The effect of leaf galls of Cynipidae on accumulation and biosynthesis of plant amines in oak trees

Abstract

Polyamines (PAs) are involved in plant response to abiotic and biotic stresses, however, their role in biochemical insect-plant interactions is not clear. Therefore, we compared the involvement of polyamines and key enzymes of their biosynthesis in gall formation process. The present study had used galls on oak leaves caused by asexual generation (♀♀) of three Cynipidae species, namely Cynips quercusfolii L., Neuroterus numismalis (Fourc.) and N. quercusbaccarum L., as a model. The obtained results indicate that gall formation on oak leaves affected amine content, but intensity of the changes in their levels were strongly dependent on the insect species. Nevertheless the downward trend was dominant among those changes. Changes in the activity of lysine decarboxylase (LDC), tyrosine decarboxylase (TyDC) and ornithine decarboxylase (ODC) usually corresponded with the direction of changes in polyamine contents. Several cases of divergence between changes in amine levels and the rate of their biosynthesis may suggest the involvement of other regulation mechanisms such as: arginine decarboxylase (ADC) and S-adenosylmethionine decarboxylase (SAMDC) as well as amine oxidases involved in its catabolic pathways. Thus, the future studies on biochemical mechanism of regulation of PAs accumulation during galls formation should be focused on importance of these enzymes.