INFLUENCE OF DROUGHT STRESS, ENDOGENOUS STRIGOLACTONES AND MICROPEPTIDES ON GLYCOALKALOID BIOSYNTHESIS IN TOMATO

Plant-derived metabolites represent a valuable resource for industrial applications, providing eco-friendly alternatives to conventional agrochemicals and inspiring the development of novel drugs based on natural defense mechanisms. Tomato (Solanum lycopersicum L.) is among the most widely cultivated crops globally, and its large-scale production generates considerable amounts of leftover biomass that remains enriched in bioactive compounds. A prominent example is represented by steroidal glycoalkaloids (SGAs), secondary metabolites that accumulate at high levels in tomato green tissues, where they constitute a crucial component of the plant’s chemical defense against pathogens and herbivores. In addition to their well-established antimicrobial properties, SGAs have recently been linked to potential benefits for human health, making them highly attractive for both agricultural and pharmaceutical applications. Their abundance in tomato vegetative biomass thus represents an underexplored opportunity for waste valorization. However, since the accumulation of secondary metabolites is strongly shaped by environmental cues and hormonal signaling, deciphering the underlying regulatory networks is fundamental for both improving plant adaptation to stress and recovering these compounds for industrial exploitation. Beyond physiological regulation, novel biotechnological strategies are emerging that can modulate plant secondary metabolism. Recent studies have identified unconventional classes of small signaling peptides, some of which originated from non-coding genomic regions. Among these, microRNA-encoded peptides (miPEPs) have emerged for their ability to upregulate the abundance of their corresponding miRNA, thereby modulating downstream gene networks without requiring genetic engineering. This PhD project investigates environmental, hormonal, and molecular factors modulating SGA biosynthesis in tomato, with the broader aim of developing strategies to control their accumulation in green biomass. Specifically, it focuses on three regulatory layers: (i) drought stress, given its growing impact on global crop productivity and its broad reprogramming effect on plant metabolism; (ii) strigolactones, a class of plant hormones involved in architecture and stress responses but with largely unexplored roles in secondary metabolism; and (iii) miPEPs, as innovative tools for fine-tuning metabolite production and tomato stress resilience. By integrating physiological analyses with biotechnological approaches, this work aims to unravel the multilayered regulatory networks controlling SGA metabolism and to lay the groundwork for future applications in sustainable agriculture, pharmaceutical development, and biomass valorization.