Developmental Responses to Fluctuating Light Regimes

Plants in nature experience a range of light intensities and spectral properties due to changes in sun angle and cloud cover in addition to shading from overlapping leaves and neighboring plants. Therefore, leaves are subjected to spatial and temporal gradients in incident light, which has major consequences for photosynthetic carbon assimilation. To date, the majority of studies examining acclimation to fluctuating light conditions have been carried out on plants grown under constant intensities of light and swapped to a simple light pattern (consisting of one or more step changes in light intensity of different frequencies). Under these light conditions, acclimation responses have often been monitored over a period of several days. Although this approach is powerful for studies on the mechanisms of dynamic light acclimation, it fails to recognize the importance of how plants developmentally acclimate to growth under fluctuating light intensities, such as those found in the natural field environment. Vialet-Chabrand et al. () mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). High and low light intensities, delivered via a realistic dynamic fluctuating or square wave pattern, were used to grow and assess plants. Plants subjected to square wave light had thicker leaves and greater photosynthetic capacity compared with fluctuating light-grown plants. This, together with elevated levels of proteins associated with electron transport, indicates greater investment in leaf structural components and photosynthetic processes. In contrast, plants grown under fluctuating light had thinner leaves and lower leaf light absorption, but maintained similar photosynthetic rates per unit leaf area to square wave-grown plants. Thus, developmental acclimation to fluctuating light intensity apparently influences plant performance under dynamic light conditions, such as those experienced in natural environments.