Dr Juan Vorster

Academic Staff
Molecular Plant Physiology

Research Interests

 

Cystatin / cysteine protease expression during development and stress in Soybean My main research is focus around plant cysteine protease inhibitors (Cystatins) and their interaction with cysteine proteases from both plants and insects or pathogens during development and stress. In this regard we are firstly trying to understand the timing of expression of different members of both the cystatin and cysteine protease gene families during normal development and senescence as well as under biotic and abiotic stress conditions in soybean. We also determine the inhibition potential of the various members of the cystatin gene family against both plant and insect cysteine proteases. In particular the project focuses on the role of cystatins and cysteine proteases in nodule development, senescence and stress resistance.
Co-evolution of functional variation in plant cystatins and insect proteases Plant cysteine protease inhibitors play an important role in plant defence through the inhibition of exogenous proteases of pathogens and the mid-gut proteases of herbivore insects.  It is known that herbivorous Coleoptera, especially  the Colorado potato beetle, compensate to dietary protease inhibitors in plant tissues through a multi-component defensive strategy involving the over-expression of inhibitor-sensitive digestive proteases, the expression of proteases insensitive to the inhibitors, and proteolytic inactivation of the inhibitory proteins using non-target proteases. More than 30 digestive cysteine proteases have been identified so far in the potato beetle, in line with the observed ability of this insect to elude the detrimental effects of cysteine protease inhibitors induced in wounded potato leaves. Our goal, in this study, is to determine whether functional diversity of the potato beetle digestive cysteine protease complement is matched with functional variability of the potato host cystatin complement, using the wound-inducible eight-domain cystatin, potato multicystatin (PMC), as a model. Computational modelling of the PMC domains interacting with Cys proteases of the beetle suggested the onset of variable interaction strengths for the PMC domains. We hope that a better understanding of the co-evolution and interactions amongst plant inhibitors and predator proteases will help in developing better strategies in crop protection.     Teaching I teach cources in Crop Protection and Crop Physiology in the Department of Plant Production and Soil Science.
Molecular Plant Physiology page

 

 

                     

Academic Qualifications

B.Sc. Plant Physiology(1999)

B.Sc (Hons) Genetics (2000)

M.Sc Molecular Biology (2003) Cum Laude

Ph.D Molecular Biology & Bioinformatics (2008)