Department of Wood Science, Faculty of Forestry, The University of British Columbia, Vancouver, BC, Canada.
Plant Biotechnol J. 2010 Apr;8(3):294-307. doi: 10.1111/j.1467-7652.2009.00483.x. Epub 2010 Jan 8.
To understand better the intricacies of secondary cell wall biosynthesis in trees, we investigated changes in cellulose chemistry and ultrastructure manifested by the mis-regulation of the poplar membrane-bound beta-1,4-endoglucanase orthologous to KORRIGAN (AtKOR). We isolated the poplar KORRIGAN gene from hybrid poplar (Populus albaxgrandidentata; designated PaxgKOR) and created a self-complementary (hairpin) RNAi suppression construct using PCR products derived from the gene. Additionally, AtKOR was employed to generate transgenic poplar over-expressing KORRIGAN. It was found that down-regulation leads to moderate to severe defects in plant growth, an irregular xylem (irx) phenotype, and significantly impacts the ultrastructure of the cellulose synthesized. The RNAi-suppressed lines deposited significantly reduced quantities of a more highly crystalline cellulose, while the hemicellulose content and, more specifically, the xylose content increased. In addition, the amount of soluble sucrose in the leaves and xylem decreased. Conversely, the AtKOR transgenics did not significantly alter cell wall development or plant growth parameters, but it did impact the ultrastructure of the cellulose produced, generating trees with less crystalline cellulose and reduced xylose content.
为了更好地理解树木次生细胞壁生物合成的复杂性，我们研究了拟南芥膜结合β-1,4-内切葡聚糖酶同源物 KORRIGAN（AtKOR）失调导致的纤维素化学和超微结构变化。我们从杂种杨树（Populus albaxgrandidentata；命名为 PaxgKOR）中分离出杨树 KORRIGAN 基因，并使用从基因衍生的 PCR 产物创建了自我互补（发夹）RNAi 抑制构建体。此外，还利用 AtKOR 生成了过表达 KORRIGAN 的转基因杨树。研究发现，下调会导致植物生长出现中度到严重缺陷、木质部不规则（irx）表型，并显著影响合成纤维素的超微结构。RNAi 抑制株系沉积的纤维素结晶度明显降低，而半纤维素含量增加，特别是木糖含量增加。此外，叶片和木质部中可溶性蔗糖的含量也减少了。相反，AtKOR 转基因植物不会显著改变细胞壁发育或植物生长参数，但会影响产生的纤维素的超微结构，生成纤维素结晶度降低且木糖含量减少的树木。
