Env Exp Biol (2012) 10: 15–26

Variable effect of arthropod-induced galls on photochemistry of photosynthesis, oxidative enzyme activity and ethylene production in tree leaf tissues

Abstract

The aim of the present experiments was to determine the effect of arthropod-induced galls on photochemistry of photosynthesis, defense enzyme activity and ethylene production in host plant tissues. In total, 10 arthropod gall-inducer–host plant combinations, including seven tree species infected with five species of eriophyid mites, four aphid species and one sawfly species were analyzed. The presence of gall tissues differentially affected photochemistry of photosynthesis in non-galled adjacent leaf tissues. Localization of leaf vein pocket galls induced by Colopha compressa on leaves of Ulmus laevis resulted in photoinhibition of photosynthesis in parallel with decreased electron transport rate and increased non-photochemical quenching. The degree of infestation with eriophyid mite Eriophyes padi was associated with decrease in photochemical efficiency of photosystem II and concomitant increase in non-photochemical quenching in leaves of Prunus padus. Both peroxidase and polyphenol oxidase activity increased with increasing number of sawfly Pontania vesicator galls per leaf of Salix fragilis. Similarly, peroxidase activity in leaves of Acer saccharinum increased along with increasing level of infestation with Vasates quadripes. The presence of aphid Pemphigus spirothecae-induced petiole spiral galls resulted in significant decrease of both enzyme activities in leaf blades of Populus nigra with no changes in leaf petioles. Gall formation resulted in significant increase in ethylene production from leaf blade tissues of Populus nigra. The presence of leaf vein pocket galls on leaves of Ulmus laevis resulted in more than two-fold increase of ethylene production rate in affected leaf tissues. Increased rate of ethylene production was found also in other gall forming arthropod-host plant combinations. The variable effect of gall formation on host plant photochemistry of photosynthesis and oxidative enzyme activity might be explained by specific gall-inducer–related signals at the site of activity, in combination with specific endogenous plant signals involving ethylene.