Iris (Iris germanica) is a very popular ornamental plant and is known for the precious spice irone produced from its roots. Many iris varieties can also release fragrances through their flowers. However, the composition of iris aroma and the molecular mechanism of its synthesis have not been reported. In this study, we analyzed the volatile floral compounds of I. germanica ‘Harvest of Memories’ at different stages and in different tissues through headspace solid-phase microextraction gas chromatography-mass spectrometry. A total of 36 volatile compounds were identified, and linalool was the dominant component. Transcriptome analysis showed that 35 differentially expressed genes and 218 differentially expressed transcription factors were positively correlated with linalool release. According to the results of qRT-qPCR, the expression level of the IgTPS14 gene was consistent with the release trend of linalool, suggesting that IgTPS14 may play a certain role in linalool synthesis. Phylogenetic analysis showed that the IgTPS14 protein belonged to the TPS-g subfamily. An in vitro enzymatic assay of IgTPS14 and its transient and stable overexpression in tobacco indicated that this gene produced linalool. The transient silencing of IgTPS14 in petals by virus-induced gene silencing technology revealed a significant reduction in the release of linalool. These results will help explore and reveal the molecular mechanism of monoterpenoid synthesis and provide a certain reference for studying the formation of iris aroma.

中文翻译：

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德国鸢尾“记忆的收获”花香生物合成的转录组分析和 IgTPS14 基因的功能表征


鸢尾（德国鸢尾）是一种非常受欢迎的观赏植物，以其根部产生的珍贵香料鸢尾而闻名。许多鸢尾品种还可以通过花朵释放香味。然而，鸢尾香气的组成及其合成的分子机制尚未见报道。在本研究中，我们通过顶空固相微萃取气相色谱-质谱联用技术分析了德国“回忆的收获”在不同阶段和不同组织中的挥发性花卉化合物。共鉴定出36种挥发性成分，其中芳樟醇为主要成分。转录组分析显示，35个差异表达基因和218个差异表达转录因子与芳樟醇释放呈正相关。 qRT-qPCR结果显示，IgTPS14基因的表达水平与芳樟醇的释放趋势一致，提示IgTPS14可能在芳樟醇的合成中发挥一定的作用。系统发育分析表明IgTPS14蛋白属于TPS-g亚家族。 IgTPS14 的体外酶测定及其在烟草中瞬时和稳定的过度表达表明该基因产生芳樟醇。通过病毒诱导的基因沉默技术短暂沉默花瓣中的 IgTPS14，结果表明芳樟醇的释放显着减少。这些结果将有助于探索和揭示单萜合成的分子机制，为研究鸢尾香气的形成提供一定的参考。