CHARACTERIZATION OF ANATOMY,ULTRASTRUCTURE AND MICRODISTRIBUTION OF LIGNIN IN FORSYTHIA SUSPENSA

摘要

The features of Forsythia suspensa were described anatomically and morphologically in detail by light microscopy (LM) together with scanning electron microscopy (SEM). Fibre morphological determination showed that mean fibre length, width and cell wall thickness are 0.69 mm, 13.32 μm and 2.36 μm, and that the Runkel ratio and the ratio of length to width are 0.67 and 51, respectively. Vessel elements were found to be 0.59 mm in length and 30 μm in diameter. Wood anatomical characteristics indicated that the wood is mainly diffuse-porous with indistinct growth ring boundaries. Helical thickenings and alternate intervessel pits are present on vessel cell walls. Ray cells are predominantly uniseriate and only seldom biseriate. Both the confocal microscopy (CLSM) and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA) were used to investigate the distribution of lignin between and within cellular elements. Confocal images illustrated stronger autofluorescence from fibres compared to vessels, suggesting a high level lignification of fibres. Confocal microscopy also provided additional information presenting that a high level of lignin autofluorescence in the cell corner middle lamella (CCML), with lower levels of fluorescence in the compound middle lamella (CML) and the S2 region of fibre secondary wall. The data from SEM-EDXA demonstrated that lignin concentration ratio in different morphological regions of fibre walls is 1.25 (CCML):1.10 (CML):1 (S2). These results further confirmed the information obtained from CLSM.