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The effect of heat shock on DNA integrity in leaves of Nicotiana tabacum L.

Plants are sessile organisms incapable to escape from the harmful environment. Therefore, plants have evolved a variety of responses to protect and preserve cellular homeostasis. Moreover, many different forms of abiotic stress, temperature as well, are known to disrupt metabolic balance inducing oxidative damage in the cells which respond by triggering the antioxidant defense, including peroxidases. Heat-induced DNA damage and DNA damage response are two interrelated mechanisms involved in maintaining integrity of the genome, but in plants are poorly understood. Therefore, to determine the possible genotoxic effect of short-term heat shock treatment at 42°C the alkaline comet assay has been applied to leaf cells of Nicotiana tabaccum 1- and 3-month old. Peroxidase activity was also evaluated as biomarker of temperature stress. Increased level of DNA damage and induction of peroxidase activity were noticed in response to heat shock treatment at 42°C. A new peroxidase isoform appeared only in 3-month old treated leaves. Following 24- hour recovery period, a further increase in DNA damage and tendency of DNA repair was observed in 1-month and 3-month old plants, respectively. Obtained results suggest genotoxic effect of high temperature but also that interplay between DNA damage and repair depends on the stage of leaf development.

Comet assay; heat shock; oxidative stress; Nicotiana tabacum

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