School of Biology Engineering, Dalian Polytechnic University, Dalian, China; Guangdong Provincial Key Laboratory of Silviculture Protection and Utilization, Guangdong Academy of Forestry, Guangzhou, China.
Guangdong Provincial Key Laboratory of Silviculture Protection and Utilization, Guangdong Academy of Forestry, Guangzhou, China.
Plant Physiol Biochem. 2021 Sep;166:115-127. doi: 10.1016/j.plaphy.2021.05.033. Epub 2021 May 27.
Elicitation is one of the most effective strategies for enhancing plant bioactive compounds, such as triterpenoid saponins. Chitosan gained worldwide attention for biostimulant activity, but little is known about its roles in the elicitation of triterpenoid saponin in medicinal plants. Here, we explored the regulatory network of chitosan on saponin accumulation in hairy root cultures of Psammosilene tunicoides, a valuable medicinal herb known for its pain-relieving properties endemic to China. Compared with control, the highest total saponin accumulation exhibited a 4.55-fold enhancement in hairy roots elicited by 200 mg L chitosan for nine days. High-performance liquid chromatography (HPLC) revealed the yields of quillaic acid, gypsogenin and gypsogenin-3-O-β-D-glucuronopyranoside were significantly increased after chitosan treatments. Moreover, exogenous chitosan application dramatically triggered the reactive oxygen species (ROS) scavenging enzyme activities and nitric oxide (NO) content in hairy roots. Comparative transcriptome analysis from chitosan-treated (1 and 9 d) or control groups revealed that differentially expressed genes (DEGs) were greatly enriched in plant-pathogen interaction and metabolic processes. The transcriptions of candidate DEGs involved in chitosan-elicited saponin metabolism were increased, especially genes encoding antioxidant enzymes (SOD, POD and GR), stress-responsive transcription factors (WRKYs and NACs) and terpenoid biosynthetic enzymes (DXS, GPPS and SE). Taken together, these results indicate that chitosan elicitor promotes triterpenoid saponin biosynthesis by enhancing antioxidant activities, NO production and differential gene expression in P. tunicoides hairy roots.
激发是提高植物生物活性化合物（如三萜皂苷）含量的最有效策略之一。壳聚糖作为生物刺激素的活性引起了全球的关注，但对于其在药用植物三萜皂苷激发中的作用知之甚少。在这里，我们探索了壳聚糖对中国特有的具有止痛特性的药用植物珍珠菜毛状根培养物中皂苷积累的调控网络。与对照相比，用 200mg/L壳聚糖处理 9 天，毛状根中的总皂苷积累量最高增加了 4.55 倍。高效液相色谱（HPLC）显示，在用壳聚糖处理后，奎拉酸、羽扇豆醇和羽扇豆醇-3-O-β-D-吡喃葡萄糖醛酸苷的产量显著增加。此外，外源壳聚糖的应用极大地触发了毛状根中活性氧（ROS）清除酶的活性和一氧化氮（NO）的含量。来自壳聚糖处理（1 和 9 天）或对照组的比较转录组分析表明，差异表达基因（DEGs）在植物-病原体相互作用和代谢过程中得到了极大的富集。壳聚糖激发的皂苷代谢相关候选 DEGs 的转录水平增加，特别是编码抗氧化酶（SOD、POD 和 GR）、应激响应转录因子（WRKY 和 NAC）和三萜生物合成酶（DXS、GPPS 和 SE）的基因。综上所述，这些结果表明壳聚糖激发剂通过增强抗氧化活性、NO 产生和 P. tunicoides 毛状根中的差异基因表达来促进三萜皂苷的生物合成。
