Abstract

Here, the regulatory effects of co-transforming catechol-O-methyltransferase (COMT) and ca-ffeoyl‑CoA O-methyltransferase (CCoAOMT) isolated from Eucalyptus urophylla S. T. Blake on the biosynthesis of lignin monomers were investigated using a tobacco as a model system. Tobacco (Nicotiana tabacum L.) plants were separately transformed with sense EuCOMT and full-length interfering RNA of EuCCoAOMT, and co-transformed with both EuCOMT and EuCCoAOMT respectively. The target genes’ expression levels, the lignin, lignin monomer and cellulose contents, and the anatomical structures of the stems in transgenic tobacco lines were determined. The expression of EuCOMT was detected, and a significant inhibition of tobacco’s native CCoAOMT expression was triggered by the full-length interfering RNA of EuCCoAOMT in transgenic tobacco plants. No significant differences were observed in stem diameter at both the 5th and 7th nodes among transgenic and wild type plants, nor in the xylem cell area or cell wall thickness at the 7th node of the stem. Compared with wild-type plants, the changes in the lignin and cellulose contents in transgenic plants were less than 10%. The G-lignin content of the co-transformed transgenic plants decreased by 57.38%, resulting in a 114.94% increase in the S/G ratio. Thus, the suppression of CCoAOMT’s expression substantially inhibited the synthesis of G-lignin, and the optimal directional regulatory effect on the S/G ratio was observed in plants co-regulated by EuCOMT and EuCCoAOMT.

中文翻译：

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共转化尾叶桉木邻苯二酚-O-甲基转移酶和咖啡酰-CoA O-甲基转移酶对转基因烟草木质素单体生物合成的影响

摘要

在这里，以烟草为模型系统，研究了从尾叶桉（Eucalyptus urophylla ST Blake ）分离的共转化儿茶酚-O-甲基转移酶（COMT）和咖啡酰-CoA O-甲基转移酶（CCoAOMT）对木质素单体生物合成的调控作用。。烟草（烟草属）植物分别用感转化EuCOMT的和全长干扰RNA EuCCoAOMT，并与二者共转化EuCOMT和EuCCoAOMT分别。确定了目标基因的表达水平，木质素，木质素单体和纤维素含量，以及转基因烟草品系中茎的解剖结构。检测到EuCOMT的表达，并且通过EuCCoAOMT的全长干扰RNA触发了烟草天然CCoAOMT表达的显着抑制在转基因烟草植物中。在转基因植物和野生型植物之间，在第5和第7节的茎直径没有发现显着差异，在茎的第7节的木质部细胞面积或细胞壁厚度也没有观察到显着差异。与野生型植物相比，转基因植物中木质素和纤维素含量的变化小于10％。共转化的转基因植物的G-木质素含量降低了57.38％，导致S / G比提高了114.94％。因此，抑制CCoAOMT的表达实质上抑制了G-木质素的合成，并且在EuCOMT和EuCCoAOMT共同调控的植物中观察到了对S / G比的最佳方向调控作用。