2种木质素单体在紫花苜蓿茎中沉积的研究

The Study of Two Lignin Monomers Deposition in Alfalfa Stem

【目的】紫花苜蓿是优质的豆科牧草,木质素的存在影响其利用效率。从木质素单体角度出发,研究愈创木基木质素(guaiacyl lignin,简称G木质素)和紫丁香基木质素(syringyl lignin,简称S木质素)在紫花苜蓿茎中不同节间的沉积。【方法】运用组织化学染色方法,对紫花苜蓿茎中2种木质素单体进行单独染色,制作临时切片,在显微镜下观测、拍照。【结果】紫花苜蓿上部节间沉积较少的木质素,下部节间沉积较多的木质素,这种差异主要由木质化的次生木质部大量生成和髓木质化引起;2种木质素单体沉积存在差异,上部节间,髓射线有S木质素沉积,无G木质素沉积;下部节间则在髓薄壁细胞有S木质素沉积,无G木质素沉积。【结论】2种木质素单体主要沉积在苜蓿茎的初生韧皮部、初生木质部、次生木质部和髓等组织,且下部节间沉积较多的木质素。2种木质素单体在苜蓿茎的沉积存在差异,在髓射线和髓薄壁细胞均表现为S木质素的沉积范围高于G木质素。

[ Objective ] Alfalfa cannot be well utilized by livestock. o sativa L. ） is a high quality forage legume, while the lignin This project aims to study the guaiacyl lignin （G- lignin） and syringyl lignin （ S - lignin） deposition pattern in stem of alfalfa and compare their differences. [ Method ] In this study, 2 kinds of lignin in the stem of alfalfa were individually stained with the method of histochemical staining, and the temporary sections were made and observed under the microscope. [ Result ] The results showed that the bottom internode had the most lignin deposition, and the least lignin deposition at top internode. The main reason for this was that the ligninfied proportion of secondary xylem and pith parenchyma were increased. There were significant differences of lignin deposition between two Lignin Monomers, there were S - lignin deposition but no G -lignin deposition in pith ray at top internode of alfalfa, and the same phenomenon was also showed in pith at bottom internode of alfalfa. [ Conclusion ] Lignin Monomers deposition sites were mainly in the primary xylem and secondary xylem, primary phloem, it had the most lignin deposition at the bottom of alfalfa stem. There was a significant difference between the 2 kinds of lignin monomers in the stem of Alfalfa, and the thickness and proportion of S lignin monomer were more than that of G lignin monomer in pith and pith ray cell of alfalfa.