Chen B W, Xiao Y F, Li J J, Liu H L, Qin Z H, Gai Y, Jiang X N
School of Biology Science and Biotechnology, Beijing Forestry University, Beijing, China
Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, Nanning, China
Genet Mol Res. 2016 Dec 2;15(4):gmr-15-04-gmr.15049062. doi: 10.4238/gmr15049062.
Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in lignin biosynthesis. The genus Eucalyptus belongs to the family Myrtaceae, which is the main cultivated species in China. Eucalyptus urophylla GLU4 (GLU4) is widely grown in Guangxi. It is preferred for pulping because of its excellent cellulose content and fiber length. Based on GLU4 and CAD gene expression, a Eucalyptus variety low in lignin content should be obtained using transgenic technology, which could reduce the cost of pulp and improve the pulping rate, and have favorable prospects for application. However, the role and function of CAD in GLU4 is still unclear. In the present study, EuCAD was cloned from GLU4 and identified using bioinformatic tools. Subsequently, in order to evaluate its impact on lignin synthesis, a full-length EuCAD RNAi vector was constructed, and transgenic tobacco was obtained via Agrobacterium-mediated transformation. A significant decrease in CAD expression and lignin content in transgenic tobacco demonstrated a key role for EuCAD in lignin biosynthesis and established a regulatory role for RNAi. In our study, the direct molecular basis of EuCAD expression was determined, and the potential regulatory effects of this RNAi vector on lignin biosynthesis in E. urophylla GLU4 were demonstrated. Our results provide a theoretical basis for the study of lignin biosynthesis in Eucalyptus.
肉桂醇脱氢酶（CAD）催化木质素生物合成的最后一步。桉属植物属于桃金娘科，是中国主要的栽培树种。尾叶桉GLU4（GLU4）在广西广泛种植。由于其优异的纤维素含量和纤维长度，它是制浆的优选材料。基于GLU4和CAD基因表达，应利用转基因技术获得木质素含量低的桉树品种，这可以降低制浆成本并提高制浆率，具有良好的应用前景。然而，CAD在GLU4中的作用和功能仍不清楚。在本研究中，从GLU4中克隆了EuCAD并使用生物信息学工具进行了鉴定。随后，为了评估其对木质素合成的影响，构建了全长EuCAD RNAi载体，并通过农杆菌介导的转化获得了转基因烟草。转基因烟草中CAD表达和木质素含量的显著降低证明了EuCAD在木质素生物合成中的关键作用，并确立了RNAi的调控作用。在我们的研究中，确定了EuCAD表达的直接分子基础，并证明了该RNAi载体对尾叶桉GLU4中木质素生物合成的潜在调控作用。我们的结果为桉树木质素生物合成的研究提供了理论依据。
