Identification of an Arabidopsis Fatty Alcohol: Caffeoyl-Coenzyme A Acyltransferase Required for the Synthesis of Alkyl Hydroxycinnamates in Root Waxes
Identification of an Arabidopsis Fatty Alcohol: Caffeoyl-Coenzyme A Acyltransferase Required for the Synthesis of Alkyl Hydroxycinnamates in Root Waxes
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DOI：
10.1104/pp.112.201822
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发表时间：
2012-09-01
期刊：
影响因子：
7.4
通讯作者：
Pollard, Mike
中科院分区：
文献类型：
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作者：
Kosma, Dylan K.;Molina, Isabel;Pollard, Mike
木栓素是一种不溶性的杂聚物，但用氯仿快速浸根可提取出大量可溶性脂类。这些提取物包括饱和长链伯醇和羟基肉桂酸的酯。这种脂肪醇和羟基肉桂酸也存在于木栓质中。我们表明，烷基香豆酸和咖啡酸，这是拟南芥（拟南芥）根蜡的主要成分，主要存在于主根。以前我们鉴定了脂族木栓素阿魏酰转移酶（At 5g 41040），一种HXXXD型酰基转移酶（BAHD家族），负责将阿魏酸掺入拟南芥脂族木栓素中。然而，脂肪族木栓素阿魏酸转移酶突变体的烷基羟基肉桂酸酯根蜡组合物不受影响。在这里，我们确定了一个密切相关的基因At 5g 63560，负责合成羟基肉桂酸烷基酯的一个子集（咖啡酸烷基酯）。携带P-At 5g 63560：：YFP融合体的转基因植物在栓化组织中表现出转录活性。At 5g 63560的敲除突变体的咖啡酸烷基酯含量严重降低，但香豆酸烷基酯含量不降低。重组At 5g 63560 p在与咖啡酰辅酶A（CoA）底物一起存在时具有更高的酰基转移酶活性，因此我们将该酰基转移酶命名为脂肪醇：咖啡酰辅酶A咖啡酰转移酶。应力实验表明，NaCl处理的野生型和脂肪醇：咖啡酰辅酶A咖啡酰转移酶植物的根蜡香豆酸烷基酯含量升高。我们进一步证明了脂肪酰辅酶A还原酶（法尔斯）FAR 5（At 3g 44550）、FAR 4（At 3g 44540）和FAR 1（At 5g 22500）分别是合成C18、C20和C22烷基羟基肉桂酸酯所需的。总的来说，这些结果表明，多个酰基转移酶被用于合成烷基羟基肉桂酸酯的拟南芥根蜡和FAR 1/4/5提供所需的烷基羟基肉桂酸合成的脂肪醇。
While suberin is an insoluble heteropolymer, a number of soluble lipids can be extracted by rapid chloroform dipping of roots. These extracts include esters of saturated long-chain primary alcohols and hydroxycinnamic acids. Such fatty alcohols and hydroxycinnamic acids are also present in suberin. We demonstrate that alkyl coumarates and caffeates, which are the major components of Arabidopsis (Arabidopsis thaliana) root waxes, are present primarily in taproots. Previously we identified ALIPHATIC SUBERIN FERULOYL TRANSFERASE (At5g41040), a HXXXD-type acyltransferase (BAHD family), responsible for incorporation of ferulate into aliphatic suberin of Arabidopsis. However, aliphatic suberin feruloyl transferase mutants were unaffected in alkyl hydroxycinnamate ester root wax composition. Here we identify a closely related gene, At5g63560, responsible for the synthesis of a subset of alkyl hydroxycinnamate esters, the alkyl caffeates. Transgenic plants harboring P-At5g63560::YFP fusions showed transcriptional activity in suberized tissues. Knockout mutants of At5g63560 were severely reduced in their alkyl caffeate but not alkyl coumarate content. Recombinant At5g63560p had greater acyltransferase activity when presented with caffeoyl-Coenzyme A (CoA) substrate, thus we have named this acyltransferase FATTY ALCOHOL: CAFFEOYL-CoA CAFFEOYL TRANSFERASE. Stress experiments revealed elevated alkyl coumarate content in root waxes of NaCl-treated wild-type and fatty alcohol:caffeoyl-CoA caffeoyl transferase plants. We further demonstrate that FATTY ACYL-CoA REDUCTASEs (FARs) FAR5 (At3g44550), FAR4 (At3g44540), and FAR1 (At5g22500) are required for the synthesis of C18, C20, and C22 alkyl hydroxycinnamates, respectively. Collectively, these results suggest that multiple acyltransferases are utilized for the synthesis of alkyl hydroxycinnamate esters of Arabidopsis root waxes and that FAR1/4/5 provide the fatty alcohols required for alkyl hydroxycinnamate synthesis.