Unda Faride, de Vries Lisanne, Karlen Steven D, Rainbow Jordan, Zhang Chengcheng, Bartley Laura E, Kim Hoon, Ralph John, Mansfield Shawn D
Department of Wood Science, Faculty of Forestry, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
US Department of Energy (DOE) Great Lakes Bioenergy Research Center, The Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, 53726, USA.
Biotechnol Biofuels Bioprod. 2024 Jul 13;17(1):97. doi: 10.1186/s13068-024-02544-y.
The phenolic polymer lignin is one of the primary chemical constituents of the plant secondary cell wall. Due to the inherent plasticity of lignin biosynthesis, several phenolic monomers have been shown to be incorporated into the polymer, as long as the monomer can undergo radicalization so it can participate in coupling reactions. In this study, we significantly enhance the level of incorporation of monolignol ferulate conjugates into the lignin polymer to improve the digestibility of lignocellulosic biomass.
Overexpression of a rice Feruloyl-CoA Monolignol Transferase (FMT), OsFMT1, in hybrid poplar (Populus alba x grandidentata) produced transgenic trees clearly displaying increased cell wall-bound ester-linked ferulate, p-hydroxybenzoate, and p-coumarate, all of which are in the lignin cell wall fraction, as shown by NMR and DFRC. We also demonstrate the use of a novel UV-Vis spectroscopic technique to rapidly screen plants for the presence of both ferulate and p-hydroxybenzoate esters. Lastly we show, via saccharification assays, that the OsFMT1 transgenic p oplars have significantly improved processing efficiency compared to wild-type and Angelica sinensis-FMT-expressing poplars.
The findings demonstrate that OsFMT1 has a broad substrate specificity and a higher catalytic efficiency compared to the previously published FMT from Angelica sinensis (AsFMT). Importantly, enhanced wood processability makes OsFMT1 a promising gene to optimize the composition of lignocellulosic biomass.
酚类聚合物木质素是植物次生细胞壁的主要化学成分之一。由于木质素生物合成具有内在可塑性，已证明只要单体能够发生自由基化从而参与偶联反应，几种酚类单体就可以掺入该聚合物中。在本研究中，我们显著提高了单木质醇阿魏酸共轭物掺入木质素聚合物中的水平，以提高木质纤维素生物质的消化率。
在杂种杨树（银白杨×大齿杨）中过表达水稻阿魏酰辅酶A单木质醇转移酶（FMT）OsFMT1，产生的转基因树明显显示出细胞壁结合的酯连接阿魏酸、对羟基苯甲酸和对香豆酸增加，如核磁共振（NMR）和二氟代试剂衍生化还原裂解（DFRC）所示，所有这些都存在于木质素细胞壁组分中。我们还展示了一种新型紫外可见光谱技术的应用，该技术可快速筛选植物中阿魏酸酯和对羟基苯甲酸酯的存在情况。最后，通过糖化分析表明，与野生型杨树和表达当归FMT的杨树相比，OsFMT1转基因杨树的加工效率显著提高。
研究结果表明，与先前发表的来自当归的FMT（AsFMT）相比，OsFMT1具有广泛的底物特异性和更高的催化效率。重要的是，提高木材加工性能使OsFMT1成为优化木质纤维素生物质组成的一个有前景的基因。
