UC Davis

Annual plants possess the ability to perceive a broad spectrum of signals from their external and internal environments, enabling them to flexibly regulate flowering timing and optimize this crucial reproductive transition in seasonal conditions. However, the mechanisms underlying most of the seasonal flowering responses observed in the natural environments remain elusive, despite the wealth of molecular knowledge related to flowering-regulating genes and pathways. This dissertation presents two case studies related to seasonal flowering responses and explores the underlying molecular mechanisms. In the first chapter, I investigate vernalization-induced flowering synchrony in Arabidopsis thaliana. My findings unveil the contributions of both leaf-based and non-leaf-based regulatory mechanisms to flowering synchrony, emphasizing the critical role of inter-organ crosstalk. The second chapter explores the molecular mechanisms underlying the long-day photoperiodism of annual Mimulus guttatus. Using QTL mapping and RNAseq, I reveal distinct molecular mechanisms capable of yielding similar photoperiodic responses, highlighting the flexibility of flowering pathways. Lastly, I examine differential transcriptomic regulations in response to constant and diel temperature fluctuations using Mimulus guttatus. This study is a component of a broader project that focuses on how plants interact with the real-world environment, which is crucial for achieving a comprehensive understanding of the seasonal flowering responses observed in natural conditions. Overall, these studies establish a foundational understanding of seasonal flowering responses and highlight the necessity of exploring interplays among pathways and among plant organs to obtain comprehensive insights into these phenomena.