Histochemical and biochemical approaches to the study of phenolic compounds and peroxidases in needles of Norway spruce (Picea abies)

The three youngest age-classes of needles of Norway spruce (Picea abies) we re collected from four sites in the Krusne Hory Mountains (Czech Republic) characterized by different levels of damage caused by environmental polluti on. Histochemical methods did not reveal any differences in localization of phenolics among the needles. Mesophyll cells close to the epidermis of nee dles and cells around resin ducts and substomatal cavities often accumulate d higher amounts of phenolics than the rest of the mesophyll cells, but thi s was independent of age and damage. Needles of different age- and damage-c lass did not show any marked changes in general lignification pattern. Howe ver, a lower intensity of histochemical detection of lignin was observed in needles from the most damaged site. This finding was confirmed by chemical analysis using thioglycolic acid. Generally, the amount of lignin in mesop hyll cells was lower in damaged trees than in healthy ones. Using the Folin -Ciocalteau method, no significant differences in the total content of phen olics were observed in the needles, although HPLC revealed marked alteratio ns in the forms of seven phenolic acids. Concentrations of conjugated forms of phenolic acids testers and glycosides) were higher in damaged needles ( 255.9 mu g g(-1) f. wt) than in healthy needles (189.8 mu g g(-1) f. wt). B y contrast, content of esterified phenolic acids incorporated into cell wal ls was higher in needles from healthy trees (101.1 mu g g(-1) f. wt) than i n damaged needles (78.3 mu g g(-1) f. wt). Marked differences were also obs erved in the activity of soluble peroxidases, although the activity of ioni cally bound forms was approximately the same in healthy and damaged needles . The total amounts of chlorophylls and carotenoids decreased as environmen tal damage increased.