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

Mbedzi PP, Van den Hooven L, Vorster BJ , Van der Waals J. (2019) Screening for Sclerotinia sclerotiorum resistance using detached leaf assays and simple sequence repeat markers in soybean cultivars. Crop Protection 215:104909. 10.1016/j.cropro.2019.104909 PDF
Kibido T, Kunert K, Makgopa M, Greve M, Vorster BJ . (2019) Improvement of rhizobium‐soybean symbiosis and nitrogen fixation under drought. Food and Energy Security :e117. 10.1002/fes3.177 PDF
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