Ethanol production from lignocellulosic biomass has been considered an alternative to corn-based ethanol and fossil fuel. However, the secondary cell wall structure prevents efficient degradation of cellulose. Expression of cell wall degrading enzymes has been suggested as one solution to generate suitable feedstocks for lignocellulosic ethanol production. Swollenin (SWO), originating from Trichoderma reesei, disrupts cellulose structure with low-level hydrolytic activity to the glucan chain. Previously, characterization of T. reesei SWO has been carried out in multiple microorganisms and tobacco. This study heterologously overexpressed T. reesei SWO in hybrid poplar (Populus tremula × alba), a promising feedstock for biofuel production, under the control of either the constitutive Cauliflower Mosaic Virus 35S (CaMV 35S) promoter or the putative vascular tissue specific Subterranean Clover Stunt Virus S7 (SCSV) promoter. Transgenic poplar lines with high or moderate SWO expression level showed abnormal growth and reduced biomass production, along with increased glucose and reduced lignin contents. Increased cellulose crystallinity was observed in two transgenic events. This study also investigated the effect of in planta SWO expression on cellulose saccharification efficiency and found that transgenic events improved glucan conversion rates compared to wild type poplar. The results suggest SWO-overexpressing transgenic poplar lines could be a potential feedstock for ethanol production.

从木质纤维素生物质生产乙醇被认为是玉米基乙醇和化石燃料的替代品。然而，二次细胞壁结构阻止了纤维素的有效降解。已经提出了细胞壁降解酶的表达作为一种产生合适的原料以生产木质纤维素乙醇的溶液。源自里氏木霉的Swollenin（SWO）破坏了纤维素结构，并具有低水平的葡聚糖链水解活性。以前，里氏木霉SWO的表征已在多种微生物和烟草中进行。这项研究异源过表达里氏木霉SWO在杂种杨（杨杨 × 白杨）），一种有前途的生物燃料生产原料，可以在花椰菜花叶病毒35S（CaMV 35S）启动子或假定的维管组织特有的地下三叶草特技病毒S7（SCSV）启动子的控制下运行。具有高或中等SWO表达水平的转基因杨树品系显示异常生长和生物量产生减少，以及葡萄糖增加和木质素含量减少。在两个转基因事件中观察到纤维素结晶度增加。这项研究还研究了植物中SWO表达对纤维素糖化效率的影响，并发现与野生型杨树相比，转基因事件提高了葡聚糖的转化率。结果表明SWO-过表达的转基因杨树品系可能是乙醇生产的潜在原料。