Nov 1, 2018 // Developing under a changing environment: cold acclimation and vernalization in Brachypodium distachyon

Boris Mayer, PhD Candidate, Dept. Plant Science, McGill University

​With the onset of climate change, it has become increasingly relevant to understand how plants respond to changing environmental conditions. Yet, temperate plants regularly face seasonal change and, to persist in these conditions, have adapted by adjusting their stress tolerance, phenology and development. Understanding how temperate plants follow seasonal cues during their development can help elucidate adaptation in plants. Cold acclimation (CA) and vernalization (VRN) are processes that ensure persistence in temperate climates by regulating freezing tolerance and flowering time respectively. However, how these two processes are integrated into a coordinated developmental response remains poorly understood. The model grass Brachypodium distachyon has emerged as a model to study CA and VRN in temperate cereals. By identifying key seasonal cues that occur within the native range of the species, we designed a diurnal freezing treatment (DF) that combines prevailing summer-to-winter transition signals. Under DF, B. distachyon accessions of different climatic origins manifest coordinated and novel cold acclimation and vernalization responses. Altogether, our results demonstrate a direct link between CA and VRN, and that typically used constant-temperature cold treatments induce an “over-vernalized” molecular state at the expense of freezing tolerance. This work also stresses the importance of reproducing natural signals in laboratory conditions.