Resumo

NAVARRO BORRELL, Adriana; RODES, Rosa; ORTEGA-RODES, Patricia  e  ORTEGA, Eduardo. Temperature stress provoke necrosis in black tobacco; quantification by image analysis. Rev. colomb. biotecnol [online]. 2008, vol.10, n.2, pp.63-71. ISSN 0123-3475.

Black tobacco (Nicotiana tabacum L.) is an important cash crop in Cuba; it is used in the manufactory of Habano cigars. Biotic and abiotic factors affect it, so the studies of physiological damages caused by stress are valuable. The aim of this research was to quantify the effects of temperature stress causing necrotic damage in leaves and to determine the accumulation of hydrogen peroxide (H₂O₂) in situ on the tissues of Nicotiana tabacum L. (variety Havana-2000). Different treatments of temperature were applied (4 ºC, 25 ºC, 45 ºC and 60 ºC) in leaves of 4 weeks old plants; the necrosis was revealed with trypan blue solution. The area of peroxide accumulation (H₂O₂) in tissues of complete plants 7 days after germination, submitted to the same stress conditions, was determined with DAB. The percentage of necrotic area and of accumulation of H₂O₂ was measured using the ImageJ software. It can acquire, display, edit, enhance, and analyze images. It was demonstrated that leaves treated to temperature of 4 ºC, independently of the time of exhibition, presented a bigger necrotic area (35%) in comparison with the rest of the treatments. The areas with H₂O₂ accumulation in situ were higher in the stress treatments with higher temperatures (45 ºC and 60 ºC). The detection and quantification of the necrosis produced by extreme temperatures combining the trypan blue method with the analysis of images is a useful tool to evaluate damages produced by temperature stress and it could be used to evaluate cell damages provoked by other types of stress.

Palavras-chave : Habana-2000-variety; reactive oxygen species; H₂O₂.

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