Siri Fjellheim

Siri Fjellheim


  • Rektoratet

My Research focus on evolution of adaptation to temperate climate in grasses. The grass family is the most important plant family in the world and contain species like maize, rice, wheat and barley. This plant family alone provide more than 50% of the world populations calorie intake. My interest is in the Pooideae subfamily which dominate the grass flora in the Northern temperate regions. In northern parts of Europe, Asia and America more than 90% of the grasses belong to this subfamily. In our projects we study different aspects of adaptations to temperate regions and how they have evolved in the subfamily to facilitate the transition from tropical to temperate regions. The Northern temperate climate are characterized by strong seasonality with cold winters and mild summers. Crucial for plants in Northern temperate regions is to survive the low-temperatures encountered during winter. Freeze tolerance is the ability of plant tissues to survive below zero temperatures through biochemical and morphological adjustments. Although plants have some innate tolerance to a sudden exposure to frost, additional freeze tolerance can be induced through cold acclimation, i.e. an extended exposure to cold non-freezing temperatures. We study physiological and molecular aspects of cold adaptation (cold acclimation and resistance to sudden frost) and elucidate their role in evolution of adaptation to temperate regions in the grass subfamily Pooideae. Furthermore, timing of flowering is a crucial factor for reproductive success of flowering plants. In the seasonal climate of high latitudinal areas, the plants mainly make use of temperature and day length as queues to flower at the right time. This is controlled by two molecular pathways – the vernalization and photoperiodic pathways. Vernalization is the process where an extended period of cold (i.e. winter) triggers transition from vegetative to reproductive growth in plants. This is crucial to ensure flowering in the spring and not in a temporary warm period in the autumn. The plants also make use of day length to time flowering to the right time in spring – not too early to avoid spring frost and not too late to avoid summer drought. The most recent common ancestor of the Pooideae was of tropic origin and was most likely a short day flowering plant with no vernalization requirement. We study evolution of vernalization and daylength responses on physiological and molecular level to elucidate how the transition from a short day plant without vernalization requirement to a long day plant with vernalization requirement has contributed to Pooideaes success in temperate regions. I also do research on conservation genetics and population genetics of invasive species. Preserving the genetic identity of species in their local environment is fundamental in conservation genetics. We use genetic markers to develop site specific seed material for use in ecological restoration of degraded alpine landscapes in compliance with the Norwegian Diversity Act.