Marjamaa Kaisa, Kukkola Eija M, Fagerstedt Kurt V
Technical Research Center of Finland (VTT), PL 1000, 02044 VTT, Finland.
J Exp Bot. 2009;60(2):367-76. doi: 10.1093/jxb/ern278.
Lignification is a cell wall fortifying process which occurs in xylem tissue in a scheduled manner during tissue differentiation. In this review, enzymes and the genes responsible for lignin biosynthesis have been studied with an emphasis on lignin polymerizing class III secretable plant peroxidases. Our aim is to understand the cell and molecular biology of the polymerization of lignin especially in tracheids and vessels of woody species but much of the experimental evidence comes from herbaceous plants. Class III peroxidases pose many problems for empirical work as their encoding genes are variable, their substrate specificities are wide and the half-life of many of the isozymes is very long. However, there is some evidence for the role of specific peroxidases in lignin polymerization through antisense mutants in tobacco and poplar and from tissue and cell culture lines of Picea abies and Zinnia elegans. Peroxidase enzyme action has been shown by substrate specificity studies and, for example, RT-PCR results have pointed out that many peroxidases have tissue-specific expression patterns. Tissue-level location of gene expression of some peroxidases has been studied by in situ hybridization and their cellular localization with antibodies and using EGFP-fusion genes. From these, it can be concluded that, although many of the xylem class III peroxidases have the potential for functioning in the synthesis of the lignin polymer, the combined information of catalytic properties, expression, and localization can reveal differences in the significance of different peroxidases in the lignification process.
木质化是一种细胞壁强化过程，在组织分化期间按计划发生于木质部组织中。在本综述中，对负责木质素生物合成的酶和基因进行了研究，重点是木质素聚合的III类可分泌植物过氧化物酶。我们的目的是了解木质素聚合的细胞和分子生物学，特别是在木本植物的管胞和导管中，但许多实验证据来自草本植物。III类过氧化物酶给实证研究带来了许多问题，因为它们的编码基因多变，底物特异性广泛，并且许多同工酶的半衰期很长。然而，通过烟草和杨树中的反义突变体以及来自云杉和百日草的组织和细胞系，有一些证据表明特定过氧化物酶在木质素聚合中的作用。通过底物特异性研究已经证明了过氧化物酶的酶促作用，例如，RT-PCR结果指出许多过氧化物酶具有组织特异性表达模式。通过原位杂交研究了一些过氧化物酶基因表达的组织水平定位，并使用抗体和EGFP融合基因对其进行细胞定位。由此可以得出结论，尽管许多木质部III类过氧化物酶具有在木质素聚合物合成中发挥作用的潜力，但催化特性、表达和定位的综合信息可以揭示不同过氧化物酶在木质化过程中的重要性差异。
