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.

New Publications

Juan Vorster, Chris Cullis, Karl Kunert. (2019) Plant Vacuolar Processing Enzymes. Frontiers in Plant Science :00497. 10.3389/fpls.2019.00479 PDF
Cullis C, Lawler DW, Chimwamurombe P, Kunert K, Bbebe N, Vorster J. (2019) Development of marama bean, an orphan legume, as a crop. Food and Energy Security e00164:1-12. 10.1002/fes3.164 PDF
NM Okumu, BJ Vorster, CF Reinhardt. (2019) Growth-stage and temperature influence glyphosate resistance in Conyza bonariensis (L.) Cronquist.. South African Journal of Botany 121:248-256. 10.1016/j.sajb.2018.10.034 PDF
Cristopher Cullis, Percy Chimwamurombe, Nigel Barker, Karl Kunert, Juan Vorster. (2018) Orphan Legumes Growing in Dry Environments: Marama Bean as a Case Study. Frontiers in Plant Science 9:11999. 10.3389/fpls.2018.01199 PDF
Magdeleen Cilliers, Stefan van Wyk, Phillipus van Heerden, Karl Kunert, Juan Vorster. (2018) Identification and changes of the drought-induced cysteine protease transcriptome in soybean (Glycine max) root nodules. Journal of Experimental and Environmental Botany 148:59-69. 10.1016/j.envexpbot.2017.12.005