Env Exp Biol (2011) 9: 29–36

Gall midge Rhabdophaga rosaria-induced rosette galls on Salix: morphology, photochemistry of photosynthesis and defense enzyme activity

Abstract

Gall midge Rhabdophaga rosaria L. induces neoplastic formations on vegetative buds of Salix. Changes of chlorophyll content, chlorophyll a fluorescence, ascorbate peroxidase, polyphenol oxidase and peroxidase activity were analyzed in gall-leaves in comparison to adjacent control leaves in order to understand the nature of physiological changes caused by the gall-former. Chlorophyll content (R = 0.93), maximum photosynthetic efficiency of photosystem II (F_V/F_M; R = 0.83) as well as photosynthetic performance (R = 0.89) decreased in gall leaves from outer part towards the centre of the gall. Non-photochemical quenching increased in parallel with decrease in F_V/F_M towards the centre of the gall. Both peroxidase and polyphenol oxidase activity increased in gall leaves. In contrast, ascorbate peroxidase activity decreased with distance from the outer part of the gall. It is concluded, that the activity of the gall former affects both photosynthesis- and defense-related characteristics in galled leaf tissues. High activity of oxidative enzymes in a rosette gall tissues offers better protection of a gall-former against general herbivores and pathogens.