Lignification in the flax stem:: evidence for an unusual lignin in bast fibers
Lignification in the flax stem:: evidence for an unusual lignin in bast fibers
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DOI：
10.1007/s00425-005-1537-1
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发表时间：
2005-10-01
期刊：
影响因子：
4.3
通讯作者：
Chabbert, B
中科院分区：
文献类型：
--
作者：
Day, A;Ruel, K;Chabbert, B
在我们对亚麻（Linum usitatissimum L）韧皮纤维细胞壁形成和成熟的研究背景下，我们（1）证实了韧皮纤维中木质素的存在，并且（2）在两个发育阶段对这种木质素的化学性质进行了定量和表征。组织化学方法（Weisner试剂、Maule试剂和KMnO₄染色）在光学显微镜和电子显微镜水平上表明韧皮纤维中存在木质素，这通过化学分析（乙酰溴）得到了证实。一般来说，亚麻韧皮纤维中的木质素含量在干细胞壁残渣（CWRs）的1.5%到4.2%之间变化，而亚麻木质部组织中的木质素含量在23.7%到31.4%之间变化。免疫学和化学分析（硫代酸解法和硝基苯氧化）表明，亚麻木质部和韧皮纤维的木质素都富含愈创木基（G）单元，S/G值小于0.5。在韧皮纤维中，高灵敏度的免疫学探针能够检测到胞间层、细胞壁连接处以及次生壁S1层中的缩合愈创木基型（G）木质素。此外，在整个次生细胞壁中还能检测到少量的混合愈创木基 - 紫丁香基（GS）木质素。化学分析表明，亚麻韧皮纤维木质素比相应的木质部木质素更缩合。此外，H单元在从韧皮纤维木质素释放的单体中占比高达25%，而相应的木质部组织中该比例为1%。这样的观察结果表明，亚麻韧皮纤维木质素的结构与更典型的“木本植物木质素”有显著差异，因此表明亚麻韧皮纤维是研究一种不寻常的木质化过程的一个有趣的体系。
In the context of our research on cell wall formation and maturation in flax (Linum usitatissimum L) bast fibers, we (1) confirmed the presence of lignin in bast fibers and (2) quantified and characterized the chemical nature of this lignin at two developmental stages. Histochemical methods (Weisner and Maule reagents and KMnO4-staining) indicating the presence of lignin in bast fibers at the light and electron microscope levels were confirmed by chemical analyses (acetyl bromide). In general, the lignin content in flax bast fibers varied between 1.5% and 4.2% of the dry cell wall residues (CWRs) as compared to values varying between 23.7% and 31.4% in flax xylem tissues. Immunological and chemical analyses (thioacidolysis and nitrobenzene oxidation) indicated that both flax xylem- and bast fiber-lignins were rich in guaiacyl (G) units with S/G values inferior to 0.5. In bast fibers, the highly sensitive immunological probes allowed the detection of condensed guaiacyl-type (G) lignins in the middle lamella, cell wall junctions, and in the S1 layer of the secondary wall. In addition, lower quantities of mixed guaiacyl-syringyl (GS) lignins could be detected throughout the secondary cell wall. Chemical analyses suggested that flax bast-fiber lignin is more condensed than the corresponding xylem lignin. In addition, H units represented up to 25% of the monomers released from bast-fiber lignin as opposed to a value of 1% for the corresponding xylem tissue. Such an observation indicates that the structure of flax bast-fiber lignin is significantly different from that of the more typical 'woody plant lignin', thereby suggesting that flax bast fibers represent an interesting system for studying an unusual lignification process.