GA20ox基因过表达木材品质性状及其转基因纳米纤维素改良纸浆性能研究

Overexpression of Gibberellin 20-Oxidase Gene(GA20ox)in the Xylem of Poplar to Improve Wood Properties,and Paper Qualities Modified by GM-Nanocellulose

赤霉素通过促进细胞分裂调控树木生长发育,但有关赤霉素对于木材品质性状影响的研究报道较少。利用木质部特异表达的糖基转移酶8D1(GT8D1)启动子驱动GA20ox基因的表达,可以改良木材品质性状和纸张性能。实验构建GT8D1启动子驱动GA20ox基因在杨树中过表达获得转基因杨树,并在温室中扦插后得到转基因株系供试。取两年生转基因植株,分析木质素、纤维素等组分含量及其木材结构变化。结果表明,在GT8D1启动子驱动下,GA20ox基因的过表达加速了杨树转基因植株赤霉素的合成,刺激了形成层细胞分裂和树木的生长,有利于转基因植株的木材物质积累。转基因株系的木质素中紫丁香基单体(S)与愈创木基单体(G)的比值显著提高。通过TEMPO氧化法制备纳米纤维素,发现转基因杨树样本的纳米纤维素直径显著增加。以漂白松木浆为基础,分别添加5%浓度的转基因和非转基因材料制备的纳米纤维素进行纸张性能测试。分析显示,与对照组相比,转基因纳米纤维素(GM-nanocellulose)纸样纸张抗拉强度和耐破强度提升显著增多。研究结论为利用现代遗传工程技术改良制浆造纸原料物理性质和化学组分,优化制浆造纸新工艺,发展绿色、低碳和环保的新轻工业态开拓了新思路、提供了新途径。

Gibberellins(GAs)regulates plant growth and development by promoting cell division,but there are few reports on the fact that how the synthesis pathway of gibberellin affects wood formation and wood properties.In this paper,we reported new progress in improving wood quality and paper properties by xylem specific expression of glycosyltransferase promoter(8D1),driving and regulating the expression of GA20-oxidase(GA20ox)gene in poplar.The overexpression of GA20ox gene driven by 8D1 promoter was conducted in poplar;transgenic materials was obtained;and the transgenic lines were propagated by cuttings and planted in greenhouse for testing.The content of lignin,cellulose and other components and the wood structure variation were analyzed by the two years old clonal samples.The results showed that the overexpression of GA20ox gene,driven by 8D1 promoter,accelerated the synthesis of gibberellin in transgenic poplar plants,and stimulated cambium cell division and xylem differentiation and development,which was conducive to wood accumulation in transgenic plants.The analysis of lignin structure showed that the ratio of lilac monomer(S)to coniferol monomer(G)in lignin of transgenic strains was significantly increased.Nanocellulose was prepared by TEMPO oxidation method,and the diameter of nanocellulose in transgenic wood samples increased significantly.On the basis of bleached pine pulp,nanocellulose prepared with 5%concentration of GM and non-GM materials were added,and the paper properties were tested.In the pulp and papermaking processing,the paper tensile strength and burst resistance index can be significantly improved by adding transgenic poplar nanocellulose.We prospect that this results may suggest some new ideas and provide a new way to improve the physical properties and chemical components of pulp and paper raw materials;and optimize the new processing technology of pulp and paper;and the aims of green,lowcarbon and environmental-friendly for the new light industry could be realized.