TEM investigation of tannins and chloroplast structure in needles of damaged silver fir trees (Abies alba Mill.)

As part of investigations on the effect of air pollution on plant anatomy, we examined the condition of tannins and chloroplast structure in damaged fir trees (Abies alba Mill.) at Risnjak National Park. Two populations were chosen for needles sampling: one at the Risnjak site with trees having 20%,45% and 85% damage, and the other at the Donja Dobra site (control locality) with relatively healthy trees having 5% to 10% damage. Current and previous-year needles were fixed with glutaraldehyde and osmium tetroxide, and then the condition or ultrastructure of tannins and chloroplasts were examined by transmission electron microscopy (TEM). The tannins were shown to be granular and arranged in thin or thick ribbons. The chloroplasts were first somewhat rounded and then round or irregular in shape, with reduced and swollen thylakoids, especially those of the grana, increased numbers of plastoglobuli, large lipid droplets/accumulations, and vesiculation of the cytoplasm. These symptoms were more frequent in previous-year than in current-year needles. All these alterations can be attributed to air pollution.