ELUCIDATION OF LIGNIFICATION MECHANISM OF WOODY PLANTS BY GENETIC ENGINEERING

为了从分子生物学的角度阐明木本植物的木质化机理，从杂交杨中分离了苯丙氨酸氨基转移酶(PAL)、肉桂酸4-羟基酶(CA4H)、O-甲基转移酶(OMT)和过氧化物酶(PO)基因。其中PAL(Palg2b)、CH4H(Cyp73a)、OMT(Homt1)和PO(prxA3a、prxA4a)与报告基因(GUS基因)杂交和组织切片表达观察，确定与木质素合成有关的基因为PAL(Palg2b)、CH4H(Cyp73a)、OMT(Homt1)和PO(PrxA4a)。与普通烟草和杨树相比，与OMT相关的转化子具有较低的OMT活性和木质素含量，并且具有木素化学结构特征，即缩合单元数量较少，愈创木基单元和可降解化学结构较多。

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.