Galhas foliares em Byrsonima Spp. Kunth (Malpighiaceae): do laboratório para a sala de aula

Abstract

This thesis is divided into two sections: section I consists of three chapters dealing with the procedures, results, and implications of the scientific research on Byrsonima spp. and their galls, and section II consists of two chapters that linnks the gap between scientific research, scientific dissemination, and the teaching of Botany with a focus on the initial training of Basic Education teachers. Byrsonima coccolobilofia Kunth, B. variabilis A. Juss., and their associated galling organisms were studied here from phenological, anatomical, histometric, histochemical, and immunocytochemical approaches. We investigated the strategies of the associated galling organisms to manipulate the morphogenetic potential of the host plants toward the success of their life cycles. The characters of the two studied galls and the peculiarities of their life histories also inspired methodologies capable of making botanical knowledge up-to-date and accessible to future teachers of basic education and the general public. The creation of each teaching and dissemination strategy had the goal of bringing back the Scientia amabilis of Carolus Linneus to the rich field of new discoveries and had the partnership of undergraduate students of the Biological Sciences course at Universidade do Estado de Minas Gerais/Ibirité. The object of study is the galls, i.e., the structure that develop in response to parasitic organisms that can be viruses, bacteria, fungi, nematodes, mites, or insects. The ability to induce galls is an efficient strategy for herbivores using plants toward finding a microenvironment suitable for their establishment and nutrition, as well as protection against their natural enemies and environmental hazards. The development of the galls in plant tissues is influenced and coordinated by the galling organisms by means of factors not yet elucidated that redirect the cells to characteristic morphogenesis resulting in the differentiation or redifferentiation of cells at the site of gall formation. Phenological studies in the B. coccolobifolia-Cecidomyiidae galling system revealed the temporal occupancy dynamics and the strategies developed by the host plant to escape successive induction cycles. The synchronism between the gall induction phase and the leaf budding phenophase of the host plant was evidenced. The vegetative and reproductive phases of B. coccolobifolia are asynchronous with gall development, which characterized a possible escape strategy from the competition with Cecidomyiidae. The anatomical and histometric studies revealed that the insect galls present great specialization forming two tissue compartments. The outer tissue compartment assumes the function of storage and gall protection, while the inner tissue compartment is responsible for the direct nutrition of the gall. In the rust fungi gall, there is no alteration in the structure of the mesophyll of B. variabilis or the formation of specialized tissues. However, regarding chemical profiles, the histochemical and immunocytochemical studies revealed similarities in the location and distribution of metabolites in the leaves of the two species of Byrsonima and revealed a similar gradient of primary metabolites between insect galls in B. coccolobifolia and rust fungi galls in B. variabilis. The dynamics of cell wall components revealed alterations in the development of the gall structure, and in the nutrition and defense of the inducers. The immunolabeling of the epitopes of arabinans and galactans revealed similarities concerning the increased porosity of cell walls near the gall, favoring the traffic of substances toward the galling organisms. We assumed that the origin-destination of gall tissues, alterations in the distribution of metabolites, and dynamics of cell wall epitopes in response to gall development would be similar in the studied plants because they are congeneric species. Such a hypothesis was partially corroborated, considering that tissue specialization was evidenced only in the galls induced by the galling Cecidomyidae. However, the histochemical and immunocytochemical alterations as functions of the insect and the rust fungi gall establishment and development are very similar regarding the distribution of primary metabolites and cell wall dynamics. The interpretative devices created allowed a bridge between the knowledge produced in the academy and teacher training, giving to the post-graduation an active role in the formation of critical citizenship education, forming citizens capable of understanding the importance of science and its application in everyday life. Moreover, scientific dissemination outside academic environments links the academy-society gap with which we hope to achieve the ultimate goal of scientific literacy.