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Keara Franklin

Dr Keara Franklin

Dr Keara Franklin

Research Fellow

Interests and expertise (Subject groups)

Grants awarded

Light and Temperature Signal Crosstalk in Plant Development

Scheme: University Research Fellowship

Organisation: University of Bristol

Dates: Oct 2011-Mar 2016

Value: £292,083.76

Summary: My research focuses on crosstalk between light and temperature signalling pathways in plant development. When growing in crowded communities, plants compete with neighbouring vegetation for light to fuel photosynthesis. Plants detect the presence of competitors through a reduction in the ratio of red to far-red wavelengths (low R:FR ratio) in light reflected from or transmitted through green tissues. Changes in light quality are perceived by specialised photoreceptors (phytochromes) and initiate a suite of elongation responses termed shade avoidance. The elongation of plant stems enables plants to overtop competitors but often occurs at the expense of leaf development and plant biomass, reducing yield. Similar elongation responses are observed at high temperature. These thermomorphogenic adaptations facilitate leaf cooling but also decrease yield. Understanding the molecular mechanisms through which plants respond to changes in both light quality and ambient temperature is of increasing importance with regard to understanding the effects of global climate change on crop productivity. Towards this aim, we have established that shade and high temperature signalling pathways converge on the transcription factor PIF4 which regulates biosynthesis of the growth hormone auxin. Current work focusses on the integration of UV-B with low R:FR and high temperature signalling. We have shown that UV-B perceived by the photoreceptor protein UVR8 suppresses shade avoidance by inhibiting auxin synthesis. UV-B-mediated suppression of stem elongation is also observed at high temperature, although the underlying molecular mechanisms differ from those in shade avoidance. Excessive stem elongation is a problem in commercial horticulture, where plants are grown densely, temperatures can rise steeply and UV-B is often absent. We are therefore working with industry, developing UV-B supplementation protocols to manipulate plant architecture in a commercial setting.

Ambient Temperature and Plant Development

Scheme: University Research Fellowship

Organisation: University of Bristol

Dates: Oct 2006-Sep 2011

Value: £405,484.26

Summary: Temperature and light are two of the most important environmental stimuli regulating plant development. Light signals are perceived using a family of photoreceptors named phytochromes. My current research is investigating crosstalk between ambient temperature and phytochrome signalling in plants. When growing in crowded communities, plants compete with neighboring vegetation for light to fuel photosynthesis. The presence of neighboring vegetation is detected as a reduction in the ratio of red to far red wavelengths (low R:FR ratio) in the light reflected from or transmitted through green tissues. This change in light quality is perceived by phytochrome and initiates a suite of elongation responses termed the shade avoidance syndrome, often at the expense of leaf development and plant biomass. These responses serve to elevate leaves towards gaps in the canopy and enable plants to overtop competitors. We have observed that plants display a very different shade avoidance strategy when grown at cooler temperatures and are now dissecting regulatory mechanisms involved. When plants are grown at high temperature, they display a suite of developmental responses similar to the standard shade avoidance syndrome, suggesting light and temperature sensing pathways may share signalling mechanisms. We have established that the phytochrome-interacting protein PHYTOCHROME INTERACTING FACTOR 4 is a master regulator of high temperature-mediated elongation growth in Arabidopsis and are now dissecting the molecular signalling pathway(s) involved. We are also investigating the effects of stem elongation on leaf cooling at high temperatures. This research programme addresses fundamental mechanisms of plant growth and is therefore of interest to all plant biologists. Understanding the molecular mechanisms through which plants respond to changes in ambient temperature is of increasing importance with regard to understanding the effects of global climate change on crop productivity

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