ELUCIDATION OF LIGNIFICATION MECHANISM OF WOODY PLANTS BY GENETIC ENGINEERING

为了从分子生物学角度阐明木本植物木质化的机理，从杂种白杨（Populus kitakamiensis）中分离了苯丙氨酸解氨酶（PAL）、肉桂酸4-羟化酶（CA 4 H）、O-甲基转移酶（OMT）和过氧化物酶（PO）基因。其中PAL（palg 2b）、CH 4 H（cyp 73 a）、OMT（homt 1）和PO（prxA 3a、prxA 4a）基因通过Northern杂交和组织切片表达观察，鉴定为与木质化有关的基因，并利用反义RNA技术构建了烟草和白杨木质素合成调控基因转化子。与普通烟草和白杨相比，OMT转化子的OMT活性和木质素含量都较低，并具有木质素特有的化学结构，即缩合单元含量较低，愈创木基单元和可降解的化学结构较多。

To elucidate the lignification mechanism of woody plants from a viewpoint of molecular biology, some genes encoding phenylalanine ammonia-ly ase (PAL), cinnamate 4-hydroxylase (CA4H), O-methyltransferase (OMT) and peroxidase (PO) were isolated from the hybrid aspen (Populus kitakamiensis). Of these genes, PAL (palg2b), CH4H (cyp73a), OMT (homt1), and PO (prxA3a, prxA4a) were identified as the genes involved in lignification by the northem hybridization and the expression observation on tissue slices with reporter gene (GUS gene).These transformants of tobacco and poplar controlling the lignin biosynthesis by antisense RNA method with those identified genes were formed. The transformants concerning OMT have lower OMT activity and lignin content than those of normal tobacco and poplar, and have a characteristic lignin chemical structure consisting of lower amount of condensed units, and more of guaiacyl unit and degradable chemical structures.