Regulation of CONIFERALDEHYDE 5-HYDROXYLASE expression to modulate cell wall lignin structure in rice
Regulation of CONIFERALDEHYDE 5-HYDROXYLASE expression to modulate cell wall lignin structure in rice
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DOI：
10.1007/s00425-017-2692-x
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发表时间：
2017-08-01
期刊：
影响因子：
4.3
通讯作者：
Umezawa, Toshiaki
中科院分区：
文献类型：
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作者：
Takeda, Yuri;Koshiba, Taichi;Umezawa, Toshiaki
主要结论调控编码针叶醛5-羟基酶的基因导致水稻细胞壁木质素结构发生显著变化，为提高草类生物量的利用提供了一个有前景的基因工程靶标。木质素的芳香组成对木质纤维素类生物质的利用特性有很大影响，因此一直是细胞壁工程研究的主要目标之一。然而，关于单子叶牧草木质素修饰的信息有限，尽管草类木质纤维素在生物燃料生产和各种生物精炼应用中具有巨大的潜力。在这里，我们报道了编码针叶醛5-羟基酶(CAld5H，或阿魏酸5-羟基酶，F5H)的基因的操作导致水稻(Oryza Sativa)的丁香基(S)/愈创木基(G)木质素的芳香组成发生了实质性的变化。在水稻中鉴定的三个CAld5H基因中，OsCAld5H1(CYP84A5)似乎主要在产生木质素的水稻营养组织中表达。一系列湿化学和核磁共振结构分析表明，OsCAld5H1的下调产生了主要富含G单元的木质素变化，而OsCAld5H1的上调导致了木质素在S单元的富含。我们的数据表明，OsCAld5H1的表达是控制S/G木质素在水稻细胞壁中组成的主要因素。鉴于S/G木质素的组成会影响各种生物量的性质，我们认为控制CAld5H基因的表达是一种很有前途的策略，可以将草的生物量提升到生物精炼应用中。
Main conclusion Regulation of a gene encoding coniferaldehyde 5-hydroxylase leads to substantial alterations in lignin structure in rice cell walls, identifying a promising genetic engineering target for improving grass biomass utilization.The aromatic composition of lignin greatly affects utilization characteristics of lignocellulosic biomass and, therefore, has been one of the primary targets of cell wall engineering studies. Limited information is, however, available regarding lignin modifications in monocotyledonous grasses, despite the fact that grass lignocelluloses have a great potential for feedstocks of biofuel production and various biorefinery applications. Here, we report that manipulation of a gene encoding coniferaldehyde 5-hydroxylase (CAld5H, or ferulate 5-hydroxylase, F5H) leads to substantial alterations in syringyl (S)/guaiacyl (G) lignin aromatic composition in rice (Oryza sativa), a major model grass and commercially important crop. Among three CAld5H genes identified in rice, OsCAld5H1 (CYP84A5) appeared to be predominantly expressed in lignin-producing rice vegetative tissues. Down-regulation of OsCAld5H1 produced altered lignins largely enriched in G units, whereas up-regulation of OsCAld5H1 resulted in lignins enriched in S units, as revealed by a series of wet-chemical and NMR structural analyses. Our data collectively demonstrate that OsCAld5H1 expression is a major factor controlling S/G lignin composition in rice cell walls. Given that S/G lignin composition affects various biomass properties, we contemplate that manipulation of CAld5H gene expression represents a promising strategy to upgrade grass biomass for biorefinery applications.