The Control of Bud Break and Flowering Time in Plants

In perennial plants, the release of bud dormancy, with subsequent flowering, resembles the vernalization process of Arabidopsis thaliana and cereals. Especially for perennial crops from temperate regions, dormancy is an important adaptive trait for both survival and growth. Exposure to sufficient chilling during winter dormancy ensures the normal phenological traits in subsequent growing periods. Here, we compile research data on mechanisms controlling the overlapping developmental processes that define dormancy induction, maintenance and release, bud burst and flowering. Recent findings highlight the relevance of genome-wide epigenetic modifications related to dormancy events, and more specifically the epigenetic regulation of DORMANCY-ASSOCIATED MADS-box, FLOWERING LOCUS C and FLOWERING LOCUS T genes, key integrators of vernalization effectors on flowering. The roles of plant growth regulators in controlling bud break and flowering are discussed in relation to epigenetic mechanisms. A growing body of knowledge demonstrates that epigenetic regulation plays a key role in these processes in perennial horticultural and forestry plants. We discuss the most relevant molecular and genomics research that contribute to better understanding of the dormancy process and pave the way to precise manipulation of dormancy-related horticultural traits, such as flowering time. Finally, some of the challenges for further research in bud dormancy and consequences in agriculture are discussed within the context of global climate change.