How do flowers know when to bloom?
Flowering at the right time is a key determinant of reproductive success for plants. As an adaptation to local climates many plant species show accelerated flowering after being exposed to cold temperatures, a phenomenon known as vernalisation. This is mediated by epigenetic gene regulation, a process that allows plants to memorise temporal signals over many cell cycles. Extensive research has identified a group of highly conserved proteins known as polycomb proteins to turn off the major floral repressor gene FLC during vernalisation. The vernalisation 1 (VRN1) gene has also been identified to affect FLC expression by a yet unknown mechanism. The main objective of the EU-funded 'Maintenance of cellular memory by the Arabidopsis VRN1 protein' (Vrnepigen) project was to gain a better understanding of VRN1 function. To achieve that, project partners used the method of chromatin immune-precipitation (ChiP) to identify the VRN1 binding sites on the FLC gene. They found that VRN1 binds the FLC gene affecting its expression pattern. Additionally, VRN1 binding was associated with aberrant chromatin levels. This finding indicated that vernalisation is affected by the organisation and turnover of histones, the proteins that package and structure the DNA in the nucleus. Overall, the Vrnepigen project has provided novel insight into the role of chromatin dynamics on gene regulation. The contribution of the study to understanding the mechanisms that govern the process of vernalisation will allow manipulation of crop flowering with profound economic implications in agriculture.
