Galls are plant structure induced in response to stimuli of a gallinducing organism. Euphalerus ostreoides induces galls on the adaxial surface of leaflets directly on secondary veins of Lonchocarpus muehlbergianus. Anatomical analyses were performed to compare healthy leaflets, immature and mature gall tissues. Histochemical tests for detection of phenolic derivatives, flavonoids, lignins, lipids and starch were performed to check the chemical impact of gall-inducing action. The lost of sinuosity of epidermal cells, the neoformation of trichomes, of conducting cells, and fibres were the most conspicuous plant responses features to gall induction. Mesophyll hiperplasia with maintenance of tissue stratification, and accumulation of lipids, starch, flavones, flavonols and flavanones in gall tissues were observed. Nevertheless, the formation of oxonium salts by the reaction with sulfuric acid only in gall tissues was a remarkable feature. The results suggested that L. muehlbergianus was submitted to a high oxidative stress induced by the action of E. ostreoides. It was possible to conclude that the structural and chemical alterations observed were considered as plant defensive reactions against herbivory and adaptive mechanisms that favor the galling insect establishment within plant tissues.
anatomy; Euphalerus; histochemistry; Lonchocarpus; plant gall
