The differences in the degree of acetylation between the polymers
affected PAL and POD enzymatic activities when they were
applied as foliar spray in tobacco leaves. The highest PAL activity
was found with the more acetylated polymer (CH-36) in all three
concentrations tested, whereas POD activity was above the control
with all the three concentrations of the less acetylated polymer
(CH-12). A similar behavior has been previously demonstrated
for the same enzymatic markers in tobacco roots when the same
chitosan polymers were directly applied to this organ in tobacco
plants [24]. Thus, there is a clear influence of the degree of acetylation
of chitosan on the induction of enzymatic defense responses,
at least for these two enzymes, when chitosan derivatives are directly
applied to the organ. In addition, in the present and prior
studies, PAL and POD activities were affected differently with different
applications [24]. Former authors reported that augmentation
in the polymer’s degree of acetylation caused rise in
enzymatic activity for PAL and POD in wheat leaves when directly
applied [21]. The results of this study are in agreement with previous
studies on PAL but are opposed for the influence on POD activation.
This difference might be related to working with different
plant species, especially when these species belong to different
plant groups as, for instance, monocots and dicots.
When chitosan was added to the substrate, changes in enzymatic
activity in tobacco leaves were the result of the systemic
induction of the defense signal because the elicitors were only in
contact with the roots. When treatments were added to the plant