Application of Scanning UV Microspectrophotometry to Localise Lignins and Phenolic Extractives in Plant Cell Walls

Abstract

The localisation of lignin and phenolic extractives in woody tissue was determined using scanning UV microspectrophotometry. This improved cellular analytical technique enabled direct imaging of the topochemical lignin distribution within individual cell wall layers with a resolution of 0.25 µm 2 . Selected softwood (Picea abies), hardwood (Fagus sylvatica, Entandrophragma cylindricum, Prunus serotina) and monocotyledon (Phyllostachys edulis) sections of 1 µm thickness were scanned at a fixed wavelength and evaluated with the "APAMOS" software. This approach allowed the distribution pattern of lignins and aromatic extractives within the cell wall to be visualised simultaneously. The method was found to be ideally suited to the study of their subcellular distribution in plant cell walls.

Topochemical analyses of furfuryl alcohol-modified radiata pine (Pinus radiata) by UMSP, light microscopy and SEM

“…The highest absorbances occur in the area of the CML and the CC as previously described for W untr (Koch and Kleist 2001;Koch and Grünwald 2004) and also for thermally (Mahnert et al 2013) and hydrothermally modified wood (Andersons et al 2016). For the W untr tissue, the following UV absorption data (A 280 nm ) are typical: 1.22 for the CML, 1.48 for the CC and lower, slightly varying values for the S2 layer (0.69-0.95).…”

“…The cell wall layers (S2, CML and CC) of W untr show typical UV spectra of lignified softwood tracheids, with the characteristic A max at λ 280 nm attributed to the strongly absorbing guaiacyl-type units (Musha and Goring 1975;Fujii et al 1987). The different absorbance intensities at λ 280 nm are strongly correlated to the lignin concentration, with the highest amount in the CC (Koch and Kleist 2001;Koch and Grünwald 2004). In this case, the absorbance in the CC of W untr is 1.6 times higher than in the S2 (Table 2).…”

“…UMSP is an established analytical technique which enables the direct imaging of lignin distribution and lignin modification in the course of biodegradation and technological delignification within individual cell wall layers in situ Scott et al 1969;Saka et al 1982;Fukazawa 1992;Koch and Kleist 2001;Koch et al 2003a;Koch et al 2003b;Koch and Grünwald 2004;Rehbein and Koch 2011;Koch and Schmitt 2013;Aguayo et al 2014;Kojima et al 2014;Bianchi et al 2016;Ehmcke et al 2016). The π electron-rich lignin shows UV maxima at around λ 212 nm and λ 280 nm Goldschmid 1971;Fukazawa 1992).…”

Effect of Physisporinus vitreus on wood properties of Norway spruce. Part 1: Aspects of delignification and surface hardness

“…The topochemical analysis was carried out with a UMSP 80 microspectrophotometer (Zeiss, Jena, Germany) equipped with a scanning stage enabling the examination of image profiles at ls280 nm that represents the absorbance maximum of softwood lignin (Koch and Kleist 2001). For the field scans, areas of approximately 40=40 mm 2 were scanned line by line using Apamos ᭨ software (Zeiss, Jena, Germany).…”

“…Accordingly, cellular UV-microspectrophotometry (UMSP) was applied to characterize the delignification process of P. vitreus on Norway spruce after incubation times of up to 9 weeks. The UMSP technique is well suitable for detecting the topochemical distribution of lignin at a subcellular level (Koch and Kleist 2001;Irbe et al 2006;Kim et al 2008;Lehringer et al 2008;Prislan et al 2009). Bauch et al (1976) applied UMSP successfully to investigate topochemical delignification caused by fungal decay in woody tissue.…”