Jadaun Jyoti Singh, Sangwan Neelam S, Narnoliya Lokesh K, Singh Neha, Bansal Shilpi, Mishra Bhawana, Sangwan Rajender Singh
Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), Lucknow 226015, India.
Center of Innovative and Applied Bioprocessing (A National Institute under Department of Biotechnology, Govt. of India), C-127, Phase-8, Industrial Area, S.A.S. Nagar, Mohali - 160071, Punjab, India.
Physiol Plant. 2017 Apr;159(4):381-400. doi: 10.1111/ppl.12507. Epub 2016 Oct 25.
Rose-scented geranium (Pelargonium spp.) is one of the most important aromatic plants and is well known for its diverse perfumery uses. Its economic importance is due to presence of fragrance rich essential oil in its foliage. The essential oil is a mixture of various volatile phytochemicals which are mainly terpenes (isoprenoids) in nature. In this study, on the geranium foliage genes related to isoprenoid biosynthesis (DXS, DXR and HMGR) were isolated, cloned and confirmed by sequencing. Further, the first gene of 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway, 1-deoxy-d-xylulose-5-phosphate synthase (GrDXS), was made full length by using rapid amplification of cDNA ends strategy. GrDXS contained a 2157 bp open reading frame that encoded a polypeptide of 792 amino acids having calculated molecular weight 77.5 kDa. This study is first report on heterologous expression and kinetic characterization of any gene from this economically important plant. Expression analysis of these genes was performed in different tissues as well as at different developmental stages of leaves. In response to external elicitors, such as methyl jasmonate, salicylic acid, light and wounding, all the three genes showed differential expression profiles. Further GrDXS was over expressed in the homologous (rose-scented geranium) as well as in heterologous (Withania somnifera) plant systems through genetic transformation approach. The over-expression of GrDXS led to enhanced secondary metabolites production (i.e. essential oil in rose-scented geranium and withanolides in W. somnifera). To the best of our knowledge, this is the first report showing the expression profile of the three genes related to isoprenoid biosynthesis pathways operated in rose-scented geranium as well as functional characterization study of any gene from rose-scented geranium through a genetic transformation system.
玫瑰天竺葵（天竺葵属）是最重要的芳香植物之一，因其在香水制作中的多种用途而闻名。其经济重要性在于其叶片中含有富含香味的精油。该精油是多种挥发性植物化学物质的混合物，其本质上主要是萜类化合物（类异戊二烯）。在本研究中，从天竺葵叶片中分离、克隆并通过测序确认了与类异戊二烯生物合成相关的基因（DXS、DXR和HMGR）。此外，利用cDNA末端快速扩增策略获得了2-C-甲基-D-赤藓糖醇-4-磷酸（MEP）途径的第一个基因1-脱氧-D-木酮糖-5-磷酸合酶（GrDXS）的全长。GrDXS包含一个2157 bp的开放阅读框，编码一个由792个氨基酸组成的多肽，计算分子量为77.5 kDa。本研究是关于这种经济重要植物中任何基因的异源表达和动力学表征的首次报道。对这些基因在不同组织以及叶片不同发育阶段进行了表达分析。响应外部诱导物，如茉莉酸甲酯、水杨酸、光照和创伤，这三个基因均表现出差异表达谱。此外，通过遗传转化方法，GrDXS在同源植物（玫瑰天竺葵）以及异源植物（印度人参）系统中过表达。GrDXS的过表达导致次生代谢产物产量增加（即玫瑰天竺葵中的精油和印度人参中的甾类内酯）。据我们所知，这是首次报道玫瑰天竺葵中与类异戊二烯生物合成途径相关的三个基因的表达谱，以及通过遗传转化系统对玫瑰天竺葵中任何基因的功能表征研究。
