Cellular bases of plant secretion: convergence of methods to integrate knowledge in structural botany and cell biology

Abstract

Secretory structures, considered natural factories of substances with ecological, economic and medicinal value, differ in morphology, location in the plant body and chemical composition of the produced substances. In plants, secretion is a complex process and can be divided into three phases: cytoplasmic synthesis, intracellular accumulation and removal of substances from the protoplast to the interior of intercellular spaces or to the organ surface. Understanding cellular specializations and their consequences for the secretory process requires integrative approaches in structural botany and cell biology, with the application of convergent methods in basic and advanced microscopy. Such studies are imperative, especially when considering the richness of species that produce bioactive substances, and the growing use of natural products as raw material for an increasingly diversified industry. The central theme of the current proposal is the interdisciplinary study of secretory structures, in order to characterize specializations at the cellular level and their implications for the secretory process. The project was arranged into five themes with different approaches and plant species, in which we intend to study: i) intraspecific variations in the ultrastructural organization of secretory tissues into sun and shadow modules focusing on the functional versatility of the secretory cell, ii) cell wall characteristics of mucilage-secreting cells and oil cells focusing on the cell wall architecture and secretion compartmentalization, iii) the signs of autotoxicity and cytoprotective mechanisms that precede the autolysis of terpene glands, iv) the cellular mechanisms associated with the fusion of secretory spaces, v) the ultrastructure of nuptial and extranuptial nectaries within the same flower and its implications for nectar features. Conventional techniques in structural botany and cell biology, under light and scanning and transmission electron microscopes, as well as immunohistochemistry and ultrastructural cytochemistry methods will be used. In addition, chemical analyzes of floral nectar will be performed. Results of great relevance to the studies of the biology of secretion in plants are expected, with the training of qualified human resources, scientific publications in wide circulation journals, in addition to the consolidation of partnerships with researchers in Brazil and abroad. (AU)