School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2000, South Africa.
Sydney Brenner Institute for Molecular Biosciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.
Sci Rep. 2020 Nov 25;10(1):20539. doi: 10.1038/s41598-020-77598-7.
Dichapetalum cymosum produces the toxic fluorinated metabolite, fluoroacetate, presumably as a defence mechanism. Given the rarity of fluorinated metabolites in nature, the biosynthetic origin and function of fluoroacetate have been of particular interest. However, the mechanism for fluorination in D. cymosum was never elucidated. More importantly, there is a severe lack in knowledge on a genetic level for fluorometabolite-producing plants, impeding research on the subject. Here, we report on the first transcriptome for D. cymosum and investigate the wound response for insights into fluorometabolite production. Mechanical wounding studies were performed and libraries of the unwounded (control) and wounded (30 and 60 min post wounding) plant were sequenced using the Illumina HiSeq platform. A combined reference assembly generated 77,845 transcripts. Using the SwissProt, TrEMBL, GO, eggNOG, KEGG, Pfam, EC and PlantTFDB databases, a 69% annotation rate was achieved. Differential expression analysis revealed the regulation of 364 genes in response to wounding. The wound responses in D. cymosum included key mechanisms relating to signalling cascades, phytohormone regulation, transcription factors and defence-related secondary metabolites. However, the role of fluoroacetate in inducible wound responses remains unclear. Bacterial fluorinases were searched against the D. cymosum transcriptome but transcripts with homology were not detected suggesting the presence of a potentially different fluorinating enzyme in plants. Nevertheless, the transcriptome produced in this study significantly increases genetic resources available for D. cymosum and will assist with future research into fluorometabolite-producing plants.
双距翠雀花会产生有毒的含氟代谢物——氟乙酸盐，这可能是一种防御机制。鉴于自然界中含氟代谢物的稀有性，氟乙酸盐的生物合成来源和功能一直是特别关注的问题。然而，双距翠雀花中的氟化机制从未被阐明。更重要的是，对于产生含氟代谢物的植物，在遗传水平上的知识严重缺乏，这阻碍了对该主题的研究。在这里，我们报道了双距翠雀花的第一个转录组，并研究了创伤反应，以深入了解含氟代谢物的产生。进行了机械创伤研究，并使用 Illumina HiSeq 平台对未受伤（对照）和受伤（受伤后 30 和 60 分钟）植物的文库进行测序。生成的组合参考组装产生了 77845 个转录本。使用 SwissProt、TrEMBL、GO、eggNOG、KEGG、Pfam、EC 和 PlantTFDB 数据库，实现了 69%的注释率。差异表达分析显示了 364 个基因对创伤的调控。双距翠雀花的创伤反应包括与信号级联、植物激素调节、转录因子和防御相关的次生代谢物相关的关键机制。然而，氟乙酸盐在诱导性创伤反应中的作用仍不清楚。针对双距翠雀花转录组搜索了细菌氟酶，但未检测到具有同源性的转录本，这表明植物中存在潜在的不同氟化酶。尽管如此，本研究产生的转录组大大增加了双距翠雀花的遗传资源，将有助于未来对产生含氟代谢物的植物的研究。
