CONICET | Buscador de Institutos y Recursos Humanos

Drought is a major environmental stress factor that affects the growth and developmentof plants. All plants have to maintain the reactive oxygen species withincertain levels for normal cellular homeostasis by means of their antioxidant systems,which can be classified as enzymatic and non-enzymatic. Plants underdrought stress generate an excess production of reactive oxygen species. At highconcentrations, this can be detrimental by producing damage to the proteinstructures and inhibiting enzymes, as well as oxidizing macromolecules, whichmay eventually lead to cell death. There has been increasing attention paid tothe antioxidant capacity of aromatic/medicinal plants, with a high antioxidantcontent having been reported in some plant extracts, such as in Mentha piperita(peppermint). Peppermint plants cultivated under drought stress also presenthigh levels of phenolic compounds, peroxidase enzyme activity and lipid peroxidationof membranes. A simple and inexpensive laboratory class is proposed forteaching some mechanisms that plants have evolved to avoid reactive oxygenspecies damage. The series of lab experiments described is aimed at demonstratingthe antioxidant status in aromatic plants subjected to drought stress, by measuringtotal phenolic compound content (non-enzymatic antioxidantcompound), peroxidase activity (enzymatic antioxidant) and malondialdehyde,as convenient biomarkers for lipid peroxidation. The proposed class will be carriedout by undergraduate students of the advanced biochemistry course, as partof our biology and agronomy studies. The experiment presented is intended tobe used as a vehicle to emphasize the concepts that students have learned intheir lectures. This lab exercise to be carried out by the students has dual goals:to apply a methodology only learned superficially on previous courses, and alsoto increase their understanding of how plants developed resistance mechanismsin order to tolerate drought stress.

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