Plant growth regulators and environmental signalling regulating metabolic and molecular pathways involved on Coffea Arabica reproductive development

Abstract

The flowering of the coffee plant is a process that significantly impacts crop productivity, being of utmost importance to the coffee industry. One of the main challenges coffee growers face is the irregularity and asynchrony of flowering, which can compromise the quality and quantity of coffee produced. This thesis aims to deepen our understanding of the role of plant hormones in the reproductive development of coffee plants and to provide practical solutions to improve the management of this process. This thesis is divided into two main sections. The first section presents the introduction and theoretical framework, providing the necessary foundation for subsequent investigations (second section). This section includes a book chapter that reviews the role of plant growth regulators (PGRs) in reproductive development, linking them to coffee plants, and proposing suggestions for applying these regulators in the field. The first article in this section is a review exploring the role of FT and TFL1, key flowering genes, and their interactions with plant hormones, with a special focus on perennial plants. The second article presents the results of field experiments conducted to understand how the application of PGRs, specifically gibberellin (GA) and abscisic acid (ABA), influences the flowering of coffee plants at different stages of reproductive development, from induction to floral bud formation, as well as environmental factors. This study revealed how these PGRs affect the molecular pathways involved in coffee plant flowering and identified, for the first time, genes related to the biosynthesis, signaling, and degradation pathways of GA and ABA. Furthermore, this study highlighted the complex interactions between gibberellin, abscisic acid, and ethylene during floral bud development. With this thesis, we hope to provide a deeper understanding of how plant hormones regulate the flowering of coffee plants and propose methods to regulate these processes in the field. We aim to offer innovative technologies that can improve agricultural practices, address challenges related to reproductive development in perennial plants such as coffee, and contribute to the sustainability and productivity of the crop.