Assessment of the ozone tolerance of two soybean cultivars (Glycine max cv. Sambaíba and Tracajá) cultivated in Amazonian areas.
Brazilian soybean cultivars (Glycine max Sambaíba and Tracajá) routinely grown in Amazonian areas were exposed to filtered air (FA) and filtered air enriched with ozone (40 and 80 ppb, 6 h/day for 5 days) to assess their level of tolerance to this pollutant by measuring changes in key biochemical, physiological, and morphological indicators of injury and in enzymatic and non-enzymatic antioxidants. Sambaíba plants were more sensitive to ozone than Tracajá plants, as revealed by comparing indicator injury responses and antioxidant stimulations. Sambaíba exhibited higher visible leaf injury, higher stomatal conductance, and a severe decrease in the carbon assimilation rate. Higher ozone level (80 ppb) caused an increase in cell death in both cultivars. Levels of malondialdehyde and hydrogen peroxide also increased in Tracajá exposed under 80 ppb. Sambaíba plants exhibited decreases in ascorbate and glutathione levels and in enzymatic activities associated with these antioxidants. The higher tolerance of the Tracajá soybean appeared to be indicated by reduced physiological injuries and lower stomatal conductance, which might decrease the influx of ozone and enhance oxidation-reduction reactions involving catalase, ascorbate peroxidase, ascorbate, and glutathione, most likely stimulated by higher hydrogen peroxide.
Núcleo de Pesquisa em Ecologia, Instituto de Botânica, São Paulo, SP, CEP 04045-972, Brazil, pbulbovas@hotmail.com.
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Bulbovas
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Souza
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Esposito
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Moraes
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Alves
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Domingos
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Azevedo
D000383:Agriculture / Q000379:methods*; D000393:Air Pollutants / Q000009:adverse effects*; D000704:Analysis of Variance; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D001938:Brazil; D016923:Cell Death / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D010084:Oxidation-Reduction; D010126:Ozone / Q000009:adverse effects*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D054046:Plant Stomata / Q000187:drug effects; D013025:Glycine max / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D013045:Species Specificity; D013482:Superoxide Dismutase / Q000378:metabolism
D000393:Air Pollutants; D000975:Antioxidants; D010126:Ozone; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D001205:Ascorbic Acid