Thirty years of research on nectar biology at the University of Siena – much more than a reward for insects

This article outlines the most significant stages of research on nectaries, nectar, and plant-pollinator relationships at the University of Siena. The initial research began in the mid-1990s, focusing on the structure-ultrastructure and functioning of nectaries for approximately a decade. Results from these studies revealed the peculiar organization and development of nectaries and highlighted and clarified the process of nectar resorption and its functions. Subsequently, research progressed to studies on the chemistry and biochemistry of nectar, ultimately aiming to understand how these aspects influence plant-pollinator relationships. This part of the research highlighted that specific nectar secondary metabolites affect pollinator behaviours that are important in the pollination process including pollinator mobility, time spent on a flower, memory and learning ability. The chemistry of gymnosperm pollination drop was also indagated opening interesting hypotheses on the evolution of these secretions and of insect pollination in angiosperms. Future research aims to better understand plant-pollinator interactions investigating pollination networks and the role of microorganisms inhabiting nectar. The diversity and complexity of plant-pollinator interactions, as well as the challenges related to their increasing degradation, are topics of dissemination to the local community of citizens thanks to specific projects developed in very recent years.