高粱茎杆中木质素分布的显微技术研究

Study on Microscopy Techniques for Identifying Lignin Distribution in the Stem of Sorghum

摘要: 本文以禾本科植物高粱[Sorghum bicolor (L.) Moench]为研究材料，采用Wiesner反应、Mäule反应、番红染色及三种自发荧光信号对茎秆中的木质素进行定位，以探讨禾本科植物组织中的木质素鉴定方法。观察结果显示，Wiesner反应结果与番红染色的可见光观察结果一致，即木质素主要分布在高粱茎的表皮、机械组织、木质部和维管束鞘的细胞壁中，在细胞水平上主要分布在胞间层和角隅处。番红染色的荧光信号和自发荧光也都显示上述部位有较高的木质素含量，而且薄壁细胞壁的荧光信号比上述染色的可见光信号更清楚。Mäule反应结果显示紫丁香木质素主要沉积在维管束鞘的外层细胞的次生壁，而不是内层细胞及导管的胞间层和细胞角隅处。以上结果表明，进行禾本科植物高粱中总木质素鉴定，可取的染色方法是Wiesner反应与番红染色，结果准确且操作简单；自发荧光方法应采用蓝光激发产生的绿色荧光信号进行鉴定，能排除酚类物质的干扰；Mäule反应能有针对性的鉴定紫丁香基木质素。

Abstract: Distribution of lignin in the stem of sorghum [Sorghum bicolor (L.) Moench] was examined by the visible light microscopy coupled with the Wiesner and Mäule color reactions and by autofluores-cence microscopy to provide effective and reliable methods for identification of lignin distribution in gramineous plants. Transverse sections stained with Wiesner reaction and safranin both showed that epidermic cells, mechanical tissue, vascular bundle sheaths and vascular bundles were ligni-fied. The middle lamella and cell corner appeared to contain more lignin than the secondary wall. Fluorescence microphotographs of sections stained with safranin and unstained demonstrated not only the tissues above contained lignin, but parenchyma cells showed bright autofluorescence. Mäule reagent staining showed that lignin in secondary walls of vascular bundle sheaths was rich in syringyl lignin, whereas middle lamellae and cell corner of vascular bundle sheaths and xylem cells lacked syringyl. The present study suggested that Wiesner reaction and safranin staining may be effectively applied in determining the distribution of lignin in cell walls of sorghum. Mäule reaction provides a rapid and sensitive estimate of syringyl lignin distribution. Autofluorescence examination under blue light excitation was sensitive and effective technique for total lignin dis-tribution in cell walls of gramineous plants.