Co-evolution of Shade Avoidance and Response to Photoperiod in Arabidopsis Thaliana

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Pigliucci0089493This project aims at studying the evolution of plants' responses to two environmental factors, daylength and spectral light quality, using the weedy species Arabidopsis thaliana. The problem is to understand how plants integrate different environmental signals and if they "respond" appropriately by adjusting their life history to maximize their fitness. Daylength and light quality were chosen because they are important cues the plant uses to assess environmental conditions. Daylength is an indicator of seasonal changes, and can be used by plants to determine the optimal period of flowering during the spring or summer (depending on the latitude). Light quality (measured as the ratio between red and far red light) has been demonstrated to be an indicator of the density of the surrounding vegetation, and presumably the intensity of competition for light. This research will include a field component during which plants will be studied and collected from their natural environment along a latitudinal gradient from southern to northern Europe (the natural habitat for Arabidopsis). A molecular analysis will then be carried out to estimate how closely related the collected populations are to each other. Finally, a series of greenhouse experiments will be conducted to measure how the plants react to different combinations of daylength and light quality.This kind of study is important to understand if and how natural selection can match a plant's appearance and life history to the challenges posed by the environment. Because Arabidopsis has been intensively studied from a molecular perspective, knowledge of its ecology and evolution can be integrated with already published studies to achieve a better comprehension of the biology of the whole organism. Since this plant is also a close relative of economically important species such as broccoli, cauliflower and mustard, the knowledge gained by studying Arabidopsis may have direct applications for crop improvement.