Abstract: Autofluorescence in the cell walls of Phyllostachys pubescens Mazel culms was analyzed by ultraviolet fluorescence microscopy, mierospectrofluorometer and histoebemical staining before and after respective treatment with ammonia, NaOH and H202/HAC. All tissues of the bamboo eulm showed blue autofluorescence under ultraviolet irradiation. With the treatment of ammonia, the tissues increased their fluorescence intensity, among which those rich in ferulie acid changed their color into green, the peak of fluorescence emission spectra shifted from 470 nm to 510 nm. Nevertheless, the fluorescence intensity of all tissues decreased dramatically after the treatment of NaOH. With H202/HAC treatment, the lignified tissues remained strong blue autofiuorescence, while the fluorescence from unlignified tissues disappeared. The results indicated that protoxylem vessels had already showed lignification before phloem and metaxylem formed in the tissues; femlic acid was widely distributed in the young tissues of bamboo shoot, the content of which decreased with the progress of the lignitieation. It is further confirmed that H202/HAC treatment is an effective method to discriminate the phenolic acids bound to hemicelluloses from the phenolies existed in the lignin molecules.

Key words: Autofluorescenee, Fluorescence emission spectra, Phenolic acids, Lignin, PhyUostachys Pubescens