Abstract

The correct timing of flowering is crucial for reproductive success. Genetic analysis in Arabidopsis thaliana has identified an integrated regulatory network that controls the timing of this developmental switch in response to seasonal cues. The Dean lab has focused on how prolonged cold promotes flowering. This process is known as vernalization and it aligns flowering with spring. We have dissected the mechanistic basis of vernalization in Arabidopsis through identification of mutants, analysis of the corresponding genes, chromatin biochemistry and more recently, computational modelling.

Central to vernalization in Arabidopsis is the quantitative regulation of a floral repressor gene, FLC . Quantitative variation in FLC determines whether plants require vernalization. Quantitative epigenetic silencing of FLC determines how long a winter is required. Dissection of both processes has led into the study of a set of antisense transcripts at the FLC locus, collectively called COOLAIR . Differentially processed forms of COOLAIR are associated with different FLC chromatin states. The chromatin modification, transcription and antisense transcript processing are co-transcriptionally coupled resulting in feedback loops that reinforce high or low expression states at FLC . The talk will describe our current understanding of these mechanisms.