College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, PR China.
College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, PR China; Department of Chemical Engineering, Hua Qiao University, Xiamen, 361021, Fujian, PR China.
Plant Physiol Biochem. 2019 Jun;139:672-680. doi: 10.1016/j.plaphy.2019.03.035. Epub 2019 Apr 23.
Cell wall components and structure impact the physical and mechanical properties of plants, thereby affecting wood applications. Lignin is the most abundant biopolymer after cellulose in the wood cell wall and can be modified by certain lignin biosynthesis enzymes. 4-Coumarate: coenzyme A ligase(4CL) is an important lignin biosynthesis enzyme. To demonstrate the impact of the regulation of Pto4CL1 from poplar on wood properties, we analyzed the composition and anatomy of 5-year-old Pto4CL1-modified poplar cell walls, assessing the density, strength, volume shrinkage, and impact toughness of the transgenic trees. These results showed that the up-regulation of Pto4CL1 increased the lignin content to 46.65% from 33.11% in the control plants, while hydrophilic polysaccharides such as cellulose, hemi-cellulose, and pectin decreased. In contrast, the down-regulation of Pto4CL1 resulted in a reduction in lignin content to 27.39%, and the content of cellulose and hemi-cellulose showed compensatory variation. Raman spectroscopy showed that the change in lignin in the transgenic events was embodied in the deposition and concentration of lignin in the secondary cell wall. Moreover, the increased lignin content caused significantly increased wood strength and slightly increased wood density. In contrast, a reduction in lignin content resulted in a significant decrease in wood strength and a slight decrease in wood density. However, the Pto4CL1-modified trees had similar stiffness to the control group. We also found a significant decrease in volume shrinkage and increase in impact toughness in the low-lignin events. These results indicate that Pto4CL1 regulation alters the chemical composition of plant cell walls and these changes affect the physical and mechanical properties of the wood.
细胞壁成分和结构影响植物的物理和机械性能，从而影响木材的应用。木质素是木材细胞壁中仅次于纤维素的最丰富的生物聚合物，可通过某些木质素生物合成酶进行修饰。4-香豆酸：辅酶 A 连接酶（4CL）是木质素生物合成的重要酶。为了证明调控杨树 4CL1 对木材性质的影响，我们分析了 5 年生 4CL1 修饰杨树细胞壁的组成和解剖结构，评估了转基因树木的密度、强度、体积收缩和冲击韧性。结果表明，4CL1 的上调使木质素含量从对照植物的 33.11%增加到 46.65%，而纤维素、半纤维素和果胶等亲水性多糖则减少。相比之下，4CL1 的下调导致木质素含量降低到 27.39%，纤维素和半纤维素的含量表现出补偿性变化。拉曼光谱表明，转基因事件中木质素的变化体现在次生细胞壁中木质素的沉积和浓度上。此外，木质素含量的增加导致木材强度显著增加，木材密度略有增加。相反，木质素含量的降低导致木材强度显著降低，木材密度略有降低。然而，4CL1 修饰的树木与对照组的刚度相似。我们还发现低木质素事件的体积收缩显著减少，冲击韧性显著增加。这些结果表明，4CL1 的调控改变了植物细胞壁的化学成分，这些变化影响了木材的物理和机械性能。
