Molecular Cloning Of The Genes Involved In The Wood Formation Of Populus Tomentosa Carr. And Their Expression In Tobacco And Poplar

Wood is the most important natural and renewable source in the world and it is the major raw material for the production of pulp and paper. During the manufacture of high-quality paper, lignin is chemically separated from the cellulose microfibrils components of wood in the period of pulping and bleaching reaction. Lignin extraction and remove of carbohydrate degradation products will consume large quantities of chemicals and energy leading to a poor environmental image for the industry. Therefore, it is highly desirable to effectively manipulate the key gene involved in the wood formation and produce the genetically modified trees with lowered lignin and pentosan content, or modified lignin composition to make it easier extract, while maintaining normal growth and structural integrity, and the resistance of wood to insects and pathogens. For these reasons, molecular cloning and regulation of the major gene controlling wood formation with gene transfer technologies are of theoretical and practical importance to produce the forest tree for desirable industrial pulping feedstocks. In this research, several cDNA clones encoding metabolism enzymes involved in the wood formation were isolated from the cDNA prepared from cambial zone of Populus tomentosa by the RT-PCR method and their plant expression vectors with sense, antisense, RNAi and two or three linear linked sense gene construct types have been constructed. The genetic effects of changing the expression of theses genes on growth, stem chemical content and histological anatomy structure were studied via Agrobacterium–mediated transformation of leaf disks in transgenic tobacco and poplar. The major results and conclusions are described as follows.1. The enzyme Uridine 5'Diphosphate-Glucose Dehydrogenase (UGDH) catalyzes...