Guard cell wall epitope patterns and stomatal function

Water use efficiency is an important determinant of crop yield, particularly in drought prone countries. Water is lost from plants through the stomata, microscopic pores in the epidermal surface of the leaf, which are flanked by two specialised guard cells. The guard cells expand to open the stomatal pore through which gases enter and leave the plant, and consequently water is also lost. The guard cells must be highly flexible yet strong to allow for stomatal opening and closure. These structural properties are thought to be due to the specialised guard cell wall, which is known to be enriched in polysaccharides which confer strength and flexibility. In this project I am aiming to use molecular and imaging techniques to identify the structural and mechanical properties of the Arabidopsis guard cell walls and the genes responsible for these phenotypes. This will allow for the creation of mutant lines which are deficient in these identified genes, which can then be tested for whole plant physiological traits such as gas exchange.

Previous work on guard cell wall mechanics has all been carried out in Arabidopsis, so the next stage of the project is to collate this data and investigate guard cell walls in a crop species. Immunolabelling techniques will help to determine whether Arabidopsis and grass guard cells show similar structural properties and functional analysis will show whether grass guard cell walls display genes homologous to Arabidopsis guard cell wall genes. Mutant lines can be created to investigate the effects of selected genes upon the guard cells and subsequent whole plant physiological traits.

Overall this project aims to transfer our current knowledge of guard cell walls into a crop species. Previous work has shown that the manipulation of guard cell wall genes in Arabidopsis can alter the movement of the guard cells, and this may also be true of grasses. In the future this may have the potential to improve plant growth under the predicted climatic conditions of elevated CO2 and reduced water availability.