Phenylpropanoid polyamine conjugate biosynthesis in Arabidopsis thaliana flower buds
Phenylpropanoid polyamine conjugate biosynthesis in Arabidopsis thaliana flower buds
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DOI：
10.1016/j.phytochem.2009.08.010
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发表时间：
2009-07-01
期刊：
影响因子：
3.8
通讯作者：
Vogt, Thomas
中科院分区：
文献类型：
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作者：
Fellenberg, Christin;Boettcher, Christoph;Vogt, Thomas
已在许多植物物种的花中鉴定出苯丙素多胺缀合物。最近才在拟南芥花蕾和花粉粒中发现它们的存在。对年轻花芽绒毡层特异的阳离子依赖性 O-甲基转移酶 AtTSM1 进行注释和定位，使得随后能够鉴定出在苯丙素多胺缀合物生物合成中具有推定作用的几个基因。基于对几种拟南芥敲除突变体的分析，提出了这些缀合物的生物合成途径，其中涉及由不同阳离子依赖性O-甲基转移酶催化的两个甲基化步骤、细胞色素P450 (CYP98A8)催化的羟基化以及由BAHD-like进行的缀合酰基转移， 羟基肉桂酰（HC）-转移酶。基于 cyp98A8 敲除系的 LC/MS 代谢物分析在相应的花中鉴定出新的阿魏酰基和 4-香豆酰亚精胺缀合物，这与该基因在这些缀合物的羟基化中的作用一致。在野生型以及突变株系中鉴定出少量双酰基亚精胺缀合物和三酰基亚精胺缀合物的模式，可能是其他HC转移酶的产物。在编码后期酶促步骤的基因的敲除或 RNAi 系中观察到了该途径早期基因的转录抑制。讨论了这些发现对拟南芥花蕾中亚精胺结合物生物合成的影响。 (C) 2009 Elsevier Ltd. 保留所有权利。
Phenylpropanoid polyamine conjugates have been identified in flowers of many plant species. Their presence in Arabidopsis thaliana has only been recently established in flower buds and pollen grains. Annotation and location of a cation-dependent O-methyltransferase AtTSM1 specifically to the tapetum of young flower buds enabled the subsequent identification of several genes with a putative role in phenylpropanoid polyamine conjugate biosynthesis. Based on the analysis of several A. thaliana knockout mutants, a biosynthetic pathway of these conjugates is proposed, which involves two methylation steps catalyzed by different cation-dependent O-methyltransferases, a cytochrome P450 (CYP98A8) catalyzed hydroxylation, and a conjugating acyl transfer performed by a BAHD-like, hydroxycinnamoyl (HC)-transferase. LC/MS based metabolite profiling of the cyp98A8 knockout line identified new feruloyl- and 4-coumaroylspermidine conjugates in the corresponding flowers consistent with a role of this gene in the hydroxylation of these conjugates. A pattern of minor amounts of bis- and tris-acylspermidine conjugates, likely the products of additional HC-transferases were identified in wild type as well as in the mutant lines. Transcript suppression of the genes early in the pathway was observed in knockout or RNAi-lines of the genes encoding late enzymatic steps. The implication of these findings for spermidine conjugate biosynthesis in flower buds of A. thaliana is discussed. (C) 2009 Elsevier Ltd. All rights reserved.