Chromatin-mediated regulation of flowering time

Chromatin remodelling plays a crucial role in the establishment and maintenance of specific gene expression patterns associated with plant developmental transitions. For that reason, one of our main interests is to understand how epigenetic changes participate in the regulation of floral initiation and germination, and how environmental changes influence the structural dynamics of chromatin and affect developmental gene expression patterns. To accomplish these tasks we are using a combination of genetic, molecular and functional genomics approaches directed to identify and characterise master genes and regulatory circuits involved in the control of these developmental processes.

During recent years our lab has got a deeper insight in the epigenetic mechanisms that participate in the regulation of the floral transition through the molecular and genetic characterization of several Arabidopsis mutations affecting subunits of the plant SWR1 chromatin remodelling complex, which catalyses the exchange of H2A histone by the H2A.Z variant and that regulates flowering time in plants. We have characterized the EARLY IN SHORT DAYS 1 (ESD1) locus, encoding ACTIN-RELATED PROTEIN 6 (AtARP6), a nuclear protein similar to conventional actin, and also the AtSWC6 locus, that encodes a zinc finger- harbouring protein. Both proteins are part of the SWR1 complex and mutations in the corresponding genes cause an acceleration of flowering. In addition, we are studying AtSWC4 and AtYAF9-like proteins, whose yeast orthologues are present in the SWR1 complex and are shared by the histone acetyl transferase complex NuA4, indicating a possible functional interplay between these two complexes. We have demonstrated that AtSWC4 and AtYAF9 control flowering time and other developmental responses.

Inappropriate flowering time in cultivated species results in negative impacts in crop yield. It is our interest to translate the knowledge gained in Arabidopsis to close relatives such as Brassica napus or B. rapa oilseed crops. We are deepening in the chromatin-mediated regulation of developmental traits affecting crop yield in Brassica crops through the functional characterization of homologues of NuA4 complex subunits and other chromatin remodelers like the histone H3 lysine 27 demethylase ELF6, a key epigenetic regulator of flowering time. In the context of SYBRACLIM (FACCE-JPI ERANET Climate Smart Agriculture project), we are also evaluating the impact of climate variability on developmental traits and its effect on yield stability in Brassica crops.