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Shrinking (Ultra-) Violet
By Scott Hayes - University of Bristol
It may be a surprising thought, but plants can see. They are able to distinguish light of different colours and they compute this information to form a picture of the world around them. My PhD has given me the opportunity to really delve into the world of plants, and to discover how they understand their environment.
Being sun loving and rooted to the ground, the ability to assess the quality and composition of light is incredibly important to plants. For instance, imagine a newly established seedling happily basking in full sunlight. If a neighbour starts to encroach upon this plant, the local light environment changes drastically. When it senses the looming threat of shade, our seedling initiates a series of developmental responses, driving the elongation of stems and leaves, in the hope that it can retain access to full sunlight.
Over the course of my PhD I have discovered that even low levels of ultraviolet-B radiation (UV-B, the component of sunlight that gives you a tan) are able to put a drastic brake on these ‘shade-avoidance’ elongation responses. Under UV-B, plants stop excessive elongation and adopt a more compact structure. What really excites me is uncovering how these signals interact on a molecular level. It’s a small piece of the puzzle, but it all adds up to give us a better picture of how plants see their surroundings and how they use this information to optimise growth.
Knowing how shade-avoidance is affected is of huge importance to agriculture. Excessive elongation not only effects the aesthetics of crops (gangly looking coriander anyone?), but also reduces yields, with plants putting all their energy into over-topping competitors, rather than fighting off pathogens and producing the grains, fruit and leaves we eat. Shade-avoidance is particularly detrimental in indoor grown crops, where space is a strong limiting factor. Unfortunately, UV-B is almost entirely filtered out by glass and polytunnels.
My research adds to the increasing realisation among plant scientists that UV-B is an important informational signal in sunlight. I hope that in the future, the incorporation of UV-B into industrial growth systems may allow for the more efficient production of indoor-grown crops.
Investigating the role of UV-B light in plant development
