Seminars

We are comparing the biochemical mechanisms by which plants synchronise their life cycles to the changing seasons. Arabidopsis thaliana is a model annual plant, which flowers only once in a life cycle that typically lasts for a few months. We have studied the regulation of transcription factors that promote flowering specifically in response to the long day lengths of summer. We have shown that this response depends on two layers of regulation involving circadian-clock control of transcription and protein degradation that is controlled by light. As a perennial species, we have used Arabis alpina, which is a close relative of A. thaliana. This species lives for many years, flowers each year and absolutely requires exposure to winter temperatures for flowering. We have shown how specific transcription factors involved in temperature response are differently regulated between these annual and perennial species, and that this enables the perennial species to flower each year. Evolution of the regulation of these genes involves changes in chromatin regulation. We are exploring natural variation in this process in Arabis alpina and how vernalization response intersects with the age of the shoot to influence flowering time. I will discuss the mechanisms that confer these seasonal patterns of flowering and how they have evolved.