Plant Responses to            UV            ‐            B            Radiation

<jats:title>Abstract</jats:title> <jats:sec> <jats:label/> <jats:p>Research on plant UV‐B responses commenced in earnest following discovery of stratospheric ozone layer depletion in the 1970s. Initial research focussed mostly on UV stress, including damage to genetic material (DNA, RNA) and negative impacts on photosynthesis and growth. A second phase of research centred on UV‐B acclimation including photorepair, UV‐screening and upregulation of antioxidant defences, and led to the conclusion that plants are well protected from potentially harmful effects of UV‐B radiation. The identification of a dedicated UV‐B photoreceptor (UVR8), and components of its signalling pathway, revealed that UV‐B sensing has an important regulatory role in UV‐protection. An emerging third phase of plant UV‐B biology centres on a much broader role of UV‐B radiation as an environmental regulator. UV‐B modulates, amongst others, thermomorphogenesis, shade‐avoidance, the circadian clock and resistance to drought. Thus, it appears that UV‐B plays a comprehensive role in controlling growth and development of plants.</jats:p> </jats:sec> <jats:sec> <jats:title>Key Concepts</jats:title> <jats:p> <jats:list list-type="bullet"> <jats:list-item> <jats:p>Realistic UV‐B exposure conditions are essential for assessing environmentally relevant UV‐B impacts.</jats:p> </jats:list-item> <jats:list-item> <jats:p>UV‐B is a potential stressor, however, negative impacts of UV‐B on the growth of plants are small under realistic UV‐B exposure conditions.</jats:p> </jats:list-item> <jats:list-item> <jats:p>The UV‐B photoreceptor UVR8 is used by plants to sense exposure to UV‐B radiation.</jats:p> </jats:list-item> <jats:list-item> <jats:p>Interactions between UVR8 and other photoreceptor signalling pathways result in fine‐regulation of plant responses.</jats:p> </jats:list-item> <jats:list-item> <jats:p>UVR8 plays a role in modulation of clock entrainment, chloroplast development, thermomorphogenesis, accumulation of specific metabolites, and drought‐protection.</jats:p> </jats:list-item> <jats:list-item> <jats:p> UV‐B modulates plant responses to climate change parameters such as heat, drought and CO <jats:sub>2</jats:sub> . </jats:p> </jats:list-item> </jats:list> </jats:p> </jats:sec>