Exploring UVA radiation effects on plant growth,photosynthesis and leaf light acclimation.

Ultraviolet (UV) radiation strongly impacts on plant growth and development. UVA (315-400nm) accounts for ~95% of solar UV radiation at sea level. However, many effects of UVA radiation on plants remain unknown, due to untargeted experimental approaches and limited availability of narrow-band UVA lamps in the past. The aim of this project is to obtain a comprehensive understanding of how UVA affects plant growth, leaf photosynthesis and light acclimation. Traits pertaining to plant growth and function such as biomass production, plant morphology (i.e. plant height, leaf area and leaf thickness), and leaf biochemical compounds will be measured under different UVA and photosynthetically active radiation (PAR) intensities to determine interactions between UVA and PAR; different species will be used to investigate the species specificity of plant responses to UVA. Instantaneous leaf photosynthesis responses to UVA will be measured to assess how strongly photosynthesis changes with different intensities and spectra of UVA radiation. In addition, the effects of long-term UVA exposure on leaf-level photosynthetic acclimation will be explored, by using an array of tools in leaf photosynthetic gas exchange and chlorophyll fluorescence. Furthermore, it will be explored to what extent leaf acclimation to UVA can induce photoprotection under abiotic stress (i.e., high light). Changes in flavonoids, carotenoids, reactive oxygen species (ROS) and non-photochemical quenching (NPQ) will be measured to quantify changes in photoprotection upon acclimation to UVA.