BioDiscovery Institute and Department of Biological Sciences, BioDiscovery Institute, University of North Texas, Denton, TX, 76201, USA.
BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, 37830, USA.
New Phytol. 2018 Sep;219(4):1235-1251. doi: 10.1111/nph.15258. Epub 2018 Jun 27.
A reduction in the lignin content in transgenic plants induces the ectopic expression of defense genes, but the importance of altered lignin composition in such phenomena remains unclear. Two Arabidopsis lines with similar lignin contents, but strikingly different lignin compositions, exhibited different quantitative and qualitative transcriptional responses. Plants with lignin composed primarily of guaiacyl units overexpressed genes responsive to oomycete and bacterial pathogen attack, whereas plants with lignin composed primarily of syringyl units expressed a far greater number of defense genes, including some associated with cis-jasmone-mediated responses to aphids; these plants exhibited altered responsiveness to bacterial and aphid inoculation. Several of the defense genes were differentially induced by water-soluble extracts from cell walls of plants of the two lines. Glycome profiling, fractionation and enzymatic digestion studies indicated that the different lignin compositions led to differential extractability of a range of heterogeneous oligosaccharide epitopes, with elicitor activity originating from different cell wall polymers. Alteration of lignin composition affects interactions with plant cell wall matrix polysaccharides to alter the sequestration of multiple latent defense signal molecules with an impact on biotic stress responses.
转基因植物中木质素含量的降低会诱导防御基因的异位表达，但改变木质素组成在这种现象中的重要性仍不清楚。两种木质素含量相似但木质素组成明显不同的拟南芥品系表现出不同的定量和定性转录响应。主要由愈创木基单元组成木质素的植物过表达对卵菌和细菌病原体攻击有反应的基因，而主要由丁香基单元组成木质素的植物表达了更多的防御基因，包括一些与茉莉酸介导的对蚜虫的反应有关的基因；这些植物对细菌和蚜虫接种的反应发生了改变。两种品系植物细胞壁的水溶性提取物可诱导几种防御基因的差异表达。糖组分析、分级和酶消化研究表明，不同的木质素组成导致一系列异质寡糖表位的提取能力不同，具有激发活性的来源于不同的细胞壁聚合物。木质素组成的改变会影响与植物细胞壁基质多糖的相互作用，从而改变多种潜在防御信号分子的隔离，从而影响生物胁迫反应。
