Why are plants sensing UV-B radiation using a dedicated UV-B photoreceptor? This is an intriguing question, especially as UV-B induced stress is rare in well adapted plants. A novel paper by Rippa et al. reports that UV-B drives a cooling response in plant leaves, implying that plants “exploit” UV-B to adjust to warm, sunny weather.

Rippa, M. et al. (2020) Active thermography for real time monitoring of UV-B plant interactions. Journal of Photochemistry and Photobiology B: Biology, 208, 111900. https://www.sciencedirect.com/science/article/abs/pii/S101113442030350X

The UV-mediated induction of plant metabolites has important consequences for the plant, but also for other organisms that feed on plant tissues. This paper by Takshak and Agrawal highlights the importance of UV induced metabolites in medicinal plants and details how these metabolites can benefit consumer species.

Takshak, S. and Agrawal, S.B. (2019) Defense potential of secondary metabolites in medicinal plants under UV-B stress. Journal of Photochemistry and Photobiology B: Biology, 193, 51-88. https://doi.org/10.1016/j.jphotobiol.2019.02.002

The UV-mediated inhibition of plant elongation responses results in a more compact, dwarfed organism. Such “dwarfing” has consequences when plants are competing for exposure to photosynthetic light, with smaller plants more likely to be shaded. However, compact plants are also a major advantage for the horticultural trade. Plants are shipped all over the world and a more compact organism can save considerably on transport costs. This paper by Tavridou et al. identifies parts of the mechanism underlying the dwarfing response.

Tavridou, E., Pireyre, M. and Ulm, R. (2020) Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis. The Plant Journal, 101(3), 507-517. https://doi.org/10.1111/tpj.14556

The commercial exploitation of UV for plant production continues to drive the need to improve plant UV research. This commercial exploitation is in part due to the development of novel LEDs that can provide specific UV wavelengths – which make it possible to manipulate the impact of UV on plants. However, plant UV research still needs to be further developed to become commercially viable. This paper by Robson et al. (2019) highlights potential knowledge gaps that need to be addressed in order to improve exploitation of plant UV research further.

Robson, T.M., Aphalo, P.J., Banaś, A.K., et al. (2019) A perspective on ecologically relevant plant-UV research and its practical application. Photochem Photobiol Sci 18, 970–988. https://doi.org/10.1039/C8PP00526E

Ireland is not a country known for its sunshine and exposure to UV-radiation. However, a new paper by Dr Aoife Coffey and Prof. Marcel Jansen shows that natural, solar UV-B radiation has measurable effects on plants grown outdoors in Ireland. In the Irish summer, plants exposed to UV-containing sunlight stay considerably more compact compared to those exposed to filtered sunlight, devoid of UV radiation.

Coffey, A. and Jansen, M.A.K. (2019) Effects of natural solar UV-B radiation on three Arabidopsis accessions are strongly affected by seasonal weather conditions. Plant Physiol Biochem. 134: 64-72. https://doi.org/10.1016/j.jphotobiol.2019.02.002

The UNEP Environmental Effects Assessment Panel (EEAP) has been reporting on the various effects of ozone layer depletion since 1989. Annual reports capture recent research highlights, while quadrennial reports summarise the larger, important trends in our understanding of the impacts of ozone layer depletion. The latest (annual) report was published in 2020, and the part on impacts of UV on terrestrial ecosystems can be found in:

Bernhard GH, Neale RE, Barnes PW, et al. (2020) Environmental effects of stratospheric ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2019. Photochem. Photobiol. Sci., 2020, 19, 542-584. https://doi.org/10.1039/D0PP90011G

Improvements in LED technology open new opportunities for horticultural lighting. This article by Kusuma et al. discusses the fundamental physics and efficiency of LEDs for plant growth. Spectral quality of lighting affects photosynthesis and plant shape, and is discussed in the context of use of light fixtures in horticulture.

Kusuma, P., Pattison, P.M. and Bugbee, B. (2020) From physics to fixtures to food: current and potential LED efficacy. Hortic Res 7, 56-64. https://doi.org/10.1038/s41438-020-0283-7