WRI Visiting Scientist Seminar – Professor Tracy Lawson

Abstract

In order for leaf photosynthesis to take place CO₂ must enter the leaf through adjustable pores, called stomata, and at the same time water is lost through these pores which also aids in cooling of the leaf. Stomata open in response to increasing light, however this response depends on the wavelength of light, and two responses have been identified. The first named the “red” light or mesophyll response, occurs at high light levels and is linked directly to the rate of photosynthesis. The second is the “specific blue” light response, which occurs and is saturated at light levels too low to drive photosynthesis. This means that stomata are often more open than they need to be to achieve maximum CO₂ uptake for photosynthesis, and therefore the ratio of carbon gain to water loss known as Water Use Efficiency (WUE) is reduced.  Here we examine stomatal sensitivity to blue light in a number of species and explore the potential to manipulate this process to optimise crop resource use. A second strategy we are exploring is the speed of stomatal responses to changes in light intensity. As stomatal responses tend to be an order of magnitude greater than photosynthetic responses this can lead to periods of reduced assimilation when stomatal opening is slow as well as periods of unnecessary water loss by slow stomatal closure when the photosynthetic rate has dropped. Both of these approaches have the potential to increase crop photosynthesis and WUE, which are critical for yield. 

About the speaker

Professor Tracy Lawson is a professor in the Plant Productivity group and Director of Plant Phenotyping at Essex, with over 25 years’ experience in photosynthesis research. She obtained her first degree in Applied Biology in 1993 from Liverpool and PhD from Dundee in 1997.  Her research focuses on the stomatal control of atmospheric gas entry into the leaf, associated water loss and the mechanisms that regulate this process. Recent research has paid particular attention to stomatal kinetics and the impact of dynamic environments on both photosynthesis and stomatal behaviour. Tracy’s work also concentrates on phenotyping including chlorophyll fluorescence techniques (for quantifying light use and photosynthetic efficiency) and thermal imaging (for measuring stomatal responses and kinetics). Lawson’s lab developed the first imaging system for screening plant water-use-efficiency (McAusland et al., 2013).

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