Lancaster Environment Centre

I am a plant physiologist working in the area of Food Security and Sustainable Agriculture, to determine how plants cope with stresses such as drought and ozone pollution, and how we can apply this knowledge to water-saving agriculture and increased crop productivity. Plants often close stomatal pores on the leaf surfaces to retain precious water, and leaf growth is slowed, to reduce the surface area from which water can be lost.

These adaptations occur in response to plant-generated signals. At Lancaster, members of a team of scientists led by Distinguished Professor Bill Davies, within the Centre for Sustainable Agriculture, have worked hard to understand the signals that plants use, to send information from roots experiencing a reduction in the availability of water in the soil around them, and from leaves experiencing a stressful aerial environment.

Many of these signalling processes are now well understood, as a result of work carried out by the Davies group, and are currently being exploited in the field to reduce agricultural water consumption in many countries across the world. These signals often involve production, and changes in circulation, of the plant “drought hormone” abscisic acid (ABA), and/or production of the gaseous plant hormone ethylene. I have demonstrated that a change in the pH of plant sap is another of the signals that plants use, to alert their shoots that adaptive changes are required, in response to the sensation of stress either in the root or the shoot, or in response to changes in nitrate supply. Changes in sap pH alter the amounts of ABA that are transported between roots and shoots.

Another strand to my research is to understand how plants respond to multiple stresses. For example I have shown that a combination of ozone pollution and drought stress will be a particular problem for a crop in the field, as ozone prevents drought-induced ABA from closing stomata.

I have determined that the effect of ozone on droughted plants stems from an enhanced production of ethylene, which interferes with the ability of stomata to respond to ABA. We are currently screening more species to determine how widespread this effect is, and we are investigating ways to combat it in the field. This is being carried out using treatments designed to reduce ethylene production from the polluted plants (chemical treatments, rhizobacteria-based treatments).

In addition I am further investigating interactive effects of ABA and ethylene on stomata and growing leaves in unpolluted plants, as I believe that this will lead to new advances in water-saving agriculture.