Developmental Anatomy of Galls in the Neotropics: Arthropods Stimuli Versus Host Plant Constraints

As natural microlaboratories, galls are elegant models to study plant cell fates. Each gall morphotype is the product of repetitive patterns in cell division and differentiation, which culminate in a neoformed multicellular organ. Gall morpho- genesis ruptures the patterns of cell polarization and expansion in relation to their host organs through cell redifferentiation, which results in changes in their function- ality. As so, gall tissues guarantee nutrition, protection and a favorable microenvi- ronment to the gall inducer. Sites of hyperplasia and hypertrophy are commonly reported for arthropod galls, and are commonly related to the feeding habits of each taxon. Nevertheless, there are some morphotypes in which the shapes are so pecu- liar that some other mechanisms must be involved, such as biochemical interac- tions, for instance. We revisit some Neotropical gall systems to check if the accumulation of phenolics is kept as one of the fi rst cell responses to the presence of the inducer and if it is related to the changes in cell polarity and axiality. The fi nal gall morphotypes require new spatial and developmental control of the host plant cells division and expansion, together with cell redifferentiation, but under the con- straints imposed by the host plant organs.