Multifunctional roles of structural and histochemical traits in Fabaceae galls in Brazil

Abstract Fabaceae stands out as the primary plant family hosting galls in Brazil. Based on data from Brazilian literature, we compiled and listed the structural and histochemical traits related to the development of 26 gall morphotypes induced in 13 Fabaceae species. The inherent plasticity of this plant family enables multiple functionalities and facilitates its adaptation to a wide range of environments. We hypothesize that the interaction between distinct host Fabaceae traits and their multiple functionalities offers galling herbivores a wide variety of structural and chemical resources. A current literature survey reveals that epidermal alterations, parenchyma homogenization, and cell wall lignification are the primary gall traits that confer a physical, mechanical, and biochemical combination, enabling the success of the gall inducer life cycle. The multiple functionalities of these traits may enhance the adaptability of Fabaceae galls in different environments. Furthermore, the range of possibilities offered by each structural peculiarity, in combination with chemical traits and the regulation of key enzymes in carbohydrate metabolism, indicates the existence of sophisticated physiological and biochemical relationships. Our data also reveal peculiarities of species within the subfamily Caesalpinioideae, which act as superhosts of galling herbivores and may serve as elegant models for future studies on galls in the Neotropical region. We provide insights into three Fabaceae host plant-gall inducer systems and encourage researchers to continue mapping their ontogenetic steps toward elucidating changes in standard developmental plant programs, while advancing our understanding of gall diversity.