Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India.
Biotechnology Division, Central Institute of Medicinal and Aromatic Plants, (CSIR-CIMAP) P.O. CIMAP, Near Kukrail Picnic Spot, Lucknow, 226015, India.
Plant Sci. 2020 Jan;290:110291. doi: 10.1016/j.plantsci.2019.110291. Epub 2019 Oct 1.
A. racemosus is a rich source of pharmacologically active steroidal saponins. Most of the studies are related to its chemistry and pharmacology, but the pathway involved in the biosynthesis of steroidal saponin is not much emphasized. Squalene epoxidase acts as a rate-limiting enzyme in this biosynthesis. In this study, we have selected root specific squalene epoxidase ArSQE from A. racemosus for its characterization. ArSQE was able to complement ergosterol auxotrophy in erg1 yeast mutants. Mutants were sensitive to the antifungal drug terbinafine, whereas ArSQE complementation made them tolerant to the same drug. ArSQE plays a significant role in early germination in transgenic tobacco. The transgenic tobacco seedlings overexpressing ArSQE were tolerant to terbinafine and abiotic stress. Expression analysis of transcripts in ArSQE transgenic lines suggests that it mostly affects ABA, GA, stress, and sterol related functions in transgenic tobacco. Further, root specific MeJA responsive A. racemosus bZIP transcription factors (TFs), ArTGA1 and ArTGA2, were identified that bind to MeJA responsive cis-element present in the promoter region of ArSQE. Characterization of ArSQE of A. racemosus provides new information about its regulation through MeJA responsive bZIP TF along with its role in the development and abiotic stress response in transgenic tobacco.
鸡骨常山是一种富含具有药理活性的甾体皂苷的植物。大多数研究都与它的化学和药理学有关，但甾体皂苷生物合成途径并没有得到太多的重视。鲨烯环氧化酶在该生物合成途径中起着限速酶的作用。在这项研究中，我们从鸡骨常山（A. racemosus）中选择了根特异性的鲨烯环氧化酶 ArSQE 进行其特征描述。ArSQE 能够在 erg1 酵母突变体中补充麦角固醇的营养缺陷。突变体对抗真菌药物特比萘芬敏感，而 ArSQE 的互补作用使它们对相同药物具有耐受性。ArSQE 在转基因烟草的早期萌发中起着重要作用。过表达 ArSQE 的转基因烟草幼苗对特比萘芬和非生物胁迫具有耐受性。ArSQE 转基因系的转录本表达分析表明，它主要影响 ABA、GA、胁迫和固醇相关功能。此外，还鉴定了根特异性的 MeJA 响应鸡骨常山 bZIP 转录因子（TFs）ArTGA1 和 ArTGA2，它们与 ArSQE 启动子区域中存在的 MeJA 响应顺式元件结合。鸡骨常山 ArSQE 的特征描述提供了有关其通过 MeJA 响应 bZIP TF 进行调节的新信息，以及它在转基因烟草发育和非生物胁迫反应中的作用。
