The broad aim of our research is to understand how light regulates plant growth and development. Plants detect several parameters of their light-environment (spectral quality, quantity, duration and direction of exposure) using a range of photoreceptors, and use the information to regulate numerous aspects of their morphogenesis, metabolism and physiology. These processes are crucial because they enable plants to optimise growth in their environment and they enhance crop production.

The specific focus of our research is to uncover the cellular and molecular mechanisms involved in regulation of plant processes by ultraviolet-B (UV-B) light. To do this we use a combination of experimental approaches: molecular genetics, protein biochemistry, cell biology, and photobiology, principally with the model plant Arabidopsis thaliana.

Why study plant responses to UV-B? UV-B radiation is only a small fraction of sunlight, but it is the most energetic part of the daylight spectrum and has the potential to damage molecules such as DNA and impair cellular processes. The potentially damaging effects of UV-B are well known because they cause sunburn and some forms of skin cancer in humans. Plants are unavoidably exposed to UV-B as they need to capture sunlight for photosynthesis, but they only rarely display signs of UV-damage in the natural environment because they have evolved very effective mechanisms for UV-protection and repair. The protective mechanisms include the deposition of UV-absorbing phenolic ‘sunscreen’ compounds in the outer tissues and repair of UV-damage involves enzymes such as DNA photolyases. These protective mechanisms are induced when plants are exposed to UV-B. Furthermore, responses to UV-B modify plant metabolism, physiology, morphology and development. UV-B exposure produces more compact plants and enhances tolerance to various stress conditions. In addition, UV-B alters the biochemical composition of plants, which helps to deter pests and pathogens and enhances the nutritional quality of various crops. All of these plant responses to UV-B are underpinned by extensive changes in gene expression: UV-B exposure modifies the expression of hundreds of genes, including those involved in metabolism and morphogenesis.

How do plants detect and respond to UV-B? Many plant responses to UV-B are initiated by the photoreceptor UVR8 (UV RESISTANCE LOCUS 8), the only photoreceptor that specifically detects UV-B and short wavelength UV-A light. UVR8 forms a homodimer in the absence of UV-B. UV-B photoreception causes dissociation of the dimer to generate active monomers, which initiate gene expression responses through physical interaction with a number of other proteins. Our research is focused on understanding how UVR8 mediates responses to UV-B. We are studying the structural basis of UVR8’s ability to function as a photoreceptor, how it interacts with other proteins to initiate changes in gene transcription, and how gene expression underpins the regulation of plant processes by UV-B.

For more information: Jenkins, G.I. (2017) Photomorphogenic responses to ultraviolet-B light. Plant Cell & Environment 40, 2544-57.