Magister Scientiae - MSc (Biotechnology)The mining industry in South Africa is of immense importance as this sector contributes
largely to the countries income. In the Limpopo province, a large production of antimony
(Sb) is generated per year. Antimony (Sb) is a trace element, which accumulates in the
environment through anthropogenic activities, such as mining and smelting industries.
Antimony is toxic to all living organisms and plants, and it is found to increase the
peroxidation of membrane lipids and encourage an antioxidant response. Sb contamination
in plants also accounts for DNA damage. The reduction in yield is due to the disruption of
plant metabolism by reactive oxygen species (ROS).
To combat abiotic stresses, plants have generated a signalling network that utilises multiple
growth regulators that would offer protection against the stress. An increase in ROS is one
of the responses to abiotic stresses. ROS is generated in response to the pants interaction
with heavy metals, through the Harber-Weiss reaction. ROS compounds include:
superoxide, hydrogen peroxide and hydroxyl radicals. Under normal conditions ROS
molecules are produced as by-products, however, under stressful conditions the production
of ROS molecules are increased to levels where they are detrimental to the plants.
Therefore, the accumulation of ROS results in damage to proteins, lipids, carbohydrates and
DNA which would lead to cellular death. ROS accumulation is thought to be a result of the
disruption in the balance of ROS production and the anti-oxidation systems. The antioxidative
system is thus introduced to restore the balance of ROS molecule production and
to combat oxidative damage caused by the ROS molecules. The anti-oxidative system
consists of various enzymes: superoxide dismutase, catalase, and ascorbate peroxidase and
glutathione reductase. Each antioxidant scavenges one or two ROS molecules
