摘要：
随着我国木材产量难以满足日益增长的木材需求,人工林在缓解国内木材市场供需矛盾上发挥着越来越重要的作用.我国人工林面积居世界首位,但木材性质较差,限制了其应用范围,培育性质优良的人工林木材具有重要意义.利用基因工程技术可以从源头有效提高人工林木材的性质,进而提高木材质量,在有限林地上实现资源的高效利用.本文综述基因工程技术对人工林木材化学、构造及其物理力学性质的影响,以期为人工林木材性质基因工程改良的研究和应用提供参考.基因工程改良对木材化学组成的影响主要体现在木质素含量和木质素单体比例、纤维素和半纤维素及其他化学成分的变化上,选择不同的目的基因将对木材化学组成产生不同的影响,其中利用基因工程降低木材木质素含量的研究最为活跃.基因工程改良对木材构造的影响主要体现在细胞形态和微纤丝取向的变化上,现有研究表明通过基因工程改良能有效提高人工林木材纤维质量,进而提高纸浆质量,而且基因工程改良还会对木材微纤丝角产生影响;木材细胞形态和微纤丝角的改变会引起材性的变化,为通过基因定向改变木材细胞形态或微纤丝角,进而达到人工林木材材性改良的目的提供了思路.基因工程改良对木材的物理力学性质也具有显著影响,已有研究发现多种目的基因可对木材密度、干缩湿胀率和木材强度等产生影响.目前,有关人工林木材性质基因工程改良的研究仍处于初级阶段,尚有一些问题需要进一步解决,建议今后的研究重点可从以下3方面展开:1)转基因植株细胞壁的物质形成受到精细的时空调节,因此应考虑时间和环境因素对基因工程改良木材所造成的影响,深入研究基因工程改良木材优良性质的稳定性,探索有利于基因稳定表达的培育环境和措施;2)虽然基因工程改良会对木材化学、构造及其物理力学性质等造成影响,但是木材性质经同一种基因改良后变化程度有差异,因此有必要寻找能稳定遗传的基因并提高基因表达水平的方法;3)基因工程改良木材基础性质的研究还远远不足,需要重点研究基因工程改良人工林木材化学组成、构造及其物理力学性质等方面的变化,寻找能稳定改善木材性质的基因,建立一个完整可靠的基础数据库.%Nowadays,it is difficult for the naturally-growing wood to meet the growing demand in China.Thus,plantation wood plays a more and more important role in alleviating the contradiction between supply and demand.Plantation area in China ranks first in the world,but the quality of wood is poor,which limits its application.Therefore,it is becoming more and more important to cultivate good quality plantation wood.Genetic engineering can from the fountainhead improve the quality of the plantation wood in the limited forestland.In order to provide reference for further research and application of genetic engineering to the quality of plantation wood,this paper reviewed the effects of genetic engineering on wood chemistry,structure and physical & mechanical properties of plantation wood.For wood chemistry,the effects of genetic engineering are mainly on the changes in lignin content,proportion of lignin monomer,and the contents of cellulose,hemicellulose and other chemical compositions.The research on reducing lignin content achieved the most rapid development.For wood structure,the effects are mainly on the changes of cell morphology and microfibril orientation,and therefore the improvement of the quality of fibers,and the quality of pulp is expected.For wood physical and mechanical properties,the effects on density,shrinkage,and strength with many target genes of obvious impacts are reported.At present,genetic engineering improvement of plantation wood quality is still in the primary stage and there are still some problems to be solved.1) The cell wall formation of transgenic plants is under precise regulation of time and space.Therefore,the impacts of time and environmental factors on the transgenic plants,the stability of genetic engineering improving wood quality,and the cultivation environment and measures that conducive to the stable expression of target genes should be deeply studied.2) Genetic engineering can improve wood properties,but the degree of improvement differs.Thus,it is necessary to find the genes that can be stably inherited and the methods to improve the expression level of target genes.3) The fundamental research on the genetic improvement of wood properties is far from sufficiency.The variation of the improvements needs to be further studied,more target genes that can make stable improvement need to be found and a complete and reliable basic database needs to be established.
