Abstract：
Sinopodophyllum hexandrum (Royle) T. S. Ying, an important source of podophyllotoxin (PTOX), has become a rare and endangered plant because of over-harvesting. Somatic embryogenesis (SE) is the main way of seedling rapid propagation and germplasm enhancement, but the regeneration of S. hexandrum has not been well established, and the PTOX biosynthesis abilities at different SE stages remain unclear. Therefore, it is extremely important to elucidate the SE mechanism of S. hexandrum and clarify the biosynthesis variation of PTOX. In this study, the transcriptomes of S. hexandrum at different SE stages were sequenced, the contents of PTOX and 4\'-demethylepipodophyllotoxin were assayed, and the transcript expression patterns were validated by qRT-PCR. The results revealed that plant hormone (such as auxins, abscisic acid, zeatin, and gibberellins) related pathways were significantly enriched among different SE stages, indicating these plant hormones play important roles in SE of S. hexandrum; the expression levels of a series of PTOX biosynthesis related genes as well as PTOX and 4\'-demethylepipodophyllotoxin contents were much higher in embryogenic callus stage than in the other stages, suggesting embryogenic callus stage has the best PTOX biosynthesis ability among different SE stages. This study will contribute to germplasm conservation and fast propagation of S. hexandrum, and facilitate the production of PTOX.
摘要：
中华鬼兰（Royle）T.S.Ying，鬼臼毒素（PTOX）的重要来源，由于过度收获，已经成为一种珍稀濒危植物。体细胞胚发生(SE)是幼苗快速繁殖和种质改良的主要途径,但是Hexandrum的再生还没有得到很好的证实，不同SE阶段的PTOX生物合成能力尚不清楚。因此,阐明六甘草的SE机制和阐明PTOX的生物合成变异极为重要。在这项研究中,对不同SE阶段的六角形链球菌转录组进行测序，测定了PTOX和4'-去甲基吡虫啉的含量，并通过qRT-PCR验证转录本的表达模式。结果表明，植物激素(如生长素、脱落酸，zeatin,赤霉素)相关通路在不同SE阶段显著富集，表明这些植物激素在六雄酵母SE中起着重要作用；胚性愈伤组织中一系列与PTOX生物合成相关的基因的表达水平以及PTOX和4'-去甲基吡虫啉毒素含量远高于其他阶段，表明胚性愈伤组织阶段在不同SE阶段中具有最佳的PTOX生物合成能力。本研究将有助于六角形的种质资源保存和快速繁殖。促进PTOX的生产。
