Dormancy or Cold development? A comparative genetic study on peach vegetative buds

This thesis presents a comprehensive study on the regulation of bud development and dormancy in peach trees, a critical aspect of fruit tree biology with significant implications for agricultural practices and breeding strategies. The research integrates advanced transcriptomic, hormonal, and molecular techniques to explore the dynamic nature of bud development during winter dormancy and the complex interplay of genetic, environmental, and hormonal factors influencing this process. Chapter 1 delves into the concept of winter dormancy in fruit trees, challenging traditional definitions and introducing the term 'cold development' to better describe the active and dynamic processes occurring within peach buds during the cold months. This chapter emphasizes the need for a revised conceptual framework, reflecting the ongoing growth and developmental activities during winter dormancy, shaped by environmental cues and physiological changes. Chapter 2 focuses on the comparative analysis of vegetative and floral peach buds, highlighting the conserved and distinct pathways governing their development. This analysis reveals the active nature of dormancy, characterized by hormonal dynamics and transcriptomic changes tightly regulated by environmental factors. The findings suggest a state of readiness for spring growth and point towards synchronized regulation of dormancy and bud break mechanisms. Chapter 3 explores the roles of MADS-box genes, specifically the SHORT VEGETATIVE PHASE (SVP) homologs and Dormancy-Associated MADS-box (DAM) genes, in the regulation of dormancy and flowering time in peach. Using transcriptomic data, BiFC assays for protein-protein interaction studies, and in silico analyses, the study unravels the complex molecular networks that regulate bud dormancy. The results highlight selective interactions of SVP with DAM genes, revealing its central role in the dormancy-related regulatory network. Overall, this thesis contributes to a deeper understanding of the molecular and physiological mechanisms underlying bud dormancy and development in peach trees. The insights gained from this study have potential applications in improving plant resilience and productivity, particularly in the context of climate change. The research advocates for continued exploration of the 'cold development' processes in fruit trees, which could transform horticultural strategies and enhance global fruit cultivation.