Gene Coexpression Analysis Reveals Complex Metabolism of the Monoterpene Alcohol Linalool in Arabidopsis Flowers
Gene Coexpression Analysis Reveals Complex Metabolism of the Monoterpene Alcohol Linalool in Arabidopsis Flowers
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DOI：
10.1105/tpc.113.117382
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发表时间：
2013-11-01
期刊：
影响因子：
11.6
通讯作者：
Werck-Reichhart, Daniele
中科院分区：
文献类型：
--
作者：
Ginglinger, Jean-Francois;Boachon, Benoit;Werck-Reichhart, Daniele
细胞色素 P450 家族包含植物代谢中最大的酶家族，其许多成员在拟南芥中的功能仍然未知。基因共表达分析指出，两个 P450 在花中与两个单萜合酶共表达，因此预计参与单萜代谢。我们发现所有四个选定的基因，两种萜烯合酶（TPS10和TPS14）和两种细胞色素P450（CYP71B31和CYP76C3），在开花时同时表达，主要在上部花药丝和花瓣中。在本塞姆氏烟草中瞬时表达后，TPS 酶共定位于与质体表面相关的囊泡结构中，而 P450 蛋白在内质网中检测到。无论它们是在酿酒酵母还是在本塞姆氏烟草中表达，TPS酶都会形成两种不同的芳樟醇对映体：TPS10的(-)-(R)-芳樟醇和TPS14的(+)-(S)-芳樟醇。两种 P450 酶均代谢两种芳樟醇对映体，形成不同但重叠的羟基化或环氧化产物组。这些氧化产物不会排放到花的顶部空间，而是作为进一步转化或结合的代谢物积聚在花组织中。这项工作揭示了拟南芥花中复杂的芳樟醇代谢，其生态作用仍有待确定。
The cytochrome P450 family encompasses the largest family of enzymes in plant metabolism, and the functions of many of its members in Arabidopsis thaliana are still unknown. Gene coexpression analysis pointed to two P450s that were coexpressed with two monoterpene synthases in flowers and were thus predicted to be involved in monoterpenoid metabolism. We show that all four selected genes, the two terpene synthases (TPS10 and TPS14) and the two cytochrome P450s (CYP71B31 and CYP76C3), are simultaneously expressed at anthesis, mainly in upper anther filaments and in petals. Upon transient expression in Nicotiana benthamiana, the TPS enzymes colocalize in vesicular structures associated with the plastid surface, whereas the P450 proteins were detected in the endoplasmic reticulum. Whether they were expressed in Saccharomyces cerevisiae or in N. benthamiana, the TPS enzymes formed two different enantiomers of linalool: (-)-(R)- linalool for TPS10 and (+)-(S)- linalool for TPS14. Both P450 enzymes metabolize the two linalool enantiomers to form different but overlapping sets of hydroxylated or epoxidized products. These oxygenated products are not emitted into the floral headspace, but accumulate in floral tissues as further converted or conjugated metabolites. This work reveals complex linalool metabolism in Arabidopsis flowers, the ecological role of which remains to be determined.