Functional gradients in insect gall tissues: Studies on neotropical host plants

Abstract

The first mechanism by which the insect recognizes its host plant was not elucidated yet. Once the induction occurs, the plant, in general, responds by the redifferentiation of tissues with typical features and functions of a new organ. These tissues may guarantee adaptive advantages to the galling insect against natural enemies, microenvironmental stresses, and also provide adequate nutrition. Moreover, the formation of the final gall body, i.e., its morphological design, is directly related to the formation of the tissues of the gall. This is especially true for the reserve tissue or the outer cortex, and the nutritive tissue or inner cortex. Interesting questions to be addressed are how these tissues differentiate, and whether cytological and histochemical gradients are developed in galls. In fact, these gradients seem to occur in the majority of the galls, and their formation may be related to the formation of reactive oxygen species (ROS) since the onset of the interaction.