Ma Jianfeng, Zhou Xia, Ma Jing, Ji Zhe, Zhang Xun, Xu Feng
Beijing Key Laboratory of Lignocellulosic Chemistry,Institute of Material Science and Technology,Beijing Forestry University,100083 Beijing,China.
Microsc Microanal. 2014 Jun;20(3):956-63. doi: 10.1017/S1431927614000658. Epub 2014 Apr 15.
Confocal Raman microspectroscopy (CRM) has emerged as a powerful approach to visualize the compositional distribution in lignocellulosic biomass of cell walls. In this work, the applicability of CRM for imaging the topochemical correlation between lignin and hydroxycinnamic acids (HCA) in the Miscanthus sinensis internode was explored. Model compound [p-coumaric acid (PCA) and ferulic acid (FA)] analysis indicated that the band region from 1,152 to 1,197 cm(-1) can be used to characterize the distribution of HCA. Raman images calculated by integrating over the area intensity of characteristic spectral regions showed heterogeneous distribution of lignin and HCA at cellular and sub-cellular level. When overlaying the Raman image of lignin and HCA distribution, it was found that these two polymers were co-located in the middle lamella and secondary wall of corresponding cells. Raman images for the band intensity ratio (1,173 cm(-1)/1,603 cm(-1)) indicated a clear association between lignin and HCA distribution within morphologically distinct cell wall layers of sclerenchyma fibers and the parenchyma. This is the first time that the spatial correlation between lignin and HCA concentration has been illustrated by a microspectroscopy imaging approach. The results are of importance in extending the current understanding of lignin and aromatics topochemistry in herbaceous biomass.
共聚焦拉曼显微光谱（CRM）已成为一种可视化木质纤维素生物质细胞壁成分分布的强大方法。在这项工作中，研究了CRM对芒草节间木质素和羟基肉桂酸（HCA）之间拓扑化学相关性成像的适用性。模型化合物[对香豆酸（PCA）和阿魏酸（FA）]分析表明，1152至1197 cm⁻¹的谱带区域可用于表征HCA的分布。通过对特征光谱区域的面积强度进行积分计算得到的拉曼图像显示，木质素和HCA在细胞和亚细胞水平上呈异质分布。当叠加木质素和HCA分布的拉曼图像时，发现这两种聚合物共位于相应细胞的中层和次生壁中。拉曼图像的谱带强度比（1173 cm⁻¹/1603 cm⁻¹）表明，在厚壁纤维和薄壁组织形态不同的细胞壁层中，木质素和HCA分布之间存在明显关联。这是首次通过显微光谱成像方法阐明木质素与HCA浓度之间的空间相关性。这些结果对于扩展当前对草本生物质中木质素和芳香族化合物拓扑化学的理解具有重要意义。
