Research
Overview
Work in Alistair Hetherington’s research group centres on investigating the fundamental mechanisms that allow plant cells to respond to a changing environment. More specifically the group is interested in identifying how plant cells couple the perception of extracellular stimuli to their characteristic intracellular responses. A significant part of the research in his group over the past 20 years has focussed on the role of calcium ions in this process and in particular identifying how plant cells generate the increases in intracellular calcium concentration that are key components in the process of signal transduction. To investigate intracellular signalling Alistair Hetherington’s research group works on stomatal guard cells. Guard cells control the aperture of the stomatal pores found on leaves and are important because they regulate CO2 uptake and H2O loss. Hence their correct function is vital to plant growth and survival.
Current Interests
Members of the research group work in two main areas and these are the control of stomatal development and the control of stomatal function by environmental signals.
The control of stomatal development (see Casson and Hetherington, 2009, in press).
A major interest is to understand how environmental variables such as atmospheric carbon dioxide, light and temperature control the number of stomata that form on the leaf surface. Previous work from the group, in association with Julie Gray’s lab in the University of Sheffield, resulted in the identification of the HIC gene that is involved in the signalling pathway by which carbon dioxide controls stomatal development (Gray et al 2000). We are also studying how light and temperature control stomata development. Recent work (Casson et al, 2009) showed that that red light and the phytochrome signalling system play a major role in the control of stomatal development by light. We use reverse and forward genetic approaches to identify mutants carrying lesions in signalling pathways responsible for the control of stomatal development by environmental signals.
The control of stomatal function (Hetherington and Woodward, 2003).
Stomata open and close in response to a range of environmental signals and work in the lab over a number of years has focussed on the responses to changes in carbon dioxide, relative humidity and the plant hormone abscisic acid (ABA). To gain insights into these processes the lab use forward and reverse genetic strategies combined with cell physiological approaches. Infrared thermal imaging has proved to be a very useful technique for the identification of mutants carrying lesions in stomatal function (Xie et al, 2006). An increase in the concentration of cytosolic free calcium is an important component in the signal transduction pathways responsible for coupling stimulus perception to changes in stomatal aperture (McAinsh et al 1990; Hetherington and Brownlee, 2004) and this has led to current projects on the role of sphingosine-1-phosphate (Ng et al 2001, Worral et al 2008) in guard cell signalling. As with projects on the role of stomatal development this area is being pursued using forward and reverse genetic strategies.
Overarching themes
As stomata are very important in controlling water use efficiency, and improving this character is important in the context of global climate change, the group is increasing activity in this area. This currently involves moving insights gained from work in Arabidopsis into wheat and barley. In addition, given that the acquisition of stomata is regarded as one of the key elements involved in the evolution of the vascular plants we are current investigating stomatal evolution.
Fig.1. Fig.2. Fig.3.
Fig.1 Thermal image of Arabidopsis humidity mutants Fig.2. S. moellendorfii stoma TS section through leaf cryo-fractured SEM image Fig.3. Light microscope image of a wheat stomata.