Increasing the wood density to a preferred range contributes to upgrading the value of wood as raw material. Lignin manipulation can also improve wood quality. This study attempted to accelerate secondary cell wall formation in transgenic poplar with an altered lignin structure. To achieve this, OsSWN1, a rice master switch for secondary cell wall formation in fiber cells, was overexpressed in poplar plants in which monolignol biosynthesis was suppressed by the expression of an RNA-interference construct targeted to the gene for cinnamyl alcohol dehydrogenase 1. The generated transgenic poplars successfully overexpressed the chimeric OsSWN1 construct and monolignol biosynthesis remained altered in these plants. Secondary cell wall thickness was increased in the transgenic plants and their wood density was higher compared to the background line. No difference in lignin content was observed, except in one transgenic line. High saccharification characteristics observed in the background line were preserved in the transgenic line with lower OsSWN1 overexpression, but higher OsSWN1 overexpression had a slight negative impact on enzyme saccharification. Our data suggested that fine-tuning of accelerated deposition of the secondary cell wall combined with alteration of monolignol biosynthesis should improve the lignocellulose quality for conventional and future biorefinery uses.

中文翻译：

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转基因杨树中木质素结构和次生细胞壁形成的同时操纵

将木材密度增加到优选范围有助于提高木材作为原材料的价值。木质素处理还可以改善木材质量。这项研究试图加快木质素结构改变的转基因杨树中次生细胞壁的形成。为了实现这一目标，OsSWN1（一种用于在纤维细胞中形成次级细胞壁的水稻主开关）在杨树植物中过表达，其中通过针对肉桂醇脱氢酶1基因的RNA干扰构建体的表达抑制了单木酚醇的生物合成。产生的转基因杨树成功地过表达了嵌合的OsSWN1构建体，并且这些植物中的单木酚醇生物合成仍然发生了变化。与背景品系相比，转基因植物中次生细胞壁的厚度增加，其木材密度更高。除了在一个转基因品系中，未观察到木质素含量的差异。在背景品系中观察到的高糖化特性保留在具有较低OsSWN1过表达的转基因品系中，但是较高的OsSWN1过表达对酶糖化有轻微的负面影响。我们的数据表明，对二级细胞壁加速沉积的微调与单木酚生物合成的改变相结合，可以改善常规和未来生物炼制用途中木质纤维素的质量。