Autofluorescence-decrease phenomenon of woody cell in Lophira alata

Abstract

Abstract Background: Fluorescence is an intrinsic property of lignin. However, the autofluorescence of Lophira alata (L. alata) was found to be almost invisible during an occasional fluorescence observation experiment. The purpose of this study was to investigate the reason why lignin autofluorescence is invisible in L. alata. Results: Herein, the autofluorescence microscopy, diffuse reflection spectra and UV-Vis absorption spectra of L. alata have been performed. In order to recognize the relationship between autofluorescence phenomenon and anatomical structure, themacroscopic, microscopic and ultramicroscopic characteristics of L. alata are also examined. Results show that both the longitudinal parenchyma and the rays are rich in extractives. Moreover, these extractives have infiltrated into the vessels and fibers. The autofluorescence of the wood becomes increasingly clear after the benzene–alcohol extraction treatment. Meanwhile, UV-Vis absorption spectrashow that the extractives from L. alata have a strong absorption to light at a wavelength range of 200-500 nm. Conclusions: The complex compounds like polyphenols or terpenoids contained in the rich extractives of L. alata are likely to affect the autofluorescence of lignin.