The role of CCoAOMT1 and COMT1 in Arabidopsis anthers
The role of CCoAOMT1 and COMT1 in Arabidopsis anthers
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DOI：
10.1007/s00425-011-1586-6
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发表时间：
2012-07-01
期刊：
影响因子：
4.3
通讯作者：
Vogt, Thomas
中科院分区：
文献类型：
--
作者：
Fellenberg, Christin;van Ohlen, Maike;Vogt, Thomas
拟南芥咖啡酰辅酶A依赖的O-甲基转移酶1(CCoAOMT1)和咖啡酸O-甲基转移酶1(COMT1)具有相似的底物谱，但具有不同的底物选择性，被认为是木质素单体针叶醇和芥子醇生物合成中的关键甲基转移酶(OMTs)。虽然CCoAOMT1对咖啡酰辅酶A表现出强烈的偏好，但COMT1优先甲基化5-羟基阿魏酰辅酶A衍生物，并执行黄酮醇与邻近的芳香族二羟基的甲基化反应，如栎素。基于不同的基因敲除系、酚类图谱和免疫组织化学，我们提出了两种酶在拟南芥花药中执行不同但不同任务的证据。CCoAOMT1除了在维管组织中的作用外，还可以定位于年轻雄蕊的绒毛膜，促进亚精胺苯丙烷类化合物的生物合成。COMT1虽然存在于同一器官中，但不定位于绒毡层，而定位于雄蕊的两个直接相邻的细胞层，即药室内层和表皮层。COMT1植物的体内定位和酚类特征提供了证据，COMT1既不有助于亚精胺苯丙烷类结合物的积累，也不有助于花粉粒中黄酮醇的糖苷模式。
Arabidopsis caffeoyl coenzyme A dependent O-methyltransferase 1 (CCoAOMT1) and caffeic acid O-methyltransferase 1 (COMT1) display a similar substrate profile although with distinct substrate preferences and are considered the key methyltransferases (OMTs) in the biosynthesis of lignin monomers, coniferyl and sinapoylalcohol. Whereas CCoAOMT1 displays a strong preference for caffeoyl coenzyme A, COMT1 preferentially methylates 5-hydroxyferuloyl CoA derivatives and also performs methylation of flavonols with vicinal aromatic dihydroxy groups, such as quercetin. Based on different knockout lines, phenolic profiling, and immunohistochemistry, we present evidence that both enzymes fulfil distinct, yet different tasks in Arabidopsis anthers. CCoAOMT1 besides its role in vascular tissues can be localized to the tapetum of young stamens, contributing to the biosynthesis of spermidine phenylpropanoid conjugates. COMT1, although present in the same organ, is not localized in the tapetum, but in two directly adjacent cells layers, the endothecium and the epidermal layer of stamens. In vivo localization and phenolic profiling of comt1 plants provide evidence that COMT1 neither contributes to the accumulation of spermidine phenylpropanoid conjugates nor to the flavonol glycoside pattern of pollen grains.