive regulator of trichome development, and represses trichome development. Yeast two-hybrid and pull-down assays indicated that TLR1 interacts with the WUSCHEL homeobox (WOX) protein AaWOX1, which interacts with the LEAFY-like transcription factor TLR2. TLR2 overexpression in Arabidopsis and A. annua showed that TLR2 reduces trichome development by reducing gibberellin levels. Furthermore, artemisinin contents were 19%-43% lower in TLR2-overexpressing A. annua plants compared to controls. These data indicate that TLR1 and TLR2 negatively regulate trichome density by lowering gibberellin levels and may enable approaches to enhance artemisinin yields.
重要的抗疟药物青蒿素是在黄花蒿的腺毛中生物合成和储存的，青蒿素的含量与毛状体密度相关；然而，影响毛状体发育的因素在很大程度上尚不清楚。在这里，我们证明黄花蒿 R2R3 MYB 转录因子 TrichomeLess Regulator 1（TLR1）负调控毛状体发育。在黄花蒿中，TLR1 过表达系的毛状体密度降低了 44.7%-64.0%，青蒿素含量降低了 11.5%-49.4%，而 TLR1-RNAi 系的毛状体密度增加了 33%-93.3%，青蒿素含量增加了 32.2%-84.0%，与非转基因对照相比。TLR1 还负调控黄花蒿中花青素生物合成途径基因的表达。当在拟南芥中异源表达时，TLR1 与 GLABROUS3a 相互作用，后者是毛状体发育的正调控因子，并抑制毛状体发育。酵母双杂交和 pull-down 实验表明，TLR1 与 WUSCHEL 同源盒（WOX）蛋白 AaWOX1 相互作用，而 AaWOX1 与 LEAFY 类转录因子 TLR2 相互作用。在拟南芥和黄花蒿中过表达 TLR2 表明，TLR2 通过降低赤霉素水平来减少毛状体发育。此外，与对照相比，TLR2 过表达的黄花蒿植株的青蒿素含量降低了 19%-43%。这些数据表明，TLR1 和 TLR2 通过降低赤霉素水平来负调控毛状体密度，这可能为提高青蒿素产量提供方法。
