Modified lignin in tobacco and poplar plants over-expressing the Arabidopsis gene encoding ferulate 5-hydroxylase
Modified lignin in tobacco and poplar plants over-expressing the Arabidopsis gene encoding ferulate 5-hydroxylase
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DOI：
10.1046/j.1365-313x.2000.00727.x
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发表时间：
2000-05-01
期刊：
影响因子：
7.2
通讯作者：
Chapple, C
中科院分区：
文献类型：
--
作者：
Franke, R;McMichael, CM;Chapple, C
阿魏酸5-羟化酶（F5 H）是一种细胞色素P450依赖性单加氧酶，其在导致芥子酸和异辛基木质素生物合成的途径中催化阿魏酸、松柏醛和松柏醇的羟基化。在拟南芥中的早期研究已经证明，F5 H过表达增加了木质素甘精酰单体含量，并消除了其沉积的组织特异性。为了确定这种酶是否在经历二次生长的植物中具有类似的调节作用，我们在烟草和白杨中过表达F5 H基因。在烟草中，在花椰菜花叶病毒35 S启动子控制下的F5 H的过表达增加了叶柄中木质素单烯丙基单体的含量，但对茎中的木质化没有可检测的影响。相比之下，当肉桂酸4-羟化酶（C4 H）启动子用于驱动F5 H的表达，有茎木质素异戊烯基单体含量的显着增加。巯基乙酸和Klason木质素在C4 H-F5 H系中的产量低于野生型，表明F5 H过表达导致转基因植物中木质素的沉积减少或可提取性改变。组织化学分析表明，C4 H-F5 H转基因株系中的新木质素的羟基肉桂醛含量发生了变化。携带C4 H-F5 H转基因的转基因白杨也显示出增强的木质素双辛基单体含量。总之，这些数据表明，愈创木基取代的木质素前体的羟基化控制木质素单体组成的木本植物，和F5 H过表达是一个可行的代谢工程策略，用于修改木质素生物合成的森林物种。
Ferulate 5-hydroxylase (F5H) is a cytochrome P450-dependent monooxygenase that catalyses the hydroxylation of ferulic acid, coniferaldehyde and coniferyl alcohol in the pathways leading to sinapic acid and syringyl lignin biosynthesis. Earlier studies in Arabidopsis have demonstrated that F5H overexpression increases lignin syringyl monomer content and abolishes the tissue-specificity of its deposition. To determine whether this enzyme has a similar regulatory role in plants that undergo secondary growth, we over-expressed the F5H gene in tobacco and poplar. In tobacco, over-expression of F5H under the control of the cauliflower mosaic virus 35S promoter increased lignin syringyl monomer content in petioles, but had no detectable effect on lignification in stems. By contrast, when the cinnamate 4-hydroxylase (C4H) promoter was used to drive F5H expression, there was a significant increase in stem lignin syringyl monomer content. Yields of thioglycolic acid and Klason lignin in C4H-F5H lines were lower than in the wild-type, suggesting that F5H over-expression leads to a reduced deposition or an altered extractability of lignin in the transgenic plants. Histochemical analysis suggested that the novel lignin in C4H-F5H transgenic lines was altered in its content of hydroxycinnamyl aldehydes. Transgenic poplar trees carrying the C4H-F5H transgene also displayed enhanced lignin syringyl monomer content. Taken together, these data show that hydroxylation of guaiacyl-substituted lignin precursors controls lignin monomer composition in woody plants, and that F5H over-expression is a viable metabolic engineering strategy for modifying lignin biosynthesis in forest species.