Flowers are essential but vulnerable plant organs, exposed to pollinators and florivores; however, flower chemical defenses are rarely investigated. We show here that two clustered terpene synthase and cytochrome P450 encoding genes (TPS11 and CYP706A3) on chromosome 5 of Arabidopsis (Arabidopsis thaliana) are tightly coexpressed in floral tissues, upon anthesis and during floral bud development. TPS11 was previously reported to generate a blend of sesquiterpenes. By heterologous coexpression of TPS11 and CYP706A3 in yeast (Saccharomyces cerevisiae) and Nicotiana benthamiana, we demonstrate that CYP706A3 is active on TPS11 products and also further oxidizes its own primary oxidation products. Analysis of headspace and soluble metabolites in cyp706a3 and 35S:CYP706A3 mutants indicate that CYP706A3-mediated metabolism largely suppresses sesquiterpene and most monoterpene emissions from opening flowers, and generates terpene oxides that are retained in floral tissues. In flower buds, the combined expression of TPS11 and CYP706A3 also suppresses volatile emissions and generates soluble sesquiterpene oxides. Florivory assays with the Brassicaceae specialist Plutella xylostella demonstrate that insect larvae avoid feeding on buds expressing CYP706A3 and accumulating terpene oxides. Composition of the floral microbiome appears also to be modulated by CYP706A3 expression. TPS11 and CYP706A3 simultaneously evolved within Brassicaceae and form the most versatile functional gene cluster described in higher plants so far.plantcell;31/12/2947/FX1F1fx1.

中文翻译：

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混杂的 CYP706A3 减少拟南芥花的萜烯挥发物排放，影响食花动物和花卉微生物组。

花是重要但脆弱的植物器官，暴露于传粉者和食花动物的影响下；然而，很少有人研究花卉的化学防御。我们在此表明​​，拟南芥（Arabidopsis thaliana）5号染色体上的两个簇状萜烯合酶和细胞色素P450编码基因（TPS11和CYP706A3）在开花时和花芽发育期间在花组织中紧密共表达。此前有报道称 TPS11 会生成倍半萜烯混合物。通过在酵母（酿酒酵母）和本塞姆氏烟草中异源共表达 TPS11 和 CYP706A3，我们证明 CYP706A3 对 TPS11 产物具有活性，并且还进一步氧化其自身的初级氧化产物。对 cyp706a3 和 35S:CYP706A3 突变体顶空和可溶性代谢物的分析表明，CYP706A3 介导的代谢很大程度上抑制了开放花中倍半萜和大多数单萜的排放，并产生保留在花组织中的萜氧化物。在花蕾中，TPS11 和 CYP706A3 的联合表达也会抑制挥发性物质的排放并产生可溶性倍半萜氧化物。对十字花科专家小菜蛾进行的花香测定表明，昆虫幼虫避免以表达 CYP706A3 的芽为食并积累萜氧化物。花微生物组的组成似乎也受到 CYP706A3 表达的调节。TPS11 和 CYP706A3 在十字花科内同时进化，并形成迄今为止在高等植物中描述的最通用的功能基因簇。plantcell;31/12/2947/FX1F1fx1。