Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur,, H.P.-176061, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-, 201002, India.
BMC Plant Biol. 2021 Sep 9;21(1):414. doi: 10.1186/s12870-021-03172-6.
Adventitious root formation is considered a major developmental step during the propagation of difficult to root plants, especially in horticultural crops. Recently, adventitious roots induced through plant tissue culture methods have also been used for production of phytochemicals such as flavonoids, anthocyanins and anthraquinones. It is rather well understood which horticultural species will easily form adventitious roots, but the factors affecting this process at molecular level or regulating the induction process in in vitro conditions are far less known. The present study was conducted to identify transcripts involved in in vitro induction and formation of adventitious roots using Arnebia euchroma leaves at different time points (intact leaf (control), 3 h, 12 h, 24 h, 3 d, 7 d, 10 d and 15 d). A. euchroma is an endangered medicinal Himalayan herb whose root contains red naphthoquinone pigments. These phytoconstituents are widely used as an herbal ingredient in Asian traditional medicine as well as natural colouring agent in food and cosmetics.
A total of 137.93 to 293.76 million raw reads were generated and assembled to 54,587 transcripts with average length of 1512.27 bps and N50 of 2193 bps, respectively. In addition, 50,107 differentially expressed genes were identified and found to be involved in plant hormone signal transduction, cell wall modification and wound induced mitogen activated protein kinase signalling. The data exhibited dominance of auxin responsive (AUXIN RESPONSE FACTOR8, IAA13, GRETCHEN HAGEN3.1) and sucrose translocation (BETA-31 FRUCTOFURANOSIDASE and MONOSACCHARIDE-SENSING protein1) genes during induction phase. In the initiation phase, the expression of LATERAL ORGAN BOUNDARIES DOMAIN16, EXPANSIN-B15, ENDOGLUCANASE25 and LEUCINE-rich repeat EXTENSION-like proteins was increased. During the expression phase, the same transcripts, with exception of LATERAL ORGAN BOUNDARIES DOMAIN16 were identified. Overall, the transcriptomic analysis revealed a similar patterns of genes, however, their expression level varied in subsequent phases of in vitro adventitious root formation in A. euchroma.
The results presented here will be helpful in understanding key regulators of in vitro adventitious root development in Arnebia species, which may be deployed in the future for phytochemical production at a commercial scale.
不定根的形成被认为是植物繁殖过程中的一个主要发育步骤，尤其是在园艺作物中。最近，通过植物组织培养方法诱导的不定根也被用于生产类黄酮、花青素和蒽醌等植物化学物质。人们已经相当了解哪些园艺物种容易形成不定根，但在分子水平上影响这一过程的因素或调节体外诱导过程的因素知之甚少。本研究旨在使用不同时间点（完整叶片（对照）、3 h、12 h、24 h、3 d、7 d、10 d 和 15 d）的 Arnebia euchroma 叶片，鉴定参与体外诱导和不定根形成的转录本。A. euchroma 是一种濒危的喜马拉雅药用草本植物，其根含有红色萘醌色素。这些植物成分被广泛用作亚洲传统医学中的草药成分，以及食品和化妆品中的天然着色剂。
共产生了 13793 到 2937600000 条原始reads，组装成 54587 个转录本，平均长度为 1512.27 bp，N50 为 2193 bp。此外，鉴定出 50107 个差异表达基因，它们参与植物激素信号转导、细胞壁修饰和创伤诱导的丝裂原活化蛋白激酶信号转导。数据显示，在诱导阶段，生长素反应（AUXIN RESPONSE FACTOR8、IAA13、GRETCHEN HAGEN3.1）和蔗糖转运（BETA-31 FRUCTOFURANOSIDASE 和 MONOSACCHARIDE-SENSING protein1）基因占主导地位。在起始阶段，LATERAL ORGAN BOUNDARIES DOMAIN16、EXPANSIN-B15、ENDOGLUCANASE25 和 LEUCINE-RICH REPEAT EXTENSION-like 蛋白的表达增加。在表达阶段，除了 LATERAL ORGAN BOUNDARIES DOMAIN16 外，还鉴定出相同的转录本。总的来说，转录组分析揭示了相似的基因模式，但它们在 A. euchroma 体外不定根形成的后续阶段的表达水平有所不同。
本研究结果将有助于了解 Arnebia 物种体外不定根发育的关键调控因子，这些因子可能在未来用于商业规模的植物化学物质生产。
