Molecular Plant Physiology
Research Areas
Plant Cystatins
Several sub-projects in this field aim to increase our understanding of the inhibition and regulation of cysteine protease activity by plant cystatins. This includes the role of cysteine proteases and cystatins during nodule development and senescence in soybean as well as the possibility of using cystatins to increase abiotic stress resistance in nodules. A further project relates to the inhibition of insect digestive proteases by plant cystatins and their potential for use in developing insect resistant crops. We study the function and importance of specific amino acids in the cystatin proteins using techniques such as homology modelling and protein-protein docking to study and predict specific interactions in silico. We also change specific amino acids in the proteins through site-directed mutagenesis in order to study their effect on the inhibition potential of the modified cystatins in vitro. Selected cystatins have also been recombinantly expressed in various plants to evaluate their role in vivo particularly in repressing senescence and protein degradation.
Nodule Improvement
The overall aim of this project is to develop a joint training and cutting edge research program based on "state of the-art", technologies that will strengthen the research partnership between the University of Pretoria in South Africa, the Leeds University, UK and VIB Ghent, Belgium in legume improvement, which is of major agronomic importance both in the EU and in Africa. This aim will be achieved through short and longer-term periods of staff exchanges between the African and European partners and networking activities between the three institutions. The ultimate goal of this project is to achieve more rapid progress in advancing current knowledge and concepts through joint endeavour leading to joint-author high citation index publications and possibly also patents. In this way we will establish a long-term research cooperation between the three institutions based on active technology and scientific knowledge application and transfer. In general, nodule development is a complex process that has been insensitively studied for many years. However, key questions remain concerning the orchestration of bacterial infection, nodule development and nodule senescence in relation to the senescence of the whole plant. As with other major crops, grain legume production can be severely restricted by environmental stresses. However, little information is available on the mechanisms that cause the breakdown of symbiosis particularly during stress. The mechanisms that trigger the end of symbiosis in development-dependent and stress-induced nodule senescence remain to be characterised. This project is focused on nodule development from the point where the bacteria are taken up by the plant cells, develop into bacteroids within symbiosomes and start to fix atmospheric nitrogen to the point where symbiosis ends and the nodules loose the ability to fix atmospheric nitrogen. Although the initial steps of nodule development, mediated by the bacterial Nod factors have been intensively studied, relatively few traits that have the potential to contribute or enhance nitrogen fixation in agricultural practices have been characterised in terms of molecular and protein biology. This project will address this issue directly and contribute to current knowledge and concepts of nodule development and sustainability. The proposed joint research effort is based on the interfacing and interdisciplinary skills and knowhow of each of the partners.