Efficient hydrolysis of lignocellulose is the biggest technical challenges on forest bioenergy development due to lignin hindrance to bioconversion from lignocellulose to ethanol in poplar. Experiments were conducted to genetically modify poplar to decrease lignin content in order to enhance fermentable sugars which can be converted to ethanol. c3hl gene in Populus tomentosa was cloned and its RNAi vector expressing ds-RNA was constructed. 8 transgenic lines harboring the RNAi constructs were obtained via the leaf-disc method and propagated by cutting for each lines in the greenhouse. The transcription level of c3hl in RNAi inhibition transgenic lines analyzed by real-time PCR decreased 89.04%, 82.22% and 68.38% in the RNAi inhibition line 323,32S and 322 compared with the control. Stem cross-section staining and microstructure observations showed that the xylem development and lignin deposition pattern in transgenic plant changed. Transgenic plants with lowest lignin content generally matched with the highest content of cellulose and soluble total sugars and the highest sacchri?cation ef?dency. The results indicated that lignin is probably the major factor in recalcitrance of cell walls to sacchari? cation. Moreover, it demonstrated that genetic reduction of lignin content effectively overcame cell wall recalcitrance to bioconversion.%利用克隆得到的毛白杨c3h1基因构建其RNAi抑制表达载体,通过根癌农杆菌介导的叶盘法转化银腺杨无性系84K,RealtimePCR检测表明其转基因株系323、325和322中c3h1基因表达量较野生型植株分别下调89.04％、82.22％和68.38％；茎横切片组化染色和显微结构观察表明转基因植株木质部发育和木质素沉积方式发生了改变；木质素、纤维素含量测定及苯酚—硫酸法总糖含量与HPLC法可溶性总糖和单糖含量检测结果表明:转基因植株木质素含量平均降低23.00％,最高可达39.71％;酸前处理效率最高提高了41.39％;未经酸处理直接酶解的糖化效率是对照植株的2.34～2.72倍,322株系和323株系比对照植株经酸前处理后再酶解的糖化效率高出81.18％和375.53％.
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