Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA.
Plant J. 2010 Dec;64(6):898-911. doi: 10.1111/j.1365-313X.2010.04391.x. Epub 2010 Nov 4.
The presence of the phenylpropanoid polymer lignin in plant cell walls impedes breakdown of polysaccharides to the fermentable sugars that are used in biofuel production. Genetically modified plants with altered lignin properties hold great promise to improve biomass degradability. Here, we describe the generation of a new type of lignin enriched in 5-hydroxy-guaiacyl units by over-expressing ferulate 5-hydroxylase in a line of Arabidopsis lacking caffeic acid O-methyltransferase. The lignin modification strategy had a profound impact on plant growth and development and cell-wall properties, and resulted in male sterility due to complete disruption of formation of the pollen wall. The modified plants showed significantly improved cell-wall enzymatic saccharification efficiency without a reduction in post-harvest biomass yield despite the alterations in the overall growth morphology. This study demonstrated the plasticity of lignin polymerization in terms of incorporation of unusual monomers that chemically resemble conventional monomers, and also revealed the link between the biosynthetic pathways of lignin and the pollen wall-forming sporopollenin.
植物细胞壁中苯基丙烷聚合物木质素的存在阻碍了多糖分解为生物燃料生产中使用的可发酵糖。具有改变木质素特性的转基因植物具有很大的潜力来提高生物质的可降解性。在这里，我们描述了通过在缺乏咖啡酸-O-甲基转移酶的拟南芥系中过表达阿魏酸 5-羟化酶，产生一种富含 5-羟基愈创木基单元的新型木质素。木质素修饰策略对植物的生长发育和细胞壁特性产生了深远的影响，并由于花粉壁完全破坏而导致雄性不育。尽管整体生长形态发生了变化，但经过修饰的植物表现出显著提高的细胞壁酶解效率，而不会降低收获后的生物量产量。这项研究证明了木质素聚合在纳入化学上类似于常规单体的不寻常单体方面的可塑性，还揭示了木质素生物合成途径与花粉壁形成的孢粉素之间的联系。
